Dear List

I am currently using the group module to authenticate inbound calls using the From header using the below code:

         if (!is_user_in("From", "1")) {
         sl_send_reply("403", "NOT ALLOWED");
         exit;
         };
         };

I want to now authenticate the Diversion header, when the call is diverted, the same way as above using the group module how could i proceed with this?

thanking you in advance
Phillip