[SR-Users] Local subscriber lookup / usrloc

My kamailio implementation sits in front of a group of asterisk servers, when a call comes into kamailio it does a series of checks on the location of the src and dst to determine if the call is allowed. If the src is PSTN and called user is found in the location table the call is passed to an asterisk server for further processing of call forwarding options / voicemail / ring time setting etc. However if the called account is not found (not currently registered) the call is then discarded and voicemail etc can never be accessed. I can add a avp_db_query to fetch user from the subscriber table vs location table lookup. Just wondering if there are any built in functions or other efficient ways to handle this that others are doing. Thanks for any input -Dan