[Serusers] Multiple organizations using same SER box

I'm wanting to let several companies share one of my SER boxes. These companies have overlapping extensions for their phones (the registrations are unique, though). Is there something I could do, perhaps with avp's, to denote which organization a particular call should be subject to? For example: Company 1 Exten: 1234 SIP user: alice Exten: 1235 SIP user: bob Company 2 Exten: 1234 SIP user: eve Exten: 2345 SIP user: frank If bob calls alice by dialing 1234, is there a way to look up the organization, and rewrite the uri to go to the correct place so that alice doesn't accidentally get sent to eve? I would like to do this without static rules in the ser.cfg so that I can just set the organization by adding an avp when I create the users. I am also using CPL to handle dialplan type of issues already. Anyway, thanks for any help!