[Freeswitch-users] multiple isdn msn on an extension with a single sip account

Hi, I'm evaluating the replacement of an ISDN pbx. One of the things I can't figure out is a suitable replacement for the msn numbers on a phone with a single sip account. The current ISDN phones can be programmed to recognize up to eight different msn numbers. The user of the phone can see and hear which msn number was called. So I've got a BRI or PRI , with multiple msn, feed that into freeswitch and simple extensions like the linksys spa922. I want the extension to ring on more than one msn but I want to be able to see which msn was originally called in the display. Can this be setup using freeswitch and a simple phone??? Any directions would be most helpful. Thank you, Wessel s