An LIR includes the Public-User-Identity AVP, which contain a UA’s actual PUID. The HSS responds with the assigned S-CSCF server for this PUID. The answer is in the form of a Location Info Answer (LIA). The LIA includes the assigned S-CSCF in the Server Name AVP.

If the S-CSCF returned in the LIR is this Oracle Communications Core Session Manager, then it performs unregistered termination services for this UA. (This situation indicates that the UA is currently unregistered.) Such services could include directing the call to voice mail. If the HSS returns an S-CSCF in the LIA that is not this Oracle Communications Core Session Manager, it forwards the request to that S-CSCF.