First, minimalistic version

gatewayBackend.php

@@ -9,11 +9,52 @@ interface gatewayBackend
 	 * @param String $sessionId
 	 * @return String $token
 	 */
-	public function get_token($username, $password, $ip, $sessionId);
+	public function getToken($username, $password, $ip, $sessionId);
+        
+        /**
+         * 
+         * @param String $token
+         * @param String $sessionId
+         * @param String $ip
+         * @return Boolean
+         */
+        public function checkToken($token, $sessionId, $ip);
+        
+        /**
+         * removeToken() Remove a logged out user's token
+         * 
+         * @param String $token
+         */
+        public function removeToken($token);
 
 	/**
-	 * @param
+         * sendSMS()
+         * 
+         * Send SMS message to recipient's phone number
+	 * @param String $token
+         * @param String $recipient
+         * @param String $message
+         * @param Array $passwordLocations
+         * @return Boolean
 	 */
-	public function 
+	public function sendSMS($token, $recipient, $message, $passwordLocations);
+        
+        /**
+         * auditLog() Log audit messages
+         * 
+         * @param String $ip
+         * @param String $event
+         * @param String $message
+         */
+        public function auditLog($ip, $event, $message);
+        
+        /**
+         * messageLog() Log sent messages
+         * 
+         * @param String $recipient
+         * @param String $message
+         * @param String $ip
+         */
+        public function messageLog($recipient, $message, $ip);
 }