Twilio API for SMS based web application

A few months ago I worked in a web project where we had to develop web & SMS application. Our main project is fully web application where we need to integrate SMS and some voice feature. We also wanted to integrate this feature easily and cost effectively. After some R&D in google search we found several web services for this purpose. Among all the services we liked Twilio.

There are several reasons to choose Twilio. One of the most important reason is, its very easy to integrate Twilio’s REST API. The price is also cheap compare to other services. In this post I’ll not write details about Twilio. You can easily learn more about it by there web site. I’ll mention some features that we integrated in our application.

Our project is developed based on CodeIgniter framework. So we just downloaded the REST library provided by Twilio and dropped in our libraries folder.

Then I wrote a class to use the Twilio API to serve our application purpose. Our application’s task was:

1. Send SMS
2. User can search and select custom phone number
3. User can buy a local phone number

Here is my class that I’ve written. You’ll see this class named is Smsapi and its located in the libraries folder follow the above image.

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<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');   /**  * This is a wrapper class for sending sms. Twilio Api Custom Library suitable for our CI Project  * @author: Mahmud  * @category Library  */   // Include the PHP TwilioRest library require "twilio/twilio.php";   class Smsapi {     private $client;     private $AccountSid;     private $AuthToken;     private $CallerID;     private $ApiVersion;     private $CI;     private $SMS_Callback;     private $VOICE_Callback;     private $VOICE_fallback;     private $VOICE_status;       function __construct(){         // Twilio REST API version         $this->ApiVersion   =   "2010-04-01";           $this->CI           =   &get_instance();           // Set our AccountSid and AuthToken         $this->AccountSid       =   $this->CI->config->item('twilio_sid'  );         $this->AuthToken        =   $this->CI->config->item('twilio_token');         $this->SMS_Callback     =   $this->CI->config->item('twilio_sms_callback');         $this->VOICE_Callback   =   $this->CI->config->item('twilio_voice_callback');         $this->VOICE_fallback   =   $this->CI->config->item('twilio_voice_fallback');         $this->VOICE_status     =   $this->CI->config->item('twilio_voice_status');           // Outgoing Caller ID you have previously validated with Twilio         $this->CallerID     =   $this->CI->config->item('twilio_phone');           // Instantiate a new Twilio Rest Client         $this->client       =   new TwilioRestClient($this->AccountSid, $this->AuthToken);     }       /**      * This function is a wrapper to send SMS to a phone number. You should use this method for all type      * of SMS message sending.      * @param string $number phone number to whom sms will send      * @param string $message message that will send to the phone number      */     public function send_sms($number, $message){         $response = $this->client->request("/{$this->ApiVersion}/Accounts/{$this->AccountSid}/SMS/Messages",                 "POST", array(                 "To" => $number,                 "From" => $this->CallerID,                 "Body" => $message         ));         if($response->IsError){             $error  =   "Error: {$response->ErrorMessage} " . " File: Smsapi.php 42 no line. Number: $number";            // echo $error;            log_message('error', $error);            return FALSE;         }         else{             //echo "Sent message to $number";             return TRUE;         }     }       /**      * This function search for available mobile numbers based on ZIP code      * @access public      * @param string $zip ZIP code of US or Canada      * @param string $country US or CA      * @return BOOLEAN TRUE for get result and FALSE for error or no result      */     public function search_mobile_numbers($zip='', $postal='', $country='US', $failsearch=FALSE){         $SearchParams['InPostalCode']   = !empty($zip)    ? $zip    : '';         $SearchParams['NearNumber']     = '';         $SearchParams['Contains']       = '';         $SearchParams['AreaCode']       = !empty($postal) ? $postal : '';           /* Initiate US Local PhoneNumber search with $SearchParams list */         $response = $this->client->request("/{$this->ApiVersion}/Accounts/{$this->AccountSid}/AvailablePhoneNumbers/$country/Local",                          "GET",                           $SearchParams);           if($response->IsError) {             return $response->IsError;         }           $AvailablePhoneNumbers = $response->ResponseXml->AvailablePhoneNumbers->AvailablePhoneNumber;           if (empty($AvailablePhoneNumbers)){             $AvailablePhoneNumbers  =   "No available numbers in your zip code";             if ($failsearch){                 //now check only available number not need to zip code specific                 $SearchParams['InPostalCode']   = '';                 $response = $this->client->request("/{$this->ApiVersion}/Accounts/{$this->AccountSid}/AvailablePhoneNumbers/$country/Local",                              "GET",                               $SearchParams);                   if($response->IsError) {                     return $response->IsError;                 }                   $AvailablePhoneNumbers = $response->ResponseXml->AvailablePhoneNumbers->AvailablePhoneNumber;             }         }           return $AvailablePhoneNumbers;     }       /**      * Buy mobile phone number      * @param STRING $number the phone number user wants to buy      * @return mixed TRUE for success and string for error message      */     public function buy_mobile_number($number){         /* Purchase the selected PhoneNumber */         $response = $this->client->request("/{$this->ApiVersion}/Accounts/{$this->AccountSid}/IncomingPhoneNumbers",                                      "POST",                                      array(                                          'PhoneNumber'          => $number,                                          'SmsUrl'               => $this->SMS_Callback,                                          'SmsMethod'            => 'POST',                                          'VoiceCallerIdLookup'  => TRUE,                                          'VoiceUrl'             => $this->VOICE_Callback,                                          'VoiceMethod'          => 'POST',                                          'VoiceFallbackUrl'     => $this->VOICE_fallback,                                          'VoiceFallbackMethod'  => 'POST',                                          'StatusCallback'       => $this->VOICE_status,                                          'StatusCallbackMethod' => 'POST',                                      ));           if($response->IsError) {             $err = urlencode("Error purchasing number: $response->ErrorMessage");             return $err;         }           return TRUE;     } }   ?>

I also provided the constant variables in config.php. You’ve to provide your own API Key, token, Twilio Phone Number in this variables.

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//Third Party Library Configuratio $config['twilio_sid']           =   'XXXXXXXXXXXXXXXXXXXXXXXXXXX'; $config['twilio_token']         =   'XXXXXXXXXXXXXXXXXXXXXXXXXXX'; $config['twilio_phone']         =   'XXXXXXXXXXXXXXXXXXXXXXXXXXX'; $config['twilio_phone_display'] =   'XXXXXXXXXXXXXXXXXXXXXXXXXXX'; $config['twilio_sms_callback']  =   $config['base_url'] . '/sms'; //it should be our application's dedicated sms url $config['twilio_voice_callback']=   $config['base_url'] . '/voice'; //it should be our application's dedicated voice url $config['twilio_voice_fallback']=   $config['base_url'] . '/voice/fallback'; $config['twilio_voice_status']  =   $config['base_url'] . '/voice/status';

In my class you’ll see 3 functions

1. public function send_sms($number, $message);
2. public function search_mobile_numbers($zip=”, $postal=”, $country=’US’, $failsearch=FALSE);
3. public function buy_mobile_number($number);

Using send_sms() function you just have to provide the phone number and message to send as text. Using search_mobile_numbers() function you can search and get the available phone numbers based on ZIP, POSTAL and Country code. And the final function buy_mobile_number() you can purchase the number from Twilio and from then that number will be not available for other users.

We also integrated some other features like some voice, automatic SMS answer when user send text to a number. But for simplicity I’ve not described them in this post.Hope this article will help you to work on Twilio.