Extensions and SIP AoRs


Does anyone know if Asterisk can be configured with essentially two user IDs - one that represents the PBX extension (e.g., 1234) and another that represents the user portion of the SIP AoR? (e.g., “alice” as in alice@domain.com).

If so, how is this configured? Of course Asterisk would have to map these two ids.

Is this possible?