I am seeing some phone in my CUCM 22.214.171.12400-3 cluster unregister with a reason code of 16, I looked it up and it means DuplicateRegistration. What does that mean though? That I have 2 phones trying to register the same MAC address??
ReasonCode 16: DuplicateRegistration. This means that Cisco Unified CallManager detected that the same device was registered on two nodes at the same time. When this happens, Cisco Unified CallManager sends a restart request to the phone to force the phone to register with only one Cisco Unified CallManager.