[cisco-voip] Branch Office CME SIP trunk question

[cisco.voip]

All,
I have a branch office with the latest CUCME, about 15 users, the CME 
points everything back to HQ Call Mgr v7.1.
I am looking for a solution that could display on the CME connected 
phones, when the SIP Trunk is down.
So if the Branch loses it connection, the users know their phones aren't 
working by looking at the phone, vs get the dial tone and
dial with no results?

Thanks,