--- C:/Users/Sina/Downloads/sms_simplegateway/old/sms_simplegateway.module	Sun Oct 09 07:43:52 2011
+++ C:/Users/Sina/Downloads/sms_simplegateway/new/sms_simplegateway.module	Sat Oct 25 21:33:51 2014
@@ -230,7 +230,10 @@
   $query_string = http_build_query($params, NULL, '&');
 
   if ($method == 'GET') {
-    $url = $url_base . '?' . $query_string;
+    if(strpos($url_base, "?") === false)
+      $url = $url_base . '?' . $query_string;
+    else
+      $url = $url_base . '&' . $query_string;
     $http_result = drupal_http_request($url);
   }
   elseif ($method == 'POST') {