[Freeswitch-users] How do I carry dial-in number to extension?

I have two DID's registered at my SIP. This works nicely, I've created groups for holding the local extensions, and one of my phones can subscribe to two SIP accounts, so I can distinguish between if it's one or the other DID (it will show which SIP account is called in the display). Problem is, another one of the phones can only subscribe to one SIP, and has no display (linksys sipura 901), any idea how to accomplish that I can distinnguish between the DID's on that one?