When we call extensions from the DX650 endpoint, the call is connected at random. My phone is receiving a ringback tone, but when the user answers the call, it continues to ring. Endpoint is currently registered with CUCM 12.5
Does the user pick up the handset to answer the call in the non-working scenarios. Is it possible that the hookswitch button is stuck? I have seen that happen with regular ip phones before.
For me this sounds like the problem with call capability. Try disabling video on the phone configuration page of the DX650 and then call the same IP phone.
