i m running cucm manager 11 cluster with 3925 voice gateway in mgcp protocol.
i connect 2 qsig pri's to Avaya ver 7.6 .
All calls working fine both direction.
the issue is the name display that does not display from cisco phone to Aavaya phone. from Aavaya to Cisco the name display fine.
It might be bug as in earlier cucm releases, try to delete route group and route list and recreate them again and check. Check below link for more info.