Split form fiels data to 2 different 3rd party field

Hi guys,
I’m trying to connect with CRM that requires to get the phone field as: cellphone + cellphoneprefix

I tried to use hooks but it’s not working ??
The code I’ve added to functions.php is:

function service1_action_callback($response, $results){

       try {
                $cellphoneprefix = '';
                $cellphone = '';
                $telephonePrefix = '';
                $telephone = '';

                $tel = preg_replace('/[^0-9]/', '', $_POST['tel0']);
                                if($tel){
                                                if(substr($tel, 0, 2) == '05'){
                                                                $cellphoneprefix = substr($tel, 0, 3);
                                                                $cellphone = substr($tel, 3);
                                                }else{
                                                                $telephonePrefix = substr($tel, 0, 2);
                                                                $telephone = substr($tel, 2);
                                                }
                                }

              $results['attach'] = $tel;

       } catch(Exception $ex){

              // indicate failure by adding errors as an array

              $results['errors'] = array($ex->getMessage());

       }

}//--  function service1_action_callback

add_action('Forms3rdPartyIntegration_service_a0', array(&$this, 'service1_action_callback'), 10, 2);

Print screen of the 3rd-parety settings in my admin: https://i.imgur.com/I5YhkTl.jpg

https://www.ads-software.com/plugins/forms-3rdparty-integration/