diff --git a/modules/sms_blast/src/Tests/SmsBlastWebTest.php b/modules/sms_blast/src/Tests/SmsBlastWebTest.php
index b4df3b1..ee48f26 100644
--- a/modules/sms_blast/src/Tests/SmsBlastWebTest.php
+++ b/modules/sms_blast/src/Tests/SmsBlastWebTest.php
@@ -7,23 +7,23 @@
 
 namespace Drupal\sms_blast\Tests;
 
-use \Drupal\simpletest\WebTestBase;
+use Drupal\sms\Tests\SmsFrameworkWebTestBase;
 
 /**
  * Integration tests for the sms_blast module.
  *
  * @group SMS Framework
  */
-class SmsBlastWebTest extends WebTestBase {
+class SmsBlastWebTest extends SmsFrameworkWebTestBase {
 
-  public static $modules = ['sms', 'sms_test_gateway', 'sms_user', 'sms_blast'];
+  public static $modules = ['sms_user', 'sms_blast'];
 
   /**
    * Tests sending sms blast.
    */
   function testSendBlast() {
     // Set up test default gateway and test user.
-    $this->container->get('config.factory')->getEditable('sms.settings')->set('default_gateway', 'test')->save();
+    $this->setDefaultGateway('test');
     $user = $this->drupalCreateUser(array('receive sms', 'Send SMS Blast'));
     $this->drupalLogin($user);
     $data = array(
diff --git a/modules/sms_devel/src/Tests/SmsDevelWebTest.php b/modules/sms_devel/src/Tests/SmsDevelWebTest.php
index acd6567..081b64b 100644
--- a/modules/sms_devel/src/Tests/SmsDevelWebTest.php
+++ b/modules/sms_devel/src/Tests/SmsDevelWebTest.php
@@ -7,16 +7,16 @@
 
 namespace Drupal\sms_devel\Tests;
 
-use Drupal\simpletest\WebTestBase;
+use Drupal\sms\Tests\SmsFrameworkWebTestBase;
 
 /**
  * Tests the send/receive form provided by SMS Devel.
  *
  * @group SMS Framework
  */
-class SmsDevelWebTest extends WebTestBase {
+class SmsDevelWebTest extends SmsFrameworkWebTestBase {
 
-  public static $modules = ['sms', 'sms_test_gateway', 'sms_devel'];
+  public static $modules = ['sms_devel'];
 
   /**
    * Tests if messages sent using the test send form are stored properly.
@@ -28,7 +28,7 @@ class SmsDevelWebTest extends WebTestBase {
     $this->drupalLogin($user);
 
     // Set up test default gateway.
-    $this->config('sms.settings')->set('default_gateway', 'test')->save();
+    $this->setDefaultGateway('test');
 
     $test_message1 = array(
       'number' => '1234567890',
diff --git a/modules/sms_user/src/Tests/SmsUserWebTest.php b/modules/sms_user/src/Tests/SmsUserWebTest.php
index 3b7b20f..380c54c 100644
--- a/modules/sms_user/src/Tests/SmsUserWebTest.php
+++ b/modules/sms_user/src/Tests/SmsUserWebTest.php
@@ -7,7 +7,7 @@
 
 namespace Drupal\sms_user\Tests;
 
-use Drupal\simpletest\WebTestBase;
+use Drupal\sms\Tests\SmsFrameworkWebTestBase;
 use Drupal\user\Entity\User;
 
 /**
@@ -18,19 +18,16 @@ use Drupal\user\Entity\User;
  * @todo Add tests for creation of users via sms.
  * @todo Add tests for integration with rules and actions modules.
  */
-class SmsUserWebTest extends WebTestBase {
+class SmsUserWebTest extends SmsFrameworkWebTestBase {
 
-  public static $modules = ['sms', 'sms_test_gateway', 'sms_user', 'syslog', 'sms_devel'];
+  public static $modules = ['sms_user', 'syslog', 'sms_devel'];
 
   /**
    * Tests user adding phone number.
    */
   public function testNumberConfirmationAndSmsUserSend() {
     // Set up test default gateway.
-    /** @var \Drupal\sms\Gateway\GatewayManagerInterface $gateway_manager */
-    $gateway_manager = $this->container->get('plugin.manager.sms_gateway');
-    $gateway_manager->setEnabledGateways(['test']);
-    $gateway_manager->setDefaultGateway('test');
+    $this->setDefaultGateway('test');
     $user = $this->drupalCreateUser(array('receive sms', 'edit own sms number'));
     $this->drupalLogin($user);
 
@@ -161,8 +158,7 @@ class SmsUserWebTest extends WebTestBase {
     $this->drupalLogin($excluded_user);
 
     // Set up test default gateway.
-    $this->config('sms.settings')->set('default_gateway', 'test')->save();
-
+    $this->setDefaultGateway('test');
     $sms_user_settings = array(
       'registration_enabled' => TRUE,
       'allow_password' => TRUE,
diff --git a/src/Gateway/GatewayBase.php b/src/Gateway/GatewayBase.php
index 428caa6..2a64c4d 100644
--- a/src/Gateway/GatewayBase.php
+++ b/src/Gateway/GatewayBase.php
@@ -35,8 +35,7 @@ abstract class GatewayBase extends PluginBase implements GatewayInterface {
    */
   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'] = [];
+    $this->configuration = array_merge($this->defaultConfiguration(), $this->configuration);
   }
 
   /**
@@ -97,10 +96,7 @@ abstract class GatewayBase extends PluginBase implements GatewayInterface {
       'name' => $this->pluginDefinition['id'],
       'label' => (string) $this->pluginDefinition['label'],
       'enabled' => FALSE,
-      'custom' => [
-        'use_ssl' => FALSE,
-        'send_method' => 'HTTP_POST',
-      ]
+      'custom' => [],
     ];
   }
 
@@ -136,7 +132,7 @@ abstract class GatewayBase extends PluginBase implements GatewayInterface {
    * {@inheritdoc}
    */
   public function sendForm(array &$form, FormStateInterface $form_state) {
-    return array();
+    return [];
   }
 
   /**
@@ -163,7 +159,7 @@ abstract class GatewayBase extends PluginBase implements GatewayInterface {
   /**
    * {@inheritdoc}
    */
-  public function validateNumbers(array $numbers, array $options = array()) {
+  public function validateNumbers(array $numbers, array $options = []) {
     return [];
   }
 
@@ -185,7 +181,7 @@ abstract class GatewayBase extends PluginBase implements GatewayInterface {
    * {@inheritdoc}
    */
   public function getError() {
-    return array();
+    return [];
   }
 
   /**
diff --git a/src/Gateway/GatewayManager.php b/src/Gateway/GatewayManager.php
index 63ea7ee..95beef9 100644
--- a/src/Gateway/GatewayManager.php
+++ b/src/Gateway/GatewayManager.php
@@ -11,6 +11,7 @@ use Drupal\Core\Cache\CacheBackendInterface;
 use Drupal\Core\Config\ConfigFactory;
 use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\Core\Plugin\DefaultPluginManager;
+use Drupal\Core\StringTranslation\TranslationWrapper;
 
 /**
  * Manages SMS gateways implemented using AnnotatedClassDiscovery
@@ -65,8 +66,11 @@ class GatewayManager extends DefaultPluginManager implements GatewayManagerInter
     $this->defaultGateway = $this->config->get('sms.settings')->get('default_gateway');
   }
 
+  /**
+   * {@inheritdoc}
+   */
   public function getGatewayPlugins() {
-    return $this->discovery->getDefinitions();
+    return $this->getDefinitions();
   }
 
   /**
@@ -133,11 +137,13 @@ class GatewayManager extends DefaultPluginManager implements GatewayManagerInter
    * {@inheritdoc}
    */
   public function setEnabledGateways(array $gateway_ids) {
+    $gateways = [];
     foreach ($gateway_ids as $gateway_id) {
       $gateway = $this->getGateway($gateway_id);
       $gateway->setEnabled(TRUE);
-      $this->saveGateway($gateway);
+      $gateways[] = $gateway;
     }
+    $this->saveGateways($gateways);
   }
 
   /**
@@ -151,15 +157,35 @@ class GatewayManager extends DefaultPluginManager implements GatewayManagerInter
    * {@inheritdoc}
    */
   public function saveGateway(GatewayInterface $gateway) {
-    $this->config->getEditable('sms.gateway.config')
-      ->set($gateway->getName(), $gateway->getConfiguration())
-      ->save();
+    $this->saveGateways([$gateway]);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function saveGateways(array $gateways) {
+    $config = $this->config->getEditable('sms.gateway.config');
+    /** @var \Drupal\sms\Gateway\GatewayInterface $gateway */
+    foreach ($gateways as $gateway) {
+      $config->set($gateway->getName(), $gateway->getConfiguration());
+    }
+    $config->save();
+    // @todo Implement more granular cache invalidations.
+    // Clear static caches.
+    $this->gateways = NULL;
+    $this->names = NULL;
+    // Clear dynamic caches.
+    $this->clearCachedDefinitions();
   }
 
   /**
    * {@inheritdoc}
    */
   public function addGateway($plugin_id, array $configuration) {
+    // Initialize existing gateways first.
+    if (!isset($this->gateways)) {
+      $this->buildGateways();
+    }
     $name = $configuration['name'];
     if (!isset($configuration['name'])) {
       throw new \InvalidArgumentException('A machine name is required to create an SMS gateway.');
@@ -175,44 +201,43 @@ class GatewayManager extends DefaultPluginManager implements GatewayManagerInter
    *
    * @return array
    *   \Drupal\sms\Gateway\GatewayInterface[]
-   *
-   * @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();
-    $plugin_config = [];
-    foreach ($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 => $instance_config) {
       // Note that DefaultFactory::createInstance will get the right definitions.
       if (!isset($instance_config['plugin_id'])) {
-        throw new \InvalidArgumentException(sprintf('Gateway %s configured without a plugin id.', $id));
+        throw new \InvalidArgumentException(sprintf('Gateway "%s" configured without a plugin id.', $id));
       }
       $this->gateways[$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 = $this->moduleHandler->invokeAll('gateway_info');
-    $gateway_configs = $this->config->get('sms.gateway.config');
-    foreach ($gateway_array as $id => $info) {
-      $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();
+  /**
+   * {@inheritdoc}
+   *
+   * @todo remove BC-shim when all gateways are converted to plugins.
+   */
+  public function findDefinitions() {
+    // Get discovered plugin definitions.
+    $definitions = parent::findDefinitions();
+
+    // Add hook_gateway_info definitions.
+    foreach ($this->moduleHandler->invokeAll('gateway_info') as $id => $hook_info) {
+      // @todo This allows overwriting of annotated plugins by hook plugins.
+      // @todo Is that acceptable?
+      $definitions[$id] = [
+        'id' => $id,
+        'label' => new TranslationWrapper($hook_info['name']),
+        'configurable' => is_callable($hook_info['configure form']),
+        'class' => '\Drupal\sms\Gateway\HookGateway',
+        'provider' => 'sms',
+        'hook_info' => $hook_info,
+      ];
     }
+    return $definitions;
   }
 
 }
diff --git a/src/Gateway/GatewayManagerInterface.php b/src/Gateway/GatewayManagerInterface.php
index a127611..ca1443d 100644
--- a/src/Gateway/GatewayManagerInterface.php
+++ b/src/Gateway/GatewayManagerInterface.php
@@ -83,7 +83,7 @@ interface GatewayManagerInterface {
   public function addGateway($plugin_id, array $configuration);
 
   /**
-   * Saves the configuration of a gateway.
+   * Saves the configuration of a single gateway.
    *
    * @param \Drupal\sms\Gateway\GatewayInterface
    *   The gateway object whose configuration is to be saved.
@@ -91,6 +91,14 @@ interface GatewayManagerInterface {
   public function saveGateway(GatewayInterface $gateway);
 
   /**
+   * Saves the configuration of multiple gateways.
+   *
+   * @param \Drupal\sms\Gateway\GatewayInterface[]
+   *   An array of gateway objects whose configuration is to be saved.
+   */
+  public function saveGateways(array $gateway);
+
+  /**
    * Gets the list of gateway plugins discovered by this gateway manager.
    *
    * @return \Drupal\sms\Gateway\GatewayInterface[]
diff --git a/src/Gateway/HookGateway.php b/src/Gateway/HookGateway.php
index 9c7c134..ac0fbc3 100644
--- a/src/Gateway/HookGateway.php
+++ b/src/Gateway/HookGateway.php
@@ -18,25 +18,12 @@ use Symfony\Component\HttpFoundation\Request;
 class HookGateway extends GatewayBase {
 
   /**
-   * Constructs a new hook-based gateway.
-   *
-   * @param array $info
-   *   The info extracted from hook_gateway_info() for this gateway.
-   * @param array $configuration
-   *   The settings stored in config for this gateway.
-   */
-  public function __construct(array $info, array $configuration) {
-    $this->configuration = $configuration + ['custom' => []];
-    $this->pluginId = 'sms_hook_gateway';
-    $this->pluginDefinition = $info;
-  }
-
-  /**
    * {@inheritdoc}
    */
   public function send(SmsMessageInterface $sms, array $options) {
-    if (is_callable($this->pluginDefinition['send'])) {
-      $result = $this->pluginDefinition['send']($sms, $options);
+    $hook = $this->pluginDefinition['hook_info']['send'];
+    if (is_callable($hook)) {
+      $result = $hook($sms, $options);
       return new SmsMessageResult($result);
     }
     throw new \BadMethodCallException(sprintf('No send method defined for gateway %s', $this->configuration['name']));
@@ -46,8 +33,9 @@ class HookGateway extends GatewayBase {
    * {@inheritdoc}
    */
   public function balance() {
-    if (is_callable($this->pluginDefinition['balance'])) {
-      return $this->pluginDefinition['balance']();
+    $hook = $this->pluginDefinition['hook_info']['balance'];
+    if (is_callable($hook)) {
+      return $hook();
     }
     return 0;
   }
@@ -56,47 +44,19 @@ class HookGateway extends GatewayBase {
    * {@inheritdoc}
    */
   public function deliveryReport(Request $request) {
-    if (is_callable($this->pluginDefinition['delivery report'])) {
-      return $this->pluginDefinition['delivery report']();
+    $hook = $this->pluginDefinition['hook_info']['delivery report'];
+    if (is_callable($hook)) {
+      return $hook();
     }
   }
 
   /**
-   * Gets the machine  name of the gateway.
-   *
-   * @return string
-   */
-  public function getIdentifier() {
-    return $this->pluginDefinition['identifier'];
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function getName() {
-    return $this->pluginDefinition['identifier'];
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function getLabel() {
-    return $this->pluginDefinition['name'];
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function isConfigurable() {
-    return isset($this->pluginDefinition['configure form']) && is_callable($this->pluginDefinition['configure form']);
-  }
-
-  /**
    * {@inheritdoc}
    */
   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()));
+    $hook = $this->pluginDefinition['hook_info']['configure form'];
+    if (is_callable($hook)) {
+      return array_merge($form, $hook($this->getCustomConfiguration()));
     }
     else {
       throw new \RuntimeException($this->t('Configuration form callback not available.'));
@@ -107,18 +67,20 @@ class HookGateway extends GatewayBase {
    * {@inheritdoc}
    */
   public function validateConfigurationForm(array &$form, FormStateInterface $form_state) {
-    $function = $this->pluginDefinition['configure form'] . '_validate';
-    if (is_callable($function)) $function($form, $form_state);
+    $hook = $this->pluginDefinition['hook_info']['configure form'] . '_validate';
+    if (is_callable($hook)) {
+      $hook($form, $form_state);
+    }
   }
 
   /**
    * {@inheritdoc}
    */
   public function submitConfigurationForm(array &$form, FormStateInterface $form_state) {
-    $function = $this->pluginDefinition['configure form'] . '_submit';
-    if (is_callable($function)) {
+    $hook = $this->pluginDefinition['hook_info']['configure form'] . '_submit';
+    if (is_callable($hook)) {
       // Call the hook gateway submit callback.
-      $function($form, $form_state);
+      $hook($form, $form_state);
     }
     // Update the configuration.
     $this->setCustomConfiguration($form_state->getValues());
@@ -128,8 +90,9 @@ class HookGateway extends GatewayBase {
    * {@inheritdoc}
    */
   public function sendForm(array &$form, FormStateInterface $form_state) {
-    if (is_callable($this->pluginDefinition['send form'])) {
-      return $this->pluginDefinition['send form']($form, $form_state);
+    $hook = $this->pluginDefinition['hook_info']['send form'];
+    if (is_callable($hook)) {
+      return $hook($form, $form_state);
     }
     else {
       return array();
@@ -140,8 +103,9 @@ class HookGateway extends GatewayBase {
    * {@inheritdoc}
    */
   public function validateNumbers(array $numbers, array $options = array()) {
-    if (is_callable($this->pluginDefinition['validate number'])) {
-      return $this->pluginDefinition['validate number']($numbers, $options);
+    $hook = $this->pluginDefinition['hook_info']['validate number'];
+    if (is_callable($hook)) {
+      return $hook($numbers, $options);
     }
     else {
       return array();
diff --git a/src/Plugin/Gateway/LogGateway.php b/src/Plugin/Gateway/LogGateway.php
index 59e0a2a..f7cabfe 100644
--- a/src/Plugin/Gateway/LogGateway.php
+++ b/src/Plugin/Gateway/LogGateway.php
@@ -14,7 +14,7 @@ use Drupal\sms\Message\SmsMessageResult;
  * @SmsGateway(
  *   id = "log",
  *   label = @Translation("Log only"),
- *   configurable = FALSE,
+ *   configurable = false,
  * )
  */
 class LogGateway extends GatewayBase {
diff --git a/src/Tests/SmsFrameworkWebTest.php b/src/Tests/SmsFrameworkWebTest.php
index 4092b15..5467c75 100644
--- a/src/Tests/SmsFrameworkWebTest.php
+++ b/src/Tests/SmsFrameworkWebTest.php
@@ -7,16 +7,32 @@
 
 namespace Drupal\sms\Tests;
 
-use \Drupal\simpletest\WebTestBase;
-
 /**
  * Integration tests for the SMS Framework.
  *
  * @group SMS Framework
  */
-class SmsFrameworkWebTest extends WebTestBase {
-
-  public static $modules = ['sms', 'sms_test_gateway'];
+class SmsFrameworkWebTest extends SmsFrameworkWebTestBase {
+  
+  /**
+   * Tests the HookGateway implementation.
+   */
+  public function testHookGatewayIntegration() {
+    // Test that hook gateway plugins are correctly discovered.
+    $gateway_plugins = $this->gatewayManager->getGatewayPlugins();
+    $this->assertEqual(array_keys($gateway_plugins), ['log', 'test'], 'Hook-based gateway discovered.');
+    $this->assertEqual($gateway_plugins['test']['hook_info'], sms_test_gateway_gateway_info()['test'], 'sms_test_gateway hooks correct.');
+
+    // Confirm the existence of the test gateway.
+    $test_gateway = $this->gatewayManager->getGateway('test');
+    $this->assertNotNull($test_gateway, 'Test gateway not null');
+
+    // Add an instance and confirm that it exists
+    $this->gatewayManager->addGateway('test', ['name' => 'test_instance', 'label' => 'Test gateway instance']);
+    $test_gateway = $this->gatewayManager->getGateway('test_instance');
+    $this->assertEqual(get_class($test_gateway), 'Drupal\sms\Gateway\HookGateway');
+    $this->assertEqual($test_gateway->getLabel(), 'Test gateway instance');
+  }
 
   /**
    * Tests that the correct gateways list is obtained.
@@ -30,6 +46,20 @@ class SmsFrameworkWebTest extends WebTestBase {
   }
 
   /**
+   * Tests the add gateway functionality.
+   */
+  public function testAddGateways() {
+    $gateways = ['log', 'test'];
+    $this->assertEqual($gateways, array_keys($this->gatewayManager->getAvailableGateways()));
+    for ($i = 0; $i < 3; $i++) {
+      $name = $this->randomMachineName();
+      $this->gatewayManager->addGateway('test', ['name' => $name]);
+      $gateways[] = $name;
+      $this->assertEqual($gateways, array_keys($this->gatewayManager->getAvailableGateways()));
+    }
+  }
+
+  /**
    * Tests setting up the default gateway.
    */
   public function testDefaultGateway() {
@@ -47,7 +77,7 @@ class SmsFrameworkWebTest extends WebTestBase {
     // Set up default test gateway.
     $this->drupalPostForm('admin/config/smsframework/gateways', ['default' => 'test'], 'Save settings');
     $this->assertResponse(200);
-    $this->rebuildContainer();
+    $this->resetAll();
     $gw = sms_default_gateway();
     $this->assertEqual($gw->getIdentifier(), 'test', 'Default gateway set to test.');
   }
@@ -66,8 +96,7 @@ class SmsFrameworkWebTest extends WebTestBase {
     );
     $this->drupalPostForm('admin/config/smsframework/gateways/test', $edit, 'Save configuration');
     $this->assertResponse(200);
-    $this->rebuildContainer();
-    $gateway = sms_gateways('gateway', 'test');
+    $gateway = $this->gatewayManager->getGateway('test');
     $this->assertEqual($edit, $gateway->getCustomConfiguration(), 'SMS Test gateway successfully configured.');
   }
 
diff --git a/src/Tests/SmsFrameworkWebTestBase.php b/src/Tests/SmsFrameworkWebTestBase.php
new file mode 100644
index 0000000..fafc8a8
--- /dev/null
+++ b/src/Tests/SmsFrameworkWebTestBase.php
@@ -0,0 +1,39 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\sms\Tests\SmsFrameworkWebTestBase.
+ */
+
+namespace Drupal\sms\Tests;
+
+use \Drupal\simpletest\WebTestBase;
+
+/**
+ * Provides commonly used functionality for tests.
+ */
+class SmsFrameworkWebTestBase extends WebTestBase {
+
+  public static $modules = ['sms', 'sms_test_gateway'];
+
+  /**
+   * The gateway manager.
+   *
+   * @var \Drupal\sms\Gateway\GatewayManagerInterface
+   */
+  protected $gatewayManager;
+
+  public function setUp() {
+    parent::setUp();
+    $this->gatewayManager = $this->container->get('plugin.manager.sms_gateway');
+    // Add an instance of test gateway and set it as default.
+    $this->gatewayManager->addGateway('test', ['name' => 'test']);
+  }
+
+  public function setDefaultGateway($gateway_id) {
+    // Ensure gateway is enabled first.
+    $this->gatewayManager->setEnabledGateways([$gateway_id]);
+    $this->gatewayManager->setDefaultGateway($gateway_id);
+  }
+
+}