[Serusers] Routing Logic Question

Hi All. I'm a confused when handling CANCEL messages when the call is between my SER proxy and a PSTN gateway. I've had a few discussions with Jan regarding when lookup("location") needs to be called and as I understand it CANCEL is sort of an odd message that is not really mid-dialog, and therefore not record-routed. So lookup("location") needs to be called before t_relay()ing a CANCEL. This is fine for calls between two UAs on the same SER proxy since both UAs have a contact record and lookup("location") will return TRUE. But when calling SIP->PSTN, and you hang up from the SIP side, the CANCEL is sent from the SIP UA to SER. Then SER tries to find the contact record in the location table, but since this is a PSTN destination, lookup(location) returns false, thus a 404 and the CANCEL is not relayed to the PSTN gateway. So what is the best way to process CANCEL messages? Just ignore lookup("location") when it returns false for CANCEL messages? My basic ser.cfg is like this: route { # sanity checks if (method!="REGISTER") record_route(); if (loose_route()) { t_relay(); break; }; if (uri!=myself) { t_relay(); break; }; if (uri==myself) { if (method=="REGISTER") { save("location"); break; }; if (!lookup("location")) { sl_send_reply("404", "Not Found"); break; }; }; t_relay(); } Regards, Paul