We currently use Cisco Call Manager for our VOIP Telephones. We have a building on campus that will be utilized as an Emergency Command Post and the Military Personel use an Avaya 9640 VOIP Phones. They would like us to register the devices in the Call Manager so when they come up, they can use their phones on our system. Is there any problem in registering an Avaya VOIP Phone in the Call Manager? Will there be any limitations with an Avaya Phone compared to a Cisco Phone registered in the Call Manager?