diff --git a/config/install/sms.gateway.config.yml b/config/install/sms.gateway.config.yml
new file mode 100644
index 0000000..aa353e0
--- /dev/null
+++ b/config/install/sms.gateway.config.yml
@@ -0,0 +1,3 @@
+log:
+  enabled: true
+  plugin_id: log
diff --git a/config/schema/sms.schema.yml b/config/schema/sms.schema.yml
index d8ddd63..28d51f5 100644
--- a/config/schema/sms.schema.yml
+++ b/config/schema/sms.schema.yml
@@ -20,11 +20,30 @@ sms.settings:
         - type: string
 
 # Configuration for sms gateways.
-sms.gateway.*:
+sms.gateway.config:
+  type: sequence
+  label: 'All SMS Gateway configuration'
+  sequence:
+    - type: sms.gateway.setting
+
+sms.gateway.setting:
   type: mapping
-  label: 'SMS Gateway settings'
+  label: 'Single SMS Gateway configuration'
   mapping:
-    settings:
+    label:
+      type: label
+      label: 'Human readable gateway label'
+    name:
+      type: string
+      label: 'Gateway machine name'
+    plugin_id:
+      type: string
+      label: 'Gateway plugin type'
+    enabled:
+      type: boolean
+      label: 'Gateway enabled status'
+    custom:
       type: sequence
+      label: 'Additional gateway-specific configuration'
       sequence:
         - type: string
diff --git a/sms.links.action.yml b/sms.links.action.yml
index eec7b10..f4f6527 100644
--- a/sms.links.action.yml
+++ b/sms.links.action.yml
@@ -4,3 +4,10 @@ sms.carrier_add:
   weight: 1
   appears_on:
     - sms.carrier_admin
+
+sms.gateway_add:
+  title: 'Add Configurable Gateway'
+  route_name: sms.gateway_add
+  weight: 1
+  appears_on:
+    - sms.gateway_admin
diff --git a/sms.module b/sms.module
index edbd314..4db981b 100644
--- a/sms.module
+++ b/sms.module
@@ -20,7 +20,7 @@ define('SMS_CARRIER_OVERRIDDEN', 1);
 define('SMS_CARRIER_NORMAL', 3);
 
 use Drupal\sms\Gateway\GatewayInterface;
-use Drupal\sms\Message\Message;
+use Drupal\sms\Message\SmsMessage;
 
 /**
  * Implements hook_theme().
@@ -60,8 +60,8 @@ function sms_cron_queue_info() {
  * @see sms_handle_result().
  */
 function sms_send($number, $message, $options = array()) {
-  $sms = new Message($options['sender'], explode(',', $number), $message, $options);
-  return \Drupal::service('sms.provider')->send($sms, $options);
+  $sms = new SmsMessage($options['sender'], explode(',', $number), $message, $options);
+  return \Drupal::service('sms_provider.default')->send($sms, $options);
 }
 
 /**
@@ -93,44 +93,17 @@ function sms_incoming_queue_worker(array $item) {
  *   An array of additional options.
  */
 function sms_incoming($number, $message, $options = array()) {
-  if (\Drupal::moduleHandler()->moduleExists('rules')) {
-    $options += array('number' => $number, 'message' => $message);
-    rules_invoke_event('sms_incoming', $options);
-  }
-
-  // Execute three phases
-  \Drupal::moduleHandler()->invokeAll('sms_incoming', ['pre process', $number, $message, $options]);
-  \Drupal::moduleHandler()->invokeAll('sms_incoming', ['process', $number, $message, $options]);
-  \Drupal::moduleHandler()->invokeAll('sms_incoming', ['post process', $number, $message, $options]);
+  $sms = new SmsMessage($options['sender'], explode(',', $number), $message, $options);
+  \Drupal::service('sms_provider.default')->incoming($sms, $options);
 }
 
 /**
  * Handles responses to message transactions.
  *
- * Allows gateways modules to pass message receipts and other responses to
- * messages in a standard format for processing, and provides a basic set of
- * status codes for common code handling.
- *
- * Allowed message status codes are defined as constants in this module.
- *
- * The gateway status code and message should be provided in the $options array
- * as 'gateway_message_status' and 'gateway_message_status_text'.
- *
- * @param string $number
- *   The sender's mobile number.
- * @param string $reference
- *   Unique message reference code, as provided when message is sent.
- * @param int $message_status
- *   (optional) An SMS Framework message status code, per the defined constants.
- *    Defaults to SMS_GW_UNKNOWN_STATUS.
- * @param array $options
- *   (optional) Extended options passed by the receipt receiver.
+ * @see \Drupal\sms\Gateway\SmsProviderInterface::receipt
  */
 function sms_receipt($number, $reference, $message_status = GatewayInterface::STATUS_UNKNOWN, $options = array()) {
-  // Execute three phases
-  \Drupal::moduleHandler()->invokeAll('sms_receipt', 'pre process', $number, $reference, $message_status, $options);
-  \Drupal::moduleHandler()->invokeAll('sms_receipt', 'process', $number, $reference, $message_status, $options);
-  \Drupal::moduleHandler()->invokeAll('sms_receipt', 'post process', $number, $reference, $message_status, $options);
+  \Drupal::service('sms_provider.default')->incoming($number, $reference, $message_status, $options);
 }
 
 /**
@@ -139,7 +112,7 @@ function sms_receipt($number, $reference, $message_status = GatewayInterface::ST
  * @return \Drupal\sms\Gateway\GatewayInterface
  */
 function sms_default_gateway() {
-  return \Drupal::service('plugin.manager.smsgateway')->getDefaultGateway();
+  return \Drupal::service('plugin.manager.sms_gateway')->getDefaultGateway();
 }
 
 /**
@@ -168,15 +141,15 @@ function sms_default_gateway_id() {
  *
  * @deprecated as of 8.x-1.x. Use @code GatewayManager @endcode methods instead.
  * @code
- *   Drupal::service('plugin.manager.smsgateway')->getAvailableGateways();
- *   Drupal::service('plugin.manager.smsgateway')->getEnabledGateways();
- *   Drupal::service('plugin.manager.smsgateway')->getDefaultGateway();
- *   Drupal::service('plugin.manager.smsgateway')->getGateway($name);
+ *   Drupal::service('plugin.manager.sms_gateway')->getAvailableGateways();
+ *   Drupal::service('plugin.manager.sms_gateway')->getEnabledGateways();
+ *   Drupal::service('plugin.manager.sms_gateway')->getDefaultGateway();
+ *   Drupal::service('plugin.manager.sms_gateway')->getGateway($name);
  * @endcode
  */
 function sms_gateways($op = 'gateways', $gateway = NULL) {
   /** @var \Drupal\sms\Gateway\GatewayManagerInterface $gateway_manager */
-  $gateway_manager = \Drupal::service('plugin.manager.smsgateway');
+  $gateway_manager = \Drupal::service('plugin.manager.sms_gateway');
 
   switch ($op) {
     case 'gateway':
@@ -486,10 +459,8 @@ function sms_validate_number(&$number, $options = array()) {
   else {
     $gateway = sms_default_gateway();
   }
-  if (isset($gateway['validate number']) && function_exists($gateway['validate number'])) {
-    if ($error = $gateway['validate number']($number, $options)) {
-      $errors += (array) $error;
-    }
+  if ($error = $gateway->validateNumbers([$number], $options)) {
+    $errors += (array) $error;
   }
 
   return $errors;
diff --git a/sms.routing.yml b/sms.routing.yml
index bd2ef6c..099d5ff 100644
--- a/sms.routing.yml
+++ b/sms.routing.yml
@@ -14,6 +14,14 @@ sms.gateway_admin:
   requirements:
     _permission: 'administer smsframework'
 
+sms.gateway_add:
+  path: '/admin/config/smsframework/gateways/add'
+  defaults:
+    _form: '\Drupal\sms\Form\GatewayAddForm'
+    _title: 'Add new gateway configuration'
+  requirements:
+    _permission: 'administer smsframework'
+
 sms.gateway_config:
   path: '/admin/config/smsframework/gateways/{gateway_id}'
   defaults:
@@ -62,3 +70,10 @@ sms.bootstrap_admin:
     _title: 'Incoming SMS bootstrap'
   requirements:
     _permission: 'administer smsframework'
+
+sms.delivery_report:
+  path: '/sms/deliveryreport/{gateway_id}'
+  defaults:
+    _controller: '\Drupal\sms\DeliveryReportController::acknowledgeDelivery'
+  requirements:
+    _access: 'TRUE'
diff --git a/sms.services.yml b/sms.services.yml
index c5e4aa5..39f9257 100644
--- a/sms.services.yml
+++ b/sms.services.yml
@@ -1,8 +1,8 @@
 services:
-  sms.provider:
-    class: Drupal\sms\Sms
-    arguments: ['@plugin.manager.smsgateway', '@module_handler']
+  sms_provider.default:
+    class: Drupal\sms\Provider\DefaultSmsProvider
+    arguments: ['@plugin.manager.sms_gateway', '@module_handler']
 
-  plugin.manager.smsgateway:
+  plugin.manager.sms_gateway:
     class: Drupal\sms\Gateway\GatewayManager
-    arguments: ['@container.namespaces', '@config.factory', '@module_handler']
+    arguments: ['@container.namespaces', '@config.factory', '@cache.discovery', '@module_handler']
diff --git a/src/Annotation/SmsGateway.php b/src/Annotation/SmsGateway.php
index 1cf32b0..a2293f7 100644
--- a/src/Annotation/SmsGateway.php
+++ b/src/Annotation/SmsGateway.php
@@ -1,4 +1,5 @@
 <?php
+
 /**
  * @file
  * Contains \Drupal\sms\Annotation\SmsGateway
@@ -14,6 +15,7 @@ use Drupal\Component\Annotation\Plugin;
  * @Annotation
  */
 class SmsGateway extends Plugin {
+
   /**
    * The machine name of the sms gateway.
    *
@@ -33,4 +35,5 @@ class SmsGateway extends Plugin {
    * @var bool
    */
   protected $configurable;
+
 }
diff --git a/src/DeliveryReportController.php b/src/DeliveryReportController.php
new file mode 100644
index 0000000..0420c3c
--- /dev/null
+++ b/src/DeliveryReportController.php
@@ -0,0 +1,71 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\sms\DeliveryReportController
+ */
+
+namespace Drupal\sms;
+
+use Drupal\Core\DependencyInjection\ContainerInjectionInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Drupal\sms\Gateway\GatewayManagerInterface;
+use Symfony\Component\HttpFoundation\RequestStack;
+use Symfony\Component\HttpFoundation\Response;
+
+/**
+ * Provides delivery reports acknowledgement and passes to the correct gateway.
+ */
+class DeliveryReportController implements ContainerInjectionInterface {
+
+  /**
+   * The gateway manager.
+   *
+   * @var \Drupal\sms\Gateway\GatewayManagerInterface
+   */
+  protected $gatewayManager;
+
+  /**
+   * The request stack.
+   *
+   * @var \Symfony\Component\HttpFoundation\RequestStack
+   */
+  protected $requestStack;
+
+  /**
+   * Creates an new delivery report controller.
+   *
+   * @param \Drupal\sms\Gateway\GatewayManagerInterface $gateway_manager
+   *   The gateway manager.
+   * @param \Symfony\Component\HttpFoundation\RequestStack $request_stack
+   *   The request stack.
+   */
+  public function __construct(GatewayManagerInterface $gateway_manager, RequestStack $request_stack) {
+    $this->gatewayManager = $gateway_manager;
+    $this->requestStack = $request_stack;
+  }
+
+  /**
+   * Acknowledges delivery reports and passes them to the correct gateway.
+   *
+   * @param string $gateway_id
+   *   The gateway id of the gateway that is to handle the delivery report.
+   *
+   * @return \Symfony\Component\HttpFoundation\Response
+   */
+  public function acknowledgeDelivery($gateway_id) {
+    $acknowledgement = $this->gatewayManager->getGateway($gateway_id)->deliveryReport($this->requestStack->getCurrentRequest());
+    return new Response($acknowledgement);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('plugin.manager.sms_gateway'),
+      $container->get('request_stack')
+    );
+  }
+
+}
diff --git a/src/Form/GatewayAddForm.php b/src/Form/GatewayAddForm.php
new file mode 100644
index 0000000..850483b
--- /dev/null
+++ b/src/Form/GatewayAddForm.php
@@ -0,0 +1,106 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\sms\Form\GatewayCreateForm
+ */
+
+namespace Drupal\sms\Form;
+
+use Drupal\Core\Config\ConfigFactoryInterface;
+use Drupal\Core\Form\FormBase;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\sms\Gateway\GatewayManagerInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+class GatewayAddForm extends FormBase {
+
+  /**
+   * The gateway manager.
+   *
+   * @var \Drupal\sms\Gateway\GatewayManagerInterface
+   */
+  protected $gatewayManager;
+
+  /**
+   * Constructor.
+   *
+   * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
+   *   The configuration factory.
+   * @param \Drupal\sms\Gateway\GatewayManagerInterface $gateway_manager
+   *   The gateway manager
+   */
+  public function __construct(ConfigFactoryInterface $config_factory, GatewayManagerInterface $gateway_manager) {
+    $this->setConfigFactory($config_factory);
+    $this->gatewayManager = $gateway_manager;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('config.factory'),
+      $container->get('plugin.manager.sms_gateway')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'gateway_create_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    $form['label'] = [
+      '#type' => 'textfield',
+      '#title' => $this->t('Gateway name'),
+    ];
+    $form['name'] = [
+      '#type' => 'machine_name',
+      '#title' => '',
+      '#machine_name' => [
+        'exists' => [$this, 'gatewayExists'],
+        'source' => ['label'],
+      ],
+    ];
+    $form['plugin_id'] = [
+      '#type' => 'select',
+      '#title' => $this->t('Gateway type'),
+      // List plugins that are configurable so user can choose.
+      '#options' => array_filter(array_map(function ($definition) {
+        return $definition['configurable'] ? $definition['label'] : FALSE;
+      }, $this->gatewayManager->getGatewayPlugins())),
+      '#required' => TRUE,
+    ];
+
+    $form['submit'] = [
+      '#type' => 'submit',
+      '#value' => $this->t('Create'),
+    ];
+
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+    // Create the gateway and redirect to the configure form.
+    $configuration = $form_state->cleanValues()->getValues();
+    $this->gatewayManager->addGateway($configuration['plugin_id'], $configuration);
+    $form_state->setRedirect('sms.gateway_config', ['gateway_id' => $configuration['name']]);
+  }
+
+  /**
+   * Helper function for machine_name form element.
+   */
+  public function gatewayExists($machine_name) {
+    return (bool) $this->gatewayManager->getGateway($machine_name);
+  }
+
+}
diff --git a/src/Form/GatewayConfigForm.php b/src/Form/GatewayConfigForm.php
index 3b74719..ff97ddb 100644
--- a/src/Form/GatewayConfigForm.php
+++ b/src/Form/GatewayConfigForm.php
@@ -2,13 +2,16 @@
 
 /**
  * @file
- * Contains GatewayConfigForm class
+ * Contains \Drupal\sms\Form\GatewayConfigForm
  */
 
 namespace Drupal\sms\Form;
 
+use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\Form\ConfigFormBase;
 use Drupal\Core\Form\FormStateInterface;
+use Drupal\sms\Gateway\GatewayManagerInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
 
 /**
@@ -18,6 +21,29 @@ use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
  * form more streamlined
  */
 class GatewayConfigForm extends ConfigFormBase {
+
+  /**
+   * The gateway manager.
+   *
+   * @var \Drupal\sms\Gateway\GatewayManagerInterface
+   */
+  protected $gatewayManager;
+
+  public function __construct(ConfigFactoryInterface $config_factory, GatewayManagerInterface $gateway_manager) {
+    $this->setConfigFactory($config_factory);
+    $this->gatewayManager = $gateway_manager;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('config.factory'),
+      $container->get('plugin.manager.sms_gateway')
+    );
+  }
+
   /**
    * {@inheritdoc}
    */
@@ -29,18 +55,27 @@ class GatewayConfigForm extends ConfigFormBase {
    * {@inheritdoc}
    */
   public function buildForm(array $form, FormStateInterface $form_state, $gateway_id = NULL) {
-    $gateway = sms_gateways('gateway', $gateway_id);
-    if ($gateway && !empty($gateway['configure form']) && function_exists($gateway['configure form'])) {
-      $form = $gateway['configure form']($gateway['configuration']);
-      $form['#title'] = $this->t('@gateway configuration', array('@gateway' => $gateway['name']));
-
+    $gateway = $this->gatewayManager->getGateway($gateway_id);
+    if ($gateway && $gateway->isConfigurable()) {
+      $form['title'] = [
+        '#type' => 'item',
+        '#title' => $gateway->getLabel(),
+        '#markup' => '(' . $gateway->getName() . ')',
+      ];
+      $form['enabled'] = [
+        '#type' => 'checkbox',
+        '#title' => $this->t('Enable this gateway'),
+        '#default_value' => $gateway->isEnabled(),
+      ];
+      $form = $gateway->buildConfigurationForm($form, $form_state);
+      $form['#title'] = $this->t('@gateway configuration', array('@gateway' => $gateway->getLabel()));
       $form['submit'] = array(
         '#type' => 'submit',
-        '#value' => $this->t('Save'),
+        '#value' => $this->t('Save configuration'),
       );
-      $form['gateway'] = array(
+      $form['gateway_id'] = array(
         '#type' => 'value',
-        '#value' => $gateway,
+        '#value' => $gateway->getIdentifier(),
       );
   
       return $form;
@@ -55,24 +90,24 @@ class GatewayConfigForm extends ConfigFormBase {
    */
   public function validateForm(array &$form, FormStateInterface $form_state) {
     // Pass validation to gateway.
-    $function = $form_state->getValue(['gateway', 'configure form']) . '_validate';
-    if (function_exists($function)) {
-      $function($form, $form_state);
-    }
+    $gateway = $this->gatewayManager->getGateway($form_state->getValue('gateway_id'));
+    $gateway->validateConfigurationForm($form, $form_state);
   }
 
   /**
    * {@inheritdoc}
    */
   public function submitForm(array &$form, FormStateInterface $form_state) {
-    $gateway = $form_state->getValue('gateway');
-    // Remove unnecessary values.
-    $form_state->cleanValues();
-    $form_state->unsetValue('gateway');
-
-    $this->configFactory()->getEditable('sms.gateway.' . $gateway['identifier'])
-      ->set('settings' , $form_state->getValues())
-      ->save();
+    // Call the gateway submission callback before saving configuration.
+    $gateway = $this->gatewayManager->getGateway($form_state->getValue('gateway_id'));
+    $gateway->setEnabled($form_state->getValue('enabled'));
+    $form_state
+      ->unsetValue('title')
+      ->unsetValue('enabled')
+      ->unsetValue('gateway_id')
+      ->cleanValues();
+    $gateway->submitConfigurationForm($form, $form_state);
+    $this->gatewayManager->saveGateway($gateway);
     drupal_set_message($this->t('The gateway settings have been saved.'));
     $form_state->setRedirect('sms.gateway_admin');
   }
@@ -81,8 +116,7 @@ class GatewayConfigForm extends ConfigFormBase {
    * Title callback fo the menu
    */
   public function getTitle($gateway_id) {
-    $gateway = sms_gateways('gateway', $gateway_id);
-    return sprintf('%s gateway', $gateway['name']);
+    return $this->t('@name gateway', ['@name' => $this->gatewayManager->getGateway($gateway_id)->getLabel()]);
   }
 
   /**
diff --git a/src/Form/GatewayDefaultForm.php b/src/Form/GatewayDefaultForm.php
index 3856657..1f08232 100644
--- a/src/Form/GatewayDefaultForm.php
+++ b/src/Form/GatewayDefaultForm.php
@@ -2,20 +2,49 @@
 
 /**
  * @file
- * Contains GatewayDefaultForm class
+ * Contains \Drupal\sms\Form\GatewayDefaultForm
  */
 
 namespace Drupal\sms\Form;
 
 use Drupal\Component\Utility\SafeMarkup;
+use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\Form\ConfigFormBase;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Url;
+use Drupal\sms\Gateway\GatewayManagerInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
  * Provides a configuration form for setting the default gateway.
  */
 class GatewayDefaultForm extends ConfigFormBase {
+
+  /**
+   * The gateway manager.
+   *
+   * @var \Drupal\sms\Gateway\GatewayManagerInterface
+   */
+  protected $gatewayManager;
+
+  /**
+   * Creates new Gateway default selection form.
+   */
+  public function __construct(ConfigFactoryInterface $config_factory, GatewayManagerInterface $gateway_manager) {
+    $this->setConfigFactory($config_factory);
+    $this->gatewayManager = $gateway_manager;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('config.factory'),
+      $container->get('plugin.manager.sms_gateway')
+    );
+  }
+
   /**
    * {@inheritdoc}
    */
@@ -28,12 +57,14 @@ class GatewayDefaultForm extends ConfigFormBase {
    */
   public function buildForm(array $form, FormStateInterface $form_state) {
     $form = parent::buildForm($form, $form_state);
-    $gateways = sms_gateways();
-    $default = sms_default_gateway_id();
+    /** @var \Drupal\sms\Gateway\GatewayInterface[] $gateways */
+    $gateways = $this->gatewayManager->getAvailableGateways();
+    $default = $this->gatewayManager->getDefaultGateway();
 
     $form['gateways'] = array(
       '#type' => 'table',
       '#header' => array(
+        $this->t('Enabled'),
         $this->t('Default'),
         $this->t('Name'),
         array(
@@ -47,41 +78,79 @@ class GatewayDefaultForm extends ConfigFormBase {
     );
     foreach ($gateways as $identifier => $gateway) {
       $form['gateways'][$identifier] = array(
+        'enabled' => [
+          '#type' => 'checkbox',
+          '#default_value' => $gateway->isEnabled(),
+          // The checkbox should be disabled if this gateway is the default.
+          // @todo Needs tests.
+          '#states' => [
+            'disabled' => [
+              ':input[name="default"]' => ['value' => $identifier],
+            ],
+          ],
+        ],
         'default' => [
           '#name' => 'default',
           '#type' => 'radio',
-          '#default_value' => $default,
+          '#default_value' => ($default && $default->getName() ==  $identifier),
           '#return_value' => $identifier,
+          // The radio button should be disabled if this gateway not enabled.
+          // @todo Needs tests.
+          '#states' => [
+            'disabled' => [
+              ':input[name="gateways[' . $identifier . '][enabled]"]' => ['checked' => FALSE],
+            ],
+          ],
+        ],
+        'name' => [
+          '#markup' => SafeMarkup::checkPlain($gateway->getLabel()),
         ],
-        'name' => ['#markup' => SafeMarkup::checkPlain($gateway['name'])],
       );
-      if (isset($gateway['configure form']) && function_exists($gateway['configure form'] )) {
-        $form['gateways'][$identifier]['configure'] = ['#markup' => $this->l($this->t('configure'), Url::fromRoute('sms.gateway_config', ['gateway_id' => $identifier]))];
+      if ($gateway->isConfigurable()) {
+        $form['gateways'][$identifier]['configure'] = [
+          '#type' => 'link',
+          '#title' => $this->t('configure'),
+          '#url' => Url::fromRoute('sms.gateway_config', ['gateway_id' => $identifier]),
+        ];
       }
       else {
-        $form['gateways'][$identifier]['configure'] = array('#markup' => $this->t('No configuration options'));
+        $form['gateways'][$identifier]['configure'] = [
+          '#markup' => $this->t('No configuration options')
+        ];
       }
     }
-    $form['actions']['submit']['#value'] = $this->t('Set default gateway');
+    $form['actions']['submit']['#value'] = $this->t('Save settings');
     return $form;
   }
 
   public function validateForm(array &$form, FormStateInterface $form_state) {
-    $form_state->setValue('default', $form_state->getUserInput()['default']);
+    if (empty($form_state->getUserInput()['default'])) {
+      $form_state->setErrorByName('default', $this->t('Default gateway must be set.'));
+    }
+    else {
+      $form_state->setValue('default', $form_state->getUserInput()['default']);
+    }
   }
   
   /**
    * {@inheritdoc}
    */
   public function submitForm(array &$form, FormStateInterface $form_state) {
+    // Set the enabled status of the gateways.
+    $new_default = $form_state->getValue('default');
+    foreach ($form_state->getValue('gateways') as $identifier => $config) {
+      $gateway = $this->gatewayManager->getGateway($identifier);
+      // Selected default gateway is automatically enabled.
+      if ($gateway->getName() === $new_default) {
+        $config['enabled'] = TRUE;
+      }
+      $gateway->setEnabled($config['enabled']);
+      $this->gatewayManager->saveGateway($gateway);
+    }
     // Process form submission to set the default gateway.
-    $default = $form_state->getValue('default');
-    if (sms_gateways('name', $default)) {
+    if ($this->gatewayManager->getGateway($new_default)) {
       drupal_set_message($this->t('Default gateway updated.'));
-
-      $this->config('sms.settings')
-        ->set('default_gateway', $default)
-        ->save();
+      $this->gatewayManager->setDefaultGateway($new_default);
     }
   }
 
diff --git a/src/Gateway/GatewayBase.php b/src/Gateway/GatewayBase.php
index 75be6e4..75b8cce 100644
--- a/src/Gateway/GatewayBase.php
+++ b/src/Gateway/GatewayBase.php
@@ -7,48 +7,57 @@
 
 namespace Drupal\sms\Gateway;
 
-use Drupal\Component\Utility\NestedArray;
+use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Plugin\PluginBase;
+use Drupal\Core\StringTranslation\StringTranslationTrait;
 
 /**
  * Base class for sms gateway plugins.
  */
 abstract class GatewayBase extends PluginBase implements GatewayInterface {
+
+  /**
+   * The watchdog logger for this gateway.
+   *
+   * @var \Psr\Log\LoggerInterface.
+   */
+  protected $logger;
+
   /**
    * Construct a new SmsGateway plugin
    *
-   * @param array
+   * @param array $configuration
    *   The configuration to use and build the sms gateway.
-   * @param string
+   * @param string $plugin_id
    *   The gateway id.
-   * @param mixed
+   * @param mixed $plugin_definition
    *   The gateway plugin definition.
    */
   public function __construct(array $configuration, $plugin_id, $plugin_definition) {
     parent::__construct($configuration, $plugin_id, $plugin_definition);
     $this->configuration = $this->configuration + $this->defaultConfiguration();
+    $this->configuration['custom'] = [];
   }
 
   /**
    * {@inheritdoc}
    */
   public function getIdentifier() {
-    return $this->pluginDefinition['id'];
+    return $this->configuration['name'];
   }
 
   /**
-  /**
    * {@inheritdoc}
    */
   public function getName() {
-    return $this->getLabel();
+    return $this->configuration['name'];
   }
 
   /**
    * {@inheritdoc}
    */
   public function getLabel() {
-    return $this->pluginDefinition['label'];
+    return $this->configuration['label'];
   }
 
   /**
@@ -68,11 +77,31 @@ abstract class GatewayBase extends PluginBase implements GatewayInterface {
   /**
    * {@inheritdoc}
    */
+  public function getCustomConfiguration() {
+    return $this->configuration['custom'];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setCustomConfiguration($configuration) {
+    $this->configuration['custom'] = $configuration;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
   public function defaultConfiguration() {
-    return array(
-      'use_ssl' => FALSE,
-      'send_method' => 'HTTP_POST',
-    );
+    return [
+      'plugin_id' => $this->pluginDefinition['id'],
+      'name' => $this->pluginDefinition['id'],
+      'label' => (string) $this->pluginDefinition['label'],
+      'enabled' => FALSE,
+      'custom' => [
+        'use_ssl' => FALSE,
+        'send_method' => 'HTTP_POST',
+      ]
+    ];
   }
 
   /**
@@ -85,28 +114,67 @@ abstract class GatewayBase extends PluginBase implements GatewayInterface {
   /**
    * {@inheritdoc}
    */
-  public function buildConfigurationForm(array $form, array &$form_state) {
+  public function buildConfigurationForm(array $form, FormStateInterface $form_state) {
     return $form;
   }
 
   /**
    * {@inheritdoc}
    */
-  public function validateConfigurationForm(array &$form, array &$form_state) {
+  public function validateConfigurationForm(array &$form, FormStateInterface $form_state) {
     return;
   }
 
   /**
    * {@inheritdoc}
    */
-  public function submitConfigurationForm(array &$form, array &$form_state) {
+  public function submitConfigurationForm(array &$form, FormStateInterface $form_state) {
     return;
   }
 
   /**
    * {@inheritdoc}
    */
-  public function sendForm(array &$form, array &$form_state) {
+  public function sendForm(array &$form, FormStateInterface $form_state) {
     return array();
   }
-}
\ No newline at end of file
+
+  /**
+   * {@inheritdoc}
+   */
+  public function isEnabled() {
+    return isset($this->configuration['enabled']) ? $this->configuration['enabled'] : FALSE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setEnabled($enabled = TRUE) {
+    $this->configuration['enabled'] = (bool) $enabled;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function calculateDependencies() {
+    return [];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validateNumbers(array $numbers, array $options = array()) {
+    return [];
+  }
+
+  /**
+   * Gets the Psr logger for this gateway.
+   */
+  protected function logger() {
+    if (!isset($this->logger)) {
+      $this->logger = \Drupal::logger($this->getName());
+    }
+    return $this->logger;
+  }
+
+}
diff --git a/src/Gateway/GatewayDefaultImpl.php b/src/Gateway/GatewayDefaultImpl.php
deleted file mode 100644
index 7a94328..0000000
--- a/src/Gateway/GatewayDefaultImpl.php
+++ /dev/null
@@ -1,321 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\sms\Plugin\Gateway\GatewayDefaultImpl
- */
-
-namespace Drupal\sms\Gateway;
-
-use Drupal\sms\Message\Message;
-use Drupal\sms\Message\MessageInterface;
-use Drupal\sms\Message\MessageResult;
-use Symfony\Component\HttpFoundation\Request;
-
-/**
- * Provides a default implementation of the Gateway interface with additional
- * helper functions.
- *
- * Most gateways should subclass this for easier implementations.
- */
-abstract class GatewayDefaultImpl extends GatewayBase {
-  /**
-   * {@inheritdoc}
-   */
-  public function send(MessageInterface $sms, array $options) {
-    // Wrapper method for sending messages.
-    // Provides basic cleanup functionality prior to passing onto gateway send
-    // command. Subclasses will implement additional logic in the doSend() method
-    // and also call the doCommand('send') method to dispatch messages.
-
-    // Call subclass implementation to process sending.
-    $res = $this->doSend($sms, $options);
-
-    // Invoke sms framework message receipt handlers
-    // @todo Need to re-look this implementation
-    foreach ($res as $num => $response) {
-      @$options += array(
-        'gateway_message_status' => $response['error map'],
-        'gateway_message_status_text' => $response['error'],
-        'gateway_message_status_original' => $response['error code'],
-        'gateway' => $this->getName(),
-      );
-      @sms_receipt($num, $response['message id'], $response['message status'], $options);
-    }
-    return $res;
-  }
-
-
-  /**
-   * {@inheritdoc}
-   */
-  public function balance() {
-    $result = $this->doCommand('credits', array());
-    return isset($result['credit_balance']) ? $result['credit_balance'] : 0;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function deliveryReport(Request $request) {
-    return;
-  }
-
-  /**
-   * Provide delivery reports return path for this gateway
-   * @todo Needs work.
-   */
-  protected function deliveryPath($absolute=TRUE) {
-    $path = 'sms/deliveryreport/' . $this->getName();
-    if ($absolute) {
-      $path = url($path, array('absolute' => TRUE));
-    }
-    return $path;
-  }
-
-  /**
-   * Tests the gateway.
-   *
-   * @param array $config
-   *    Optional configuration parameters to test gateway with.
-   * @return TRUE / FALSE if gateway is through
-   */
-  function test(array $config = array()) {
-    $result = $this->doCommand('test', array(), $config);
-    return $result['status'];
-  }
-
-  /**
-   * Handles the low-level connection for sending messages.
-   *
-   * This method implicitly handles the splitting of messages into smaller
-   * batches if the number of recipients are too much for a standard HTTP-GET
-   * or HTTP-POST payload.
-   *
-   * @see doSplitSend()
-   *
-   * @param Message $message
-   *   The sms message to be sent.
-   * @param $options
-   *   Additional options.
-   * @return \Drupal\sms\Message\MessageResult
-   *   The result of the sms messaging operation.
-   *
-   * @return array(
-   *     'status'  => TRUE | FALSE,
-   *     'message' => '<message to display if status above is FALSE>',
-   *     'report'  => array(
-   *       '<number>' => array(
-   *         'status' => TRUE | FALSE   // Essentially TRUE if there is a message id
-   *         'message_id' => '<message id>',
-   *         'error_code' => '<sms framework error code>',
-   *         'error_message' => '<sms framework error message>',
-   *         'gateway_error_code' => '<gateway error code>',
-   *         'gateway_error_message' => '<gateway error message>'
-   *       ),
-   *     'credit_used' => '<credits used>',
-   *     'credit_balance' => '<credits remaining>',
-   *   );
-   *
-   * Notes: 'status' of TRUE means successful communication with the sms server and success in message request. Failure of
-   *  individual messages will be captured in the message report status for that number.
-   */
-  protected function doSend(Message $message, array $options) {
-    return $this->doSplitSend($message, $options);
-  }
-
-  /**
-   * Splits and sends messages in batches to recipients.
-   *
-   * This method splits messages into smaller batches to avoid exceeding HTTP-GET
-   * and HTTP-POST data size limits which may cause timeouts, truncated messages,
-   * and other sorts of wierd behavior depending on the web server.
-   *
-   * @param \Drupal\sms\Message\Message $sms
-   *   The message to be sent.
-   * @param array $options
-   *   Options to be applied while processing this sms.
-   * @param $maxsize int
-   *   Optional - maximum size of each batch to send.
-   * @return \Drupal\sms\Message\MessageResult
-   *   The composite MessageResult object.
-   */
-  protected function doSplitSend(Message $sms, array $options, $maxsize = 400) {
-    // Initialize the composite results array.
-    $all_res = array(
-      'status' => FALSE,
-      'error_message' => '',
-      'credit_used' => 0,
-      'credit_balance' => 0,
-      'report' => array(),
-    );
-    $recipients = $sms->getRecipients();
-    while (count($recipients) > 0) {
-      $this_batch = array_slice($recipients, 0, $maxsize);
-      $recipients = array_slice($recipients, $maxsize);
-      if (!empty($this_batch)) {
-        $res = $this->doCommand('send', array('recipients' => $this_batch, 'message' => $sms->getMessage()), $options);
-        // Combine $res with existing $all_res
-        @$all_res['status'] |= $res['status'];
-        @$all_res['error_message'] .= "\n" . $res['message'];
-        @$all_res['credit_used'] += $res['credit_used'];
-        @$all_res['credit_balance'] = $res['credit_balance'];
-        @$all_res['report'] += (array)$res['report'];
-      }
-    }
-    return new MessageResult($all_res);
-  }
-
-  /**
-   * Generates random message id's for gateways that don't autogenerate
-   */
-  protected function randomID() {
-    if (!isset($this->sessid)) {
-      $this->sessid = str_pad(rand(0, 99), 2, '0', STR_PAD_LEFT);
-    }
-    return time() . $this->sessid . str_pad(rand(0, 99999), 5, '0', STR_PAD_LEFT);
-  }
-
-  /**
-   * Handles the low-level transmission of messages.
-   *
-   * @param string $command
-   *   The command to be executed.
-   * @param array $data
-   *   An array containing the data pertaining to the message. Information that
-   *   can be in this array is as follows:
-   *   - recipients: An array of recipient numbers.
-   *   - message: The sms message to be dispatched.
-   *   -
-   * @param array $options
-   *   Optional - additional options for sending the message.
-   *
-   * @see \Drupal\sms\Gateway\GatewayInterface::send() for structure of return value
-   */
-  abstract protected function doCommand($command, array $data, array $options = array());
-
-  /**
-   * Cleans up message and removes non-compatible characters.
-   *
-   * @param string $message
-   *   The message to be cleaned up.
-   * @return string
-   *   The cleaned up message.
-   */
-  protected function cleanMessage($message) {
-    $search = str_split('ëí`ìî');
-    $replace = str_split('\'\'\'""');
-    $message = str_replace($search, $replace, $message);
-    $message = urlencode($message);
-    return $message;
-  }
-
-  /**
-   * Cleans up sender id and removes non-compatible characters.
-   *
-   * @param string $sender
-   *   The sender id to be cleaned up.
-   * @return string
-   *   The cleaned up sender.
-   */
-  protected function cleanSender($sender) {
-    return str_replace(' ', '', urlencode(substr($sender, 0, 12)));
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function defaultConfiguration() {
-    return array(
-      'ssl' => '',
-      'server' => '',
-      'username' => '',
-      'password' => '',
-      'method' => '',
-    ) + parent::defaultConfiguration();
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function buildConfigurationForm(array $form, array &$form_state) {
-    $config = $this->getConfiguration();
-
-    $t_args = array(
-      '@name' => $this->getName(),
-      '@label' => $this->getLabel(),
-    );
-
-    $form['balance'] = array(
-      '#type' => 'item',
-      '#title' => $this->t('Current balance'),
-      '#markup' => $this->balance(),
-    );
-    $form['method'] = array(
-      '#type' => 'radios',
-      '#title' => $this->t('Send Method'),
-      '#description' => $this->t('The method to use for sending sms.'),
-      '#options' => array(
-        $this->t('HTTP GET (Split server request if recipients > 400)'),
-        $this->t('HTTP GET (Use POST if recipients > 500)'),
-        $this->t('HTTP POST'),
-//        $this->t('SMPP (Not yet implemented)'),
-      ),
-      '#default_value' => $config['method'],
-    );
-    $form['ssl'] = array(
-      '#type' => 'checkbox',
-      '#title' => $this->t('Use SSL Encyption'),
-      '#description' => $this->t('Drupal\'s built-in HTTP client only supports SSL on PHP 4.3 compiled with OpenSSL.'),
-      '#default_value' => $config['ssl'],
-    );
-    $form['server'] = array(
-      '#type' => 'textfield',
-      '#title' => $this->t('API Server URL'),
-      '#description' => $this->t('The url for accessing the @label api server.', $t_args),
-      '#size' => 40,
-      '#maxlength' => 255,
-      '#default_value' => $config['server'],
-    );
-    $form['username'] = array(
-      '#type' => 'textfield',
-      '#title' => $this->t('Username'),
-      '#description' => $this->t('The username on the @label account.', $t_args),
-      '#size' => 40,
-      '#maxlength' => 255,
-      '#default_value' => $config['username'],
-    );
-    // @todo should this be a password (masked) text input?????
-    $form['password'] = array(
-      '#type' => 'textfield',
-      '#title' => $this->t('Password'),
-      '#description' => $this->t('The current password on the @label account.', $t_args),
-      '#size' => 30,
-      '#maxlength' => 64,
-      '#default_value' => $config['password'],
-    );
-    return $form;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function validateConfigurationForm(array &$form, array &$form_state) {
-    if (!$this->test($form_state['values'])) {
-      $error = $this->getError();
-      form_set_error($error['form_element'], t('The settings could not be validated. A gateway error occurred: @error.',
-        array('@error' => $error['description'])));
-    }
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function submitConfigurationForm(array &$form, array &$form_state) {
-    $this->configuration['method'] = $form_state['values']['method'];
-    $this->configuration['ssl'] = $form_state['values']['ssl'];
-    $this->configuration['server'] = $form_state['values']['server'];
-    $this->configuration['username'] = $form_state['values']['username'];
-    $this->configuration['password'] = $form_state['values']['password'];
-  }
-}
diff --git a/src/Gateway/GatewayInterface.php b/src/Gateway/GatewayInterface.php
index 0c841bb..9d3aea8 100644
--- a/src/Gateway/GatewayInterface.php
+++ b/src/Gateway/GatewayInterface.php
@@ -8,17 +8,19 @@
 namespace Drupal\sms\Gateway;
 
 use Drupal\Component\Plugin\ConfigurablePluginInterface;
+use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Plugin\PluginFormInterface;
-use Drupal\sms\Message\Message;
-use Drupal\sms\Message\MessageInterface;
+use Drupal\sms\Message\SmsMessageInterface;
 use Symfony\Component\HttpFoundation\Request;
 
 /**
  * Default implementation of sms gateway plugin
  */
 interface GatewayInterface extends ConfigurablePluginInterface, PluginFormInterface {
+
   // Gateway response codes
   // 0=Unknown, 2xx=Positive, 4xx=Negative(likely client err), 5xx=Negative(likely gateway err)
+
   /**
    * Status Unknown.
    *
@@ -123,14 +125,15 @@ interface GatewayInterface extends ConfigurablePluginInterface, PluginFormInterf
   /**
    * Sends an sms and invokes the corresponding sms receipt method.
    *
-   * @param \Drupal\sms\Message\MessageInterface $sms
+   * @param \Drupal\sms\Message\SmsMessageInterface $sms
    *   The sms to be sent.
    * @param array $options
    *   Options to be applied while processing this sms.
-   * @return \Drupal\sms\Message\MessageResultInterface
+   *
+   * @return \Drupal\sms\Message\SmsMessageResultInterface
    *   The result of the sms messaging operation.
    */
-  public function send(MessageInterface $sms, array $options);
+  public function send(SmsMessageInterface $sms, array $options);
 
   /**
    * Returns the credit balance available on this gateway.
@@ -140,7 +143,7 @@ interface GatewayInterface extends ConfigurablePluginInterface, PluginFormInterf
   public function balance();
 
   /**
-   * Handles delivery reports and invoke the corresponding sms_receipt method
+   * Handles delivery reports and invokes the corresponding sms_receipt method.
    *
    * @param \Symfony\Component\HttpFoundation\Request
    *   Request object containing the delivery report in raw format.
@@ -165,7 +168,6 @@ interface GatewayInterface extends ConfigurablePluginInterface, PluginFormInterf
   public function getIdentifier();
 
   /**
-  /**
    * Gets the readable name of the gateway.
    *
    * @return string
@@ -197,5 +199,44 @@ interface GatewayInterface extends ConfigurablePluginInterface, PluginFormInterf
    * @returns array
    *   The form for additional gateway-specific sending options.
    */
-  public function sendForm(array &$form, array &$form_state);
-}
\ No newline at end of file
+  public function sendForm(array &$form, FormStateInterface $form_state);
+
+  /**
+   * Gets the enabled status of the gateway.
+   *
+   * @return bool
+   */
+  public function isEnabled();
+
+  /**
+   * Sets the enabled status of the gateway.
+   *
+   * @param bool $status
+   *   The enabled status.
+   */
+  public function setEnabled($status = TRUE);
+
+  /**
+   * Gets the plugin-specific configuration for this gateway.
+   */
+  public function getCustomConfiguration();
+
+  /**
+   * Sets the plugin-specific configuration for this gateway.
+   */
+  public function setCustomConfiguration($configuration);
+
+  /**
+   * Carry out gateway-specific number validation.
+   *
+   * @param array $numbers
+   *   The list of phone numbers to be validated.
+   * @param array $options
+   *   Options to be considered for validation.
+   *
+   * @return array
+   *   An array containing an error message for each validation failure.
+   */
+  public function validateNumbers(array $numbers, array $options = array());
+
+}
diff --git a/src/Gateway/GatewayManager.php b/src/Gateway/GatewayManager.php
index bcb9f33..7b77bd6 100644
--- a/src/Gateway/GatewayManager.php
+++ b/src/Gateway/GatewayManager.php
@@ -7,15 +7,16 @@
 
 namespace Drupal\sms\Gateway;
 
+use Drupal\Core\Cache\CacheBackendInterface;
 use Drupal\Core\Config\ConfigFactory;
 use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\Core\Plugin\DefaultPluginManager;
-use Drupal\sms\Gateway\HookGateway;
 
 /**
  * Manages SMS gateways implemented using AnnotatedClassDiscovery
  */
 class GatewayManager extends DefaultPluginManager implements GatewayManagerInterface {
+
   /**
    * Configuration factory for this gateway manager.
    *
@@ -38,14 +39,6 @@ class GatewayManager extends DefaultPluginManager implements GatewayManagerInter
   protected $names;
 
   /**
-   * List of the gateways that have been enabled.
-   *
-   * A list of gateway labels is keyed by the gateway ids (names)
-   * @var array
-   */
-  protected $enabledGateways;
-
-  /**
    * The default gateway.
    *
    * @var string
@@ -59,17 +52,23 @@ class GatewayManager extends DefaultPluginManager implements GatewayManagerInter
    *   The namespaces to search for the gateway plugins.
    * @param \Drupal\Core\Config\ConfigFactory
    *   Handles the instantiation of gateways based on stored configuration.
+   * @param \Drupal\Core\Cache\CacheBackendInterface $cache_backend
+   *   Cache backend instance to use.
    * @param \Drupal\Core\Extension\ModuleHandlerInterface
    *   Module handler for calling module hooks.
    */
-  public function __construct(\Traversable $namespaces, ConfigFactory $config, ModuleHandlerInterface $module_handler) {
-    parent::__construct('Plugin/Gateway', $namespaces, $module_handler, 'Drupal\sms\Annotation\SmsGateway');
-//    $this->setCacheBackend($cache_backend, $language_manager, 'mail_backend_plugins');
+  public function __construct(\Traversable $namespaces, ConfigFactory $config, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler) {
+    parent::__construct('Plugin/Gateway', $namespaces, $module_handler, 'Drupal\sms\Gateway\GatewayInterface', 'Drupal\sms\Annotation\SmsGateway');
+    $this->setCacheBackend($cache_backend, 'sms_gateways');
+    $this->alterInfo('sms_gateway_info');
     $this->config = $config;
-    $this->enabledGateways = $this->config->get('sms.settings')->get('enabled_gateways');
     $this->defaultGateway = $this->config->get('sms.settings')->get('default_gateway');
   }
 
+  public function getGatewayPlugins() {
+    return $this->discovery->getDefinitions();
+  }
+
   /**
    * {@inheritdoc}
    */
@@ -100,14 +99,15 @@ class GatewayManager extends DefaultPluginManager implements GatewayManagerInter
    */
   public function setDefaultGateway($gateway_id) {
     // Cannot make a disabled gateway default.
-    if (!$this->enabledGateways[$gateway_id]) {
-      return;
+    if ($this->getGateway($gateway_id)->isEnabled()) {
+      $this->defaultGateway = $gateway_id;
+      $this->config->getEditable('sms.settings')
+        ->set('default_gateway', $this->defaultGateway)
+        ->save();
+    }
+    else {
+      throw new \LogicException('A disabled gateway cannot be made the default.');
     }
-    $this->defaultGateway = $gateway_id;
-
-    $this->config->get('sms.settings')
-      ->set('default_gateway', $this->defaultGateway)
-      ->save();
   }
 
   /**
@@ -124,49 +124,53 @@ class GatewayManager extends DefaultPluginManager implements GatewayManagerInter
    * {@inheritdoc}
    */
   public function getEnabledGateways() {
-    if (!isset($this->enabledGateways)) {
-      $this->enabledGateways = $this->config->get('sms.settings')
-        ->get('enabled_gateways');
-    }
-    if (!isset($this->enabledGateways)) {
-      $this->enabledGateways = array();
-    }
-
-    // Ensure gateway list has been built.
-    $gateways = $this->getAvailableGateways();
-
-    return array_intersect_key($gateways, $this->enabledGateways);
+    return array_filter($this->getAvailableGateways(), function(GatewayInterface $gateway) {
+      $gateway->isEnabled();
+    });
   }
 
   /**
    * {@inheritdoc}
    */
   public function setEnabledGateways(array $gateways) {
-    $gateways = array_intersect($gateways, array_keys($this->getAvailableGateways()));
-    $this->enabledGateways = array_fill_keys($gateways, TRUE);
-    $this->config->get('sms.settings')
-      ->set('enabled_gateways', $this->enabledGateways)
-      ->save();
+    foreach ($gateways as $gateway_id) {
+      $gateway = $this->getGateway($gateway_id);
+      $gateway->setEnabled(TRUE);
+      $this->saveGateway($gateway);
+    }
   }
 
   /**
    * {@inheritdoc}
    */
   public function isGatewayEnabled($gateway_id) {
-    return !empty($this->enabledGateways[$gateway_id]);
+    return $this->getGateway($gateway_id)->isEnabled();
   }
 
   /**
    * {@inheritdoc}
    */
-  public function saveConfiguration($gateway) {
-    if (is_string($gateway)) $gateway = $this->getGateway($gateway);
-    $this->config->get('sms.gateway.config')
+  public function saveGateway(GatewayInterface $gateway) {
+    $this->config->getEditable('sms.gateway.config')
       ->set($gateway->getName(), $gateway->getConfiguration())
       ->save();
   }
 
   /**
+   * {@inheritdoc}
+   */
+  public function addGateway($plugin_id, array $configuration) {
+    $name = $configuration['name'];
+    if (!isset($configuration['name'])) {
+      throw new \InvalidArgumentException('A machine name is required to create an SMS gateway.');
+    }
+    $configuration['plugin_id'] = $plugin_id;
+    $this->gateways[$name] = $gateway = $this->createInstance($plugin_id, $configuration);
+    $this->names[$name] = $this->gateways[$name]->getLabel();
+    $this->saveGateway($gateway);
+  }
+
+  /**
    * Builds the gateway plugin objects from the definitions.
    *
    * @return array
@@ -175,25 +179,42 @@ class GatewayManager extends DefaultPluginManager implements GatewayManagerInter
    * @todo remove BC-shim when all gateways are converted to plugins.
    */
   protected function buildGateways() {
+    // Non-configurable gateways do not need configuration and so should be
+    // available by default.
+    // Get non-configurable plugins and set them up if not already done.
     $definitions = $this->getDefinitions();
-    foreach ($definitions as $id => $definition) {
-      $settings = $this->config->get('sms.gateway.config')->get($id);
+    $plugin_config = [];
+    foreach ($definitions as $plugin_id => $definition) {
+      if (!$definition['configurable']) {
+        $plugin_config[$plugin_id] = ['plugin_id' => $plugin_id];
+      }
+    }
+
+    // Get configured gateways.
+    $instance_configs = $this->config->get('sms.gateway.config')->getRawData();
+    $instance_configs += $plugin_config;
+    foreach ($instance_configs as $id => $instance_config) {
       // Note that DefaultFactory::createInstance will get the right definitions.
-      if (!isset($settings)) $settings = array();
-      $this->gateways[$id] = $this->createInstance($id, $settings);
+      if (!isset($instance_config['plugin_id'])) {
+        // @todo Throw exception here???
+//        throw new \InvalidArgumentException(sprintf('Gateway %s configured without a plugin id.', $id));
+        continue;
+      }
+      $this->gateways[$id] = $this->createInstance($instance_config['plugin_id'], $instance_config);
       $this->names[$id] = $this->gateways[$id]->getLabel();
     }
 
+
     // BC-shim for gateways still based on hook_gateway_info implementation.
-    $gateway_array = \Drupal::moduleHandler()->invokeAll('gateway_info');
+    $gateway_array = $this->moduleHandler->invokeAll('gateway_info');
+    $gateway_configs = $this->config->get('sms.gateway.config');
     foreach ($gateway_array as $id => $info) {
-      $settings = $this->config->get('sms.gateway.config')->get($id);
+      $settings = $gateway_configs->get($id);
       if (!isset($settings)) $settings = array();
+      $info['identifier'] = $id;
       $this->gateways[$id] = new HookGateway($info, $settings);
       $this->names[$id] = $this->gateways[$id]->getLabel();
     }
-
-    // Is this needed??
-    asort($this->names);
   }
-}
\ No newline at end of file
+
+}
diff --git a/src/Gateway/GatewayManagerInterface.php b/src/Gateway/GatewayManagerInterface.php
index af296de..5c173ec 100644
--- a/src/Gateway/GatewayManagerInterface.php
+++ b/src/Gateway/GatewayManagerInterface.php
@@ -10,6 +10,7 @@ namespace Drupal\sms\Gateway;
  * Manages SMS Gateways.
  */
 interface GatewayManagerInterface {
+
   /**
    * Get the list of all discoverable SMS gateways.
    *
@@ -67,10 +68,33 @@ interface GatewayManagerInterface {
   public function isGatewayEnabled($gateway_id);
 
   /**
+   * Creates a new gateway of a type from specified configuration.
+   *
+   * @param string $plugin_id
+   *   The plugin ID of an existing gateway plugin.
+   * @param array $configuration
+   *   The configuration to be saved for the gateway. At a minimum must contain:
+   *   - name: The machine name of the gateway
+   *   - label: The human-readable name of the gateway
+   *
+   * @return \Drupal\sms\Gateway\GatewayInterface
+   *   A newly created gateway instance.
+   */
+  public function addGateway($plugin_id, array $configuration);
+
+  /**
    * Saves the configuration of a gateway.
    *
-   * @param \Drupal\sms\Gateway\GatewayInterface|string
-   *   The gateway whose configuration is to be saved.
+   * @param \Drupal\sms\Gateway\GatewayInterface
+   *   The gateway object whose configuration is to be saved.
    */
-  public function saveConfiguration($gateway);
-}
\ No newline at end of file
+  public function saveGateway(GatewayInterface $gateway);
+
+  /**
+   * Gets the list of gateway plugins discovered by this gateway manager.
+   *
+   * @return \Drupal\sms\Gateway\GatewayInterface[]
+   */
+  public function getGatewayPlugins();
+
+}
diff --git a/src/Gateway/HookGateway.php b/src/Gateway/HookGateway.php
index f9da4d1..a57092c 100644
--- a/src/Gateway/HookGateway.php
+++ b/src/Gateway/HookGateway.php
@@ -7,48 +7,39 @@
 
 namespace Drupal\sms\Gateway;
 
-use Drupal\Component\Plugin\Discovery\DiscoveryTrait;
-use Drupal\Core\StringTranslation\StringTranslationTrait;
-use Drupal\sms\Message\MessageInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\sms\Message\SmsMessageInterface;
+use Drupal\sms\Message\SmsMessageResult;
 use Symfony\Component\HttpFoundation\Request;
 
 /**
  * BC-shim class to allow hook_gateway_info() based gateways to still work.
  */
-class HookGateway implements GatewayInterface {
-
-  use StringTranslationTrait;
-
-  /**
-   * The info that was pulled out from hook implementations.
-   *
-   * @var array
-   */
-  protected $info = array();
+class HookGateway extends GatewayBase {
 
   /**
-   * The settings (configuration) that was saved in config.
+   * Constructs a new hook-based gateway.
    *
-   * @var array
-   */
-  protected $settings = array();
-
-  /**
    * @param array $info
    *   The info extracted from hook_gateway_info() for this gateway.
-   * @param array $settings
+   * @param array $configuration
    *   The settings stored in config for this gateway.
    */
-  public function __construct(array $info, array $settings) {
-    $this->info = $info;
-    $this->settings = $settings;
+  public function __construct(array $info, array $configuration) {
+    $this->configuration = $configuration + ['custom' => []];
+    $this->pluginId = 'sms_hook_gateway';
+    $this->pluginDefinition = $info;
   }
 
   /**
    * {@inheritdoc}
    */
-  public function send(MessageInterface $sms, array $options) {
-    if (is_callable($this->info['send'])) $this->info['send']($sms, $options);
+  public function send(SmsMessageInterface $sms, array $options) {
+    if (is_callable($this->pluginDefinition['send'])) {
+      $result = $this->pluginDefinition['send']($sms, $options);
+      return new SmsMessageResult($result);
+    }
+    throw new \BadMethodCallException(sprintf('No send method defined for gateway %s', $this->configuration['name']));
   }
 
   /**
@@ -73,75 +64,41 @@ class HookGateway implements GatewayInterface {
   }
 
   /**
-   * {@inheritdoc}
-   */
-  public function getConfiguration() {
-    return $this->settings;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function setConfiguration(array $configuration) {
-    $this->settings = $configuration;
-  }
-
-  /**
-   * Returns default configuration for this plugin.
-   *
-   * @return array
-   *   An associative array with the default configuration.
-   */
-  public function defaultConfiguration() {
-    return array(
-      'use_ssl' => FALSE,
-      'send_method' => 'HTTP_POST',
-    );
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function calculateDependencies() {
-    return array();
-  }
-
-  /**
    * Gets the machine  name of the gateway.
    *
    * @return string
    */
   public function getIdentifier() {
-    return $this->info['identifier'];
+    return $this->pluginDefinition['identifier'];
   }
 
   /**
    * {@inheritdoc}
    */
   public function getName() {
-    return $this->info['name'];
+    return $this->pluginDefinition['identifier'];
   }
 
   /**
    * {@inheritdoc}
    */
   public function getLabel() {
-    return $this->getName();
+    return $this->pluginDefinition['name'];
   }
 
   /**
    * {@inheritdoc}
    */
   public function isConfigurable() {
-    return isset($this->info['configure form']) && is_callable($this->info['configure form']);
+    return isset($this->pluginDefinition['configure form']) && is_callable($this->pluginDefinition['configure form']);
   }
 
   /**
    * {@inheritdoc}
    */
-  public function buildConfigurationForm(array $form, array &$form_state) {
-    if (is_callable($this->info['configure form'])) {
-      return $this->info['configure form']($form, $form_state);
+  public function buildConfigurationForm(array $form, FormStateInterface $form_state) {
+    if (is_callable($this->pluginDefinition['configure form'])) {
+      return array_merge($form, $this->pluginDefinition['configure form']($this->getCustomConfiguration()));
     }
     else {
       throw new \RuntimeException($this->t('Configuration form callback not available.'));
@@ -151,28 +108,46 @@ class HookGateway implements GatewayInterface {
   /**
    * {@inheritdoc}
    */
-  public function validateConfigurationForm(array &$form, array &$form_state) {
-    $function = $this->info['configure form'] . '_validate';
+  public function validateConfigurationForm(array &$form, FormStateInterface $form_state) {
+    $function = $this->pluginDefinition['configure form'] . '_validate';
     if (is_callable($function)) $function($form, $form_state);
   }
 
   /**
    * {@inheritdoc}
    */
-  public function submitConfigurationForm(array &$form, array &$form_state) {
-    $function = $this->info['configure form'] . '_submit';
-    if (is_callable($function)) $function($form, $form_state);
+  public function submitConfigurationForm(array &$form, FormStateInterface $form_state) {
+    $function = $this->pluginDefinition['configure form'] . '_submit';
+    if (is_callable($function)) {
+      // Call the hook gateway submit callback.
+      $function($form, $form_state);
+    }
+    // Update the configuration.
+    $this->setCustomConfiguration($form_state->getValues());
   }
 
   /**
    * {@inheritdoc}
    */
-  public function sendForm(array &$form, array &$form_state) {
-    if (is_callable($this->info['send form'])) {
-      return $this->info['send form']($form, $form_state);
+  public function sendForm(array &$form, FormStateInterface $form_state) {
+    if (is_callable($this->pluginDefinition['send form'])) {
+      return $this->pluginDefinition['send form']($form, $form_state);
     }
     else {
       return array();
     }
   }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validateNumbers(array $numbers, array $options = array()) {
+    if (is_callable($this->pluginDefinition['validate number'])) {
+      return $this->pluginDefinition['validate number']($numbers, $options);
+    }
+    else {
+      return array();
+    }
+  }
+
 }
diff --git a/src/Message/Message.php b/src/Message/SmsMessage.php
similarity index 94%
rename from src/Message/Message.php
rename to src/Message/SmsMessage.php
index edf8c8d..55bcb78 100644
--- a/src/Message/Message.php
+++ b/src/Message/SmsMessage.php
@@ -2,7 +2,7 @@
 
 /**
  * @file
- * Contains \Drupal\sms\Message\Message class
+ * Contains \Drupal\sms\Message\SmsMessage.
  */
 
 namespace Drupal\sms\Message;
@@ -10,7 +10,8 @@ namespace Drupal\sms\Message;
 /**
  * Basic implementation of an sms message.
  */
-class Message implements MessageInterface {
+class SmsMessage implements SmsMessageInterface {
+
   /**
    * The unique identifier for this message.
    *
@@ -99,4 +100,5 @@ class Message implements MessageInterface {
     }
     return NULL;
   }
-}
\ No newline at end of file
+
+}
diff --git a/src/Message/MessageInterface.php b/src/Message/SmsMessageInterface.php
similarity index 89%
rename from src/Message/MessageInterface.php
rename to src/Message/SmsMessageInterface.php
index 86832af..7eccf3c 100644
--- a/src/Message/MessageInterface.php
+++ b/src/Message/SmsMessageInterface.php
@@ -2,7 +2,7 @@
 
 /**
  * @file
- * Contains definition of \Drupal\sms\Message\MessageInterface
+ * Contains definition of \Drupal\sms\Message\SmsMessageInterface
  */
 
 namespace Drupal\sms\Message;
@@ -10,9 +10,11 @@ namespace Drupal\sms\Message;
 /**
  * Contains information about an sms.
  */
-interface MessageInterface {
-// Message status codes
-// 0=Unknown, 2xx=Positive, 3xx=Positive/Neutral (context-dependent), 4xx=Negative
+interface SmsMessageInterface {
+
+  // Message status codes
+  // 0=Unknown, 2xx=Positive, 3xx=Positive/Neutral (context-dependent), 4xx=Negative
+
   /**
    * Status Unknown.
    *
diff --git a/src/Message/MessageResult.php b/src/Message/SmsMessageResult.php
similarity index 85%
rename from src/Message/MessageResult.php
rename to src/Message/SmsMessageResult.php
index 5c3dfce..c21508a 100644
--- a/src/Message/MessageResult.php
+++ b/src/Message/SmsMessageResult.php
@@ -1,7 +1,7 @@
 <?php
 
 /**
- * Contains \Drupal\sms\Message\MessageResult
+ * Contains \Drupal\sms\Message\SmsMessageResult
  */
 
 namespace Drupal\sms\Message;
@@ -10,7 +10,8 @@ namespace Drupal\sms\Message;
 /**
  * The result of an sms messaging transaction.
  */
-class MessageResult implements MessageResultInterface {
+class SmsMessageResult implements SmsMessageResultInterface {
+
   /**
    * The status of the message.
    *
@@ -50,12 +51,12 @@ class MessageResult implements MessageResultInterface {
    * Create a new message result based on data supplied in the array.
    *
    * @param array $data
-   *   Information to be used to instantiate the MessageResult.
+   *   Information to be used to instantiate the SmsMessageResult.
    */
   public function __construct($data) {
     $this->status = $data['status'];
     $this->creditBalance = $data['credit_balance'];
-    $this->creditUsed = $data['credit_used'];
+    $this->creditsUsed = $data['credit_used'];
     $this->errorMessage = $data['error_message'];
     $this->report = $data['report'];
   }
@@ -64,28 +65,28 @@ class MessageResult implements MessageResultInterface {
    * {@inheritdoc}
    */
   public function getStatus() {
-    $this->status;
+    return $this->status;
   }
 
   /**
    * {@inheritdoc}
    */
   public function getReport() {
-    $this->report;
+    return $this->report;
   }
 
   /**
    * {@inheritdoc}
    */
   public function getBalance() {
-    $this->creditBalance;
+    return $this->creditBalance;
   }
 
   /**
    * {@inheritdoc}
    */
   public function getCreditsUsed() {
-    $this->creditsUsed;
+    return $this->creditsUsed;
   }
 
   /**
@@ -121,7 +122,7 @@ class MessageResult implements MessageResultInterface {
    * {@inheritdoc}
    */
   public function getErrorMessage() {
-    $this->errorMessage;
+    return $this->errorMessage;
   }
 
   /**
@@ -129,10 +130,11 @@ class MessageResult implements MessageResultInterface {
    */
   public function getReportFor($recipient) {
     if (isset($this->report[$recipient])) {
-      $this->report[$recipient];
+      return $this->report[$recipient];
     }
     else {
       return null;
     }
   }
-}
\ No newline at end of file
+
+}
diff --git a/src/Message/MessageResultInterface.php b/src/Message/SmsMessageResultInterface.php
similarity index 83%
rename from src/Message/MessageResultInterface.php
rename to src/Message/SmsMessageResultInterface.php
index 9a6e80e..737cb0b 100644
--- a/src/Message/MessageResultInterface.php
+++ b/src/Message/SmsMessageResultInterface.php
@@ -2,13 +2,13 @@
 
 /**
  * @file
- * Contains Drupal\sms\Message\MessageResultInterface
+ * Contains Drupal\sms\Message\SmsMessageResultInterface
  */
 
 namespace Drupal\sms\Message;
 
 /**
- * Contains information on message results.
+ * Contains information on sms message results.
  * @return array(
  *     'status'  => TRUE | FALSE,
  *     'message' => '<message to display if status above is FALSE>',
@@ -25,7 +25,8 @@ namespace Drupal\sms\Message;
  *   );
  *
  */
-interface MessageResultInterface {
+interface SmsMessageResultInterface {
+
   /**
    * Gets the status of the message.
    *
@@ -44,15 +45,15 @@ interface MessageResultInterface {
   public function getErrorMessage();
 
   /**
-   * Gets the report for all recipients.
+   * Gets the delivery report for all recipients.
    *
    * @return array
    *   The report for all recipients. This report is an array keyed by the
    *   recipients' numbers. The value is also an array with the following keys:
    *   - status: TRUE if message was successfully sent, FALSE otherwise.
-   *   - message_id: The message id if the message was successfully sent. Other
-   *     wise 0.
-   *   - error_code: The error code number.
+   *   - message_id: The message id if the message was successfully sent to that
+   *       recipient. Zero means message was not sent to that recipient.
+   *   - error_code: The error code number for a specific message.
    *   - error_message: The description of the error message.
    *   - gateway_error_code: The original error code from the sms gateway.
    *   - gateway_error_message: The original error message from the sms gateway.
@@ -89,8 +90,9 @@ interface MessageResultInterface {
    * @param string $recipient
    *   The number of the recipient for which the report is to be retrieved.
    * @return array
-   *   An array containing the message report @link see MessageResultInterface::getReport()
-   * @endlink
+   *   An array containing the message report
+   *   @link see SmsMessageResultInterface::getReport() @endlink
    */
   public function getReportFor($recipient);
-}
\ No newline at end of file
+
+}
diff --git a/src/Plugin/Gateway/DebugGateway.php b/src/Plugin/Gateway/DebugGateway.php
deleted file mode 100644
index 238a119..0000000
--- a/src/Plugin/Gateway/DebugGateway.php
+++ /dev/null
@@ -1,219 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\sms\Plugin\Gateway\DebugGatewayDefaultImpl
- */
-
-namespace Drupal\sms\Plugin\Gateway;
-
-use Drupal\sms\Gateway\GatewayDefaultImpl;
-use Symfony\Component\HttpFoundation\Request;
-
-/**
- * @SmsGateway(
- *   id = "debug",
- *   label = @Translation("Debug Gateway"),
- *   configurable = TRUE,
- * )
- */
-class DebugGatewayDefaultImpl extends GatewayDefaultImpl {
-  /**
-   * {@inheritdoc}
-   */
-  public function defaultConfiguration() {
-    return array(
-      'random' => '',
-      'message_failure' => '',
-      'delivery_failure' => '',
-      'retain_dlrs' => '',
-    ) + parent::defaultConfiguration();
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function getError() {
-    // TODO: Implement getError() method.
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  protected function doCommand($command, array $data, array $options = NULL) {
-    $config = $this->getConfiguration();
-    switch ($command) {
-      case 'send':
-        // Log the messages and generate message id's for each sender
-        $report = array();
-        $msgids = '';
-        foreach ($data['recipients'] as $number) {
-          // Coin toss to determine if message 'fails' or 'succeeds'
-          if (rand(0, 100) < $config['message_failure']) { // 'Failed'
-            $err = rand(-13, -1); // Random error message
-            $msgids .= $err . "\n";
-            $report[$number] = array(
-              'status' => FALSE,
-              'message_id' => '',
-              'error_code' => $err,
-              'error_message' => self::$errorCodes[$err],
-            );
-          }
-          else {    // 'Succeeded'
-            $msgid = $this->randomID();
-            $msgids .= $msgid . "\n";
-            $report[$number] = array(
-              'status' => TRUE,
-              'message_id' => $msgid,
-              'error_code' => 0,
-              'error_message' => '',
-            );
-          }
-        }
-        $message = $this->cleanMessage($data['message']);
-        $numbers = implode(',', $data['numbers']);
-        watchdog('sms_debug', "SMS message sent to %number with the text: @message\nmessage ids: @msgids", array('%number' => $numbers, '@message' => $data['message'], '@msgids' => $msgids), WATCHDOG_INFO);
-
-        // Save the msgids for dlr generation
-        $delivery_report = \Drupal::config('sms.debug_gateway.reports')->get('delivery_report');
-        $delivery_report[] = $report;
-        // @todo Optimize this later
-        \Drupal::config('sms.debug_gateway.reports')->set('delivery_report', $delivery_report)->save();
-        return array('status' => TRUE, 'report' => $report);
-
-      case 'report': 	// Delivery report
-        $dlr_config = \Drupal::config('sms.debug_gateway.reports');
-        $reports = array(
-          'status' => TRUE,
-          'data' => $dlr_config->get('delivery_report'),
-        );
-        if (!$config['retain_dlrs']) {
-          $dlr_config->delete('delivery_report')->save();
-        }
-        return $reports;
-
-      case 'credits': case 'test':
-      return array(
-        'status' => TRUE,
-        'credit_balance' => '100000'
-      );
-
-      default:
-        return array(
-          'status' => FALSE,
-          'message' => t('An error occurred during the HTTP request: @error', array('@error' => 'Unknown error'))
-        );
-    }
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function deliveryReport(Request $request) {
-    return;
-  }
-  
-  /**
-   * {@inheritdoc}
-   */
-  public function buildConfigurationForm(array $form, array &$form_state) {
-    $form['balance'] = array(
-      '#type' => 'item',
-      '#title' => t('Current balance'),
-      '#markup' => $this->balance(),
-    );
-    
-    $config = $this->getConfiguration() + array(
-        'random' => '',
-        'message_failure' => '',
-        'delivery_failure' => '',
-        'retain_dlrs' => '',
-      );
-
-    $form['debug'] = array(
-      '#type' => 'fieldset',
-      '#title' => t('Random failure settings'),
-      '#collapsible' => FALSE,
-      '#tree' => TRUE,
-    );
-    $form['debug']['random'] = array(
-      '#type' => 'checkbox',
-      '#title' => t('Enable random failures'),
-      '#description' => t('Enable generation of random errors to simulate real world messaging.'),
-      '#default_value' => $config['random'],
-    );
-    $form['debug']['message_failure'] = array(
-      '#type' => 'textfield',
-      '#title' => t('Message failure rate'),
-      '#description' => t('Simulated rate for failure of messages (percentage).'),
-      '#field_suffix' => '%',
-      '#size' => 30,
-      '#maxlength' => 64,
-      '#default_value' => $config['message_failure'],
-    );
-    $form['debug']['delivery_failure'] = array(
-      '#type' => 'textfield',
-      '#title' => t('Message delivery failure rate'),
-      '#description' => t('Simulated rate for failure of delivery reports (percentage).'),
-      '#field_suffix' => '%',
-      '#size' => 30,
-      '#maxlength' => 64,
-      '#default_value' => $config['delivery_failure'],
-    );
-
-    $form['retain_dlrs'] = array(
-      '#type' => 'checkbox',
-      '#title' => t('Retain delivery reports after poll'),
-      '#description' => t('Retains delivery reports after they have been polled. <br/>Default behaviour is to delete'),
-      '#default_value' => $config['retain_dlrs'],
-    );
-
-    $form['clear_dlrs'] = array(
-      '#type' => 'checkbox',
-      '#title' => t('Clear all delivery reports now'),
-      '#description' => t('Clear all delivery reports and records stored'),
-    );
-
-    return $form;
-  }
-  
-  /**
-   * {@inheritdoc}
-   */
-  public function validateConfigurationForm(array &$form, array &$form_state) {
-    if (!$this->test($form_state['values']['debug'])) {
-      $error = $this->getError();
-      form_set_error('', t('A Debug gateway error occurred: @error.', array('@error' => $error['description'])));
-    }
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function submitConfigurationForm(array &$form, array &$form_state) {
-    $this->configuration = $form_state['values']['debug'];
-    $this->configuration['retain_dlrs'] = $form_state['values']['retain_dlrs'];
-
-    // @todo: Storage for this should be moved to a more appropriate location.
-    if ($form_state['values']['clear_dlrs']) $this->configuration['debug_reports'] = array();
-  }
-
-  /**
-   * Debug error codes
-   */
-  static $errorCodes = array(
-    '-1' => 'SEND_ERROR',
-    '-2' => 'NOT_ENOUGHCREDITS',
-    '-3' => 'NETWORK_NOTCOVERED',
-    '-4' => 'SOCKET_EXCEPTION',
-    '-5' => 'INVALID_USER_OR_PASS',
-    '-6' => 'MISSING_DESTINATION_ADDRESS',
-    '-7' => 'MISSING_SMSTEXT',
-    '-8' => 'MISSING_SENDERNAME',
-    '-9' => 'DESTADDR_INVALIDFORMAT',
-    '-10' => 'MISSING_USERNAME',
-    '-11' => 'MISSING_PASS',
-    '-12' => 'MISSING_WAPURL',
-    '-13' => 'INVALID_DESTINATION_ADDRESS',
-  );
-}
diff --git a/src/Plugin/Gateway/LogGateway.php b/src/Plugin/Gateway/LogGateway.php
index c37c1f4..a3a8309 100644
--- a/src/Plugin/Gateway/LogGateway.php
+++ b/src/Plugin/Gateway/LogGateway.php
@@ -7,9 +7,7 @@
 namespace Drupal\sms\Plugin\Gateway;
 
 use Drupal\sms\Gateway\GatewayBase;
-use Drupal\sms\Message\Message;
-use Drupal\sms\Message\MessageInterface;
-use Drupal\sms\SmsMessage;
+use Drupal\sms\Message\SmsMessageInterface;
 use Symfony\Component\HttpFoundation\Request;
 
 /**
@@ -20,14 +18,15 @@ use Symfony\Component\HttpFoundation\Request;
  * )
  */
 class LogGateway extends GatewayBase {
+
   /**
    * {@inheritdoc}
    *
    * Log sms message to drupal watchdog().
    */
-  public function send(MessageInterface $sms, array $options) {
-    watchdog('sms', 'SMS message sent to %number with the text: @message',
-      array('%number' => implode(', ', $sms->getRecipients()), '@message' => $sms->getMessage()), WATCHDOG_INFO);
+  public function send(SmsMessageInterface $sms, array $options) {
+    $this->logger()->notice('SMS message sent to %number with the text: @message',
+      array('%number' => implode(', ', $sms->getRecipients()), '@message' => $sms->getMessage()));
 //    return array('status' => TRUE);
   }
 
@@ -52,4 +51,5 @@ class LogGateway extends GatewayBase {
   public function getError() {
     return array();
   }
+
 }
diff --git a/src/Sms.php b/src/Provider/DefaultSmsProvider.php
similarity index 51%
rename from src/Sms.php
rename to src/Provider/DefaultSmsProvider.php
index b4c4d9d..17961c6 100644
--- a/src/Sms.php
+++ b/src/Provider/DefaultSmsProvider.php
@@ -1,22 +1,24 @@
 <?php
+
 /**
  * @file
- * Contains \Drupal\sms\Sms
+ * Contains \Drupal\sms\Provider\DefaultSmsProvider
  */
 
-namespace Drupal\sms;
+namespace Drupal\sms\Provider;
 
 use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\sms\Gateway\GatewayInterface;
 use Drupal\sms\Gateway\GatewayManagerInterface;
-use Drupal\sms\Message\MessageInterface;
+use Drupal\sms\Message\SmsMessageInterface;
+use Drupal\sms\Message\SmsMessageResultInterface;
 use Drupal\sms\SmsException;
-use Drupal\sms\Message\Message;
 
 /**
- * This is the SMS service that provides messaging functionality
+ * The SMS provider that provides default messaging functionality.
  */
-class Sms implements SmsProviderInterface {
+class DefaultSmsProvider implements SmsProviderInterface {
+
   /**
    * @var \Drupal\sms\Gateway\GatewayManager
    *
@@ -50,14 +52,17 @@ class Sms implements SmsProviderInterface {
    * @TODO An effective method of cascading messages and errors back up from the
    *   gateways.
    */
-  public function send(MessageInterface $sms, array $options = array()) {
-    $gateway = $this->gatewayManager->getDefaultGateway();
+  public function send(SmsMessageInterface $sms, array $options = array()) {
+    // Check if preferred gateway is specified in the $options.
+    if (isset($options['gateway'])) {
+      $gateway = $this->gatewayManager->getGateway($options['gateway']);
+    }
+    if (empty($gateway)) {
+      $gateway = $this->gatewayManager->getDefaultGateway();
+    }
 
     if ($this->preProcess($sms, $options, $gateway)) {
-      $response = NULL;
-      $response = $gateway->send($sms, $options);
-      $result = $this->handleResult($response, $sms);
-
+      $result = $this->process($sms, $options, $gateway);
       $this->postProcess($sms, $options, $gateway, $result);
       return $result;
     }
@@ -67,32 +72,40 @@ class Sms implements SmsProviderInterface {
   }
 
   /**
+   * Processes the sms message and handles the response from the gateway.
+   */
+  protected function process(SmsMessageInterface $sms, array $options, GatewayInterface $gateway) {
+    $this->moduleHandler->invokeAll('sms_send', [$sms, $options, $gateway]);
+    // @todo Apply token replacements.
+    $response = $gateway->send($sms, $options);
+    $result = $this->handleResult($response, $sms);
+    return $result;
+  }
+
+  /**
    * Calls pre-process hooks and ensures that the action is still permitted.
    *
-   * @param \Drupal\sms\Message\MessageInterface $sms
+   * @param \Drupal\sms\Message\SmsMessageInterface $sms
    *   The sms to be sent.
    * @param array $options
    *   Additonal options to be passed to the sms gateway.
    * @param \Drupal\sms\Gateway\GatewayInterface $gateway
        The default gateway for sending this message.
+   *
    * @returns bool
    *   Whether to continue sending or not.
    */
-  protected function preProcess(MessageInterface $sms, array $options, GatewayInterface $gateway) {
-    // Call the send hook.
-    // @todo change this later to a preprocess or presend hook
-    $continue = TRUE;
-    foreach ($this->moduleHandler->getImplementations('sms_send') as $module) {
-      $function = $module . '_sms_send';
-      $continue &= $function($sms, $options, $gateway);
-    }
-    return $continue;
+  protected function preProcess(SmsMessageInterface $sms, array $options, GatewayInterface $gateway) {
+    // Call the send pre process hooks.
+    $return = $this->moduleHandler->invokeAll('sms_send_process', ['pre process', $sms, $options, $gateway]);
+    // Return FALSE if any of the hooks returned FALSE.
+    return !in_array(FALSE, $return);
   }
 
   /**
    * Calls post process hooks.
    *
-   * @param \Drupal\sms\Message\MessageInterface $sms
+   * @param \Drupal\sms\Message\SmsMessageInterface $sms
    *   The sms that was sent.
    * @param array $options
    *   Additonal options that were passed to the sms gateway.
@@ -101,12 +114,9 @@ class Sms implements SmsProviderInterface {
    * @param bool $result
    *   Whether the sms sending was successful or not.
    */
-  protected function postProcess(MessageInterface $sms, array $options, GatewayInterface $gateway, $result) {
-    // Post process hook
-    foreach ($this->moduleHandler->getImplementations('sms_send_process') as $module) {
-      $function = $module . '_sms_send_process';
-      $function('post process', $sms, $options, $gateway, $result);
-    }
+  protected function postProcess(SmsMessageInterface $sms, array $options, GatewayInterface $gateway, $result) {
+    // Call the send post process hooks.
+    $this->moduleHandler->invokeAll('sms_send_process', ['post process', $sms, $options, $gateway]);
   }
 
   /**
@@ -114,7 +124,7 @@ class Sms implements SmsProviderInterface {
    *
    * @param array
    *   The result to be handled.
-   * @param \Drupal\sms\Message\MessageInterface
+   * @param \Drupal\sms\Message\SmsMessageInterface
    *   The message that was sent.
    * @return bool
    *   True if message was sent successfully. Throws an SmsException if message
@@ -122,25 +132,18 @@ class Sms implements SmsProviderInterface {
    * @throws \Drupal\sms\SmsException
    *
    */
-  protected function handleResult($result, MessageInterface $sms) {
-    if ($result['status']) {
+  protected function handleResult(SmsMessageResultInterface $result, SmsMessageInterface $sms) {
+    if ($result->getStatus()) {
       return TRUE;
     }
     else {
       // @todo Review all of this.
-      $variables['%number'] = implode(',', $sms->getRecipients());
-      if (!empty($result['variables'])) {
-        $variables = array_merge($variables, $result['variables']);
-      }
-      if ($result['message']) {
-        $variables['%message'] = $result['message'];
-        $error_message = t('Sending SMS to %number failed. The gateway said: %message', $variables);
-      }
-      else {
-        $error_message = t('Sending SMS to %number failed.', $variables);
+      $error_message = t('Sending SMS to %number failed.', ['%number' => implode(',', $sms->getRecipients())]);
+      if ($message = $result->getErrorMessage()) {
+        $error_message .= t(' The gateway said %message.', ['%message' => $message]);
       }
+      \Drupal::logger('sms')->error($message);
       throw new SmsException($error_message);
-//      watchdog('sms', $error_message, $variables, WATCHDOG_ERROR);
 //      return FALSE;
     }
   }
@@ -148,8 +151,15 @@ class Sms implements SmsProviderInterface {
   /**
    * {@inheritdoc}
    */
-  public function incoming(MessageInterface $message, array $options) {
-
+  public function incoming(SmsMessageInterface $message, array $options) {
+//    if (module_exists('rules')) {
+//      $options += array('number' => $number, 'message' => $message);
+//      rules_invoke_event('sms_incoming', $options);
+//    }
+    // Execute three phases
+    $this->moduleHandler->invokeAll('sms_incoming', array('pre process', $message, $options));
+    $this->moduleHandler->invokeAll('sms_incoming', array('process', $message, $options));
+    $this->moduleHandler->invokeAll('sms_incoming', array('post process', $message, $options));
   }
 
   /**
@@ -162,4 +172,4 @@ class Sms implements SmsProviderInterface {
     $this->moduleHandler->invokeAll('sms_receipt', array('post process', $number, $reference, $message_status, $options));
   }
 
-}
\ No newline at end of file
+}
diff --git a/src/SmsProviderInterface.php b/src/Provider/SmsProviderInterface.php
similarity index 52%
rename from src/SmsProviderInterface.php
rename to src/Provider/SmsProviderInterface.php
index 646bda1..76b3bfc 100644
--- a/src/SmsProviderInterface.php
+++ b/src/Provider/SmsProviderInterface.php
@@ -1,60 +1,62 @@
 <?php
+
 /**
  * @file
  * Contains definition of \Drupal\sms\SmsProviderInterface
  */
 
-namespace Drupal\sms;
-use Drupal\sms\Message\Message;
-use Drupal\sms\Message\MessageInterface;
+namespace Drupal\sms\Provider;
+
+use Drupal\sms\Gateway\GatewayInterface;
+use Drupal\sms\Message\SmsMessageInterface;
 
 /**
  * Provides an interface for sending messages
  */
 interface SmsProviderInterface {
+
   /**
    * Sends an sms using the active gateway.
    *
-   * @param \Drupal\sms\Message\MessageInterface
-   *   The sms to be sent.
+   * @param \Drupal\sms\Message\SmsMessageInterface
+   *   The message to be sent.
    * @param array
-   *   Additonal options to be passed to the sms gateway.
+   *   Additional options to be passed to the sms gateway.
    */
-  public function send(MessageInterface $sms, array $options);
+  public function send(SmsMessageInterface $sms, array $options);
 
   /**
    * Handles a message received by the server.
    *
-   * @param \Drupal\sms\Message\MessageInterface
+   * @param \Drupal\sms\Message\SmsMessageInterface
    *   The message received.
    * @param array
    *   Additional options to be passed to the sms gateway.
    */
-  public function incoming(MessageInterface $sms, array $options);
+  public function incoming(SmsMessageInterface $sms, array $options);
 
   /**
-   * Handles responses to .
+   * Handles responses to the sms provider from gateways.
    *
    * Allows gateway modules to pass message receipts in a standard format for
-   * processing, and provides a basic set of status codes for common code handling.
+   * processing and provides basic set of status codes for common code handling.
    *
    * Allowed message status codes are defined as constants at
-   * {@link} \Drupal\sms\Gateway\GatewayInterface
+   * @link \Drupal\sms\Gateway\GatewayInterface @endlink
    *
    * The gateway code and string will often be provided in the $options array as
    * 'gateway_message_status' and 'gateway_message_status_text'.
    *
    * @param string $number
    *   The sender's mobile number.
-   *
    * @param string $reference
    *   Unique message reference code, as provided when message is sent.
-   *
    * @param int $message_status
-   *   An SMS Framework message status code, as per the defined constants.
-   *
+   *   (optional) An SMS Framework message status code, per the defined constants.
+   *    Defaults to \Drupal\sms\Gateway\GatewayInterface::STATUS_UNKNOWN.
    * @param array $options
-   *   Extended options passed by the receipt receiver.
+   *   (optional) Extended options passed by the receipt receiver.
    */
-  public function receipt($number, $reference, $message_status = SMS_GW_UNKNOWN_STATUS, $options = array());
-} 
\ No newline at end of file
+  public function receipt($number, $reference, $message_status = GatewayInterface::STATUS_UNKNOWN, $options = array());
+
+}
diff --git a/src/Tests/SmsFrameworkWebTest.php b/src/Tests/SmsFrameworkWebTest.php
index 9f5e772..1d7fdc6 100644
--- a/src/Tests/SmsFrameworkWebTest.php
+++ b/src/Tests/SmsFrameworkWebTest.php
@@ -22,7 +22,11 @@ class SmsFrameworkWebTest extends WebTestBase {
    * Tests that the correct gateways list is obtained.
    */
   public function testGatewaysList() {
-    $this->assertEqual(array('log' => t('Log only'), 'test' => t('For testing')), sms_gateways('names'));
+    $test_gateways = [
+      'log' => 'Log only',
+      'test' => 'For testing',
+    ];
+    $this->assertEqual($test_gateways, sms_gateways('names'));
   }
 
   /**
@@ -31,20 +35,21 @@ class SmsFrameworkWebTest extends WebTestBase {
   public function testDefaultGateway() {
     // Test initial default gateway.
     $gw = sms_default_gateway();
-    $this->assertEqual($gw['identifier'], 'log', 'Initial default gateway is "log".');
+    $this->assertEqual($gw->getIdentifier(), 'log', 'Initial default gateway is "log".');
 
     $this->drupalLogin($this->drupalCreateUser(['administer smsframework']));
     // Set up default log gateway.
-    $this->drupalPostForm('admin/config/smsframework/gateways', ['default' => 'log'], t('Set default gateway'));
+    $this->drupalPostForm('admin/config/smsframework/gateways', ['default' => 'log'], 'Save settings');
     $this->assertResponse(200);
     $gw = sms_default_gateway();
-    $this->assertEqual($gw['identifier'], 'log', 'Default gateway set to log.');
+    $this->assertEqual($gw->getIdentifier(), 'log', 'Default gateway set to log.');
 
     // Set up default test gateway.
-    $this->drupalPostForm('admin/config/smsframework/gateways', ['default' => 'test'], t('Set default gateway'));
+    $this->drupalPostForm('admin/config/smsframework/gateways', ['default' => 'test'], 'Save settings');
     $this->assertResponse(200);
+    $this->rebuildContainer();
     $gw = sms_default_gateway();
-    $this->assertEqual($gw['identifier'], 'test', 'Default gateway set to test.');
+    $this->assertEqual($gw->getIdentifier(), 'test', 'Default gateway set to test.');
   }
 
   /**
@@ -59,10 +64,12 @@ class SmsFrameworkWebTest extends WebTestBase {
       'method' => 0,
       'ssl' => false,
     );
-    $this->drupalPostForm('admin/config/smsframework/gateways/test', $edit, t('Save'));
+    $this->drupalPostForm('admin/config/smsframework/gateways/test', $edit, 'Save configuration');
     $this->assertResponse(200);
+    $this->rebuildContainer();
     $gateway = sms_gateways('gateway', 'test');
-    $this->assertEqual($edit, $gateway['configuration'], 'SMS Test gateway successfully configured.');
+//    $this->assertEqual($edit, $gateway->getConfiguration(), 'SMS Test gateway successfully configured.');
+    $this->assertEqual($edit, $gateway->getConfiguration()['custom']);
   }
 
   /**
diff --git a/tests/modules/sms_test_gateway/sms_test_gateway.module b/tests/modules/sms_test_gateway/sms_test_gateway.module
index ad85da1..1d527a8 100644
--- a/tests/modules/sms_test_gateway/sms_test_gateway.module
+++ b/tests/modules/sms_test_gateway/sms_test_gateway.module
@@ -4,6 +4,7 @@
  * @file
  * A test gateway to be used for testing the sms framework
  */
+use Drupal\sms\Message\SmsMessageInterface;
 
 /**
  * Implements hook_gateway_info().
@@ -23,18 +24,32 @@ function sms_test_gateway_gateway_info() {
 }
 
 /**
- * Send callback
+ * Send callback.
+ *
+ * @param \Drupal\sms\Message\SmsMessageInterface $sms
+ *   The message to be sent
+ * @param array $options
+ *   Options for sending the message.
+ *
+ * @return array
  */
-function sms_test_gateway_send($number = NULL, $message = NULL, $options = array()) {
+function sms_test_gateway_send(SmsMessageInterface $sms, $options = array()) {
   $result = &drupal_static('sms_test_gateway_result');
 
-  if (!is_null($number) && !is_null($message)) {
-    $result['number'] = $number;
-    $result['message'] = $message;
+  if (!is_null($sms->getRecipients()) && !is_null($sms->getMessage())) {
+    $result['number'] = implode(',',$sms->getRecipients());
+    $result['message'] = $sms->getMessage();
     $result['options'] = $options;
     \Drupal::state()->set('sms_test_gateway_result', $result);
   }
-  return array('status' => TRUE, 'result' => $result);
+  return [
+    'status' => TRUE,
+    'result' => $result,
+    'credit_balance' => 1000,
+    'credit_used' => count($sms->getRecipients()),
+    'error_message' => '',
+    'report' => $result,
+  ];
 }
 
 function sms_test_gateway_result($reset = FALSE) {
@@ -144,23 +159,25 @@ function sms_test_gateway_config_form($configuration) {
  * less than 10 digits, or has non-numeric characters or has country code 990,
  * 997 or 999.
  *
- * @param string $number
- *   The number to be validated.
+ * @param array $numbers
+ *   The numbers to be validated.
  *
  * @return array
  *   List of errors.
  */
-function sms_test_gateway_validate_number($number) {
-  $code = substr($number, 0, 3);
+function sms_test_gateway_validate_number($numbers) {
   $errors = array();
-  if (preg_match('/[^0-9]/', $number)) {
-    $errors[] = t('Non-numeric character found in number.');
-  }
-  if (strlen($number) > 15 || strlen($number) < 10) {
-    $errors[] = t('Number longer than 15 digits or shorter than 10 digits.');
-  }
-  if ($code == '990' || $code == '997' || $code == '999') {
-    $errors[] = t('Country code not allowed');
+  foreach ($numbers as $number) {
+    $code = substr($number, 0, 3);
+    if (preg_match('/[^0-9]/', $number)) {
+      $errors[] = t('Non-numeric character found in number.');
+    }
+    if (strlen($number) > 15 || strlen($number) < 10) {
+      $errors[] = t('Number longer than 15 digits or shorter than 10 digits.');
+    }
+    if ($code == '990' || $code == '997' || $code == '999') {
+      $errors[] = t('Country code not allowed');
+    }
   }
   return $errors;
 }