[Freeswitch-users] send and receive call for non registered endpoint.

I have a IAD with PRI interface and  multiple  SIP users. I do not want to register each user on Freeswitch. I do still want each user to be able to send call and receive call.  For sending call from IAD to FS, since all the sip calls have to go through SIP-router (Kamailio) and then routed to FS, I am thinking using X-AUTH-IP in ACL so no auth required.  For   receiveing call from FS, I am thinking either to setup each user on FS and  manually create contact information and make them never expire or add cidr to each user and modify dial-string to use cidr instead of sip contact. Are these approaches workable?  What is the best way to do this? Gary