User Static Registration

Typically a SIP client sends a SIP Registration to FreeSWITCH for a given user.

Instead of the SIP Client having to maintain a SIP Registration to FreeSWITCH. Is there a way for a user to have a static registration (hardcoded). Of course this means the SIP Clients IP address would never change.

I would like to have the following:
When someone rings user 1000. It rings all registered devices for 1000 plus a Static registration/route 1000@domain