Change webservice outgoing gateway

How can I change webservice out going SMS gateway ?

I want to differentiate SMS Gateway between a web service and a website.
Please help me to do it.
Thank you.

I detect single SMS and bulksms from queue size and change smsc gateway
you can edit /sendsms/fn.php and add comment this line

          $c_smsc = $db_row['smsc'];

and add

            if ($c_queue_count <= 1){
                    $c_smsc = "SMSCNAME";
            } elseif ($c_queue_count > 1  ) {
                    $c_smsc = $db_row['smsc'];