Phones will registered and have the speaker enabled. After first call, phone locks up, speaker light is lit, and phone is unregistered in CCM. I've tried the alternate factory reset code and reloaded the firmware with same result.

We're currently running firmware 8.3.3 but have had similar issues with firmware 8.0.1 till now.

As for same switches - no. multiple switches / multiple locations

If I replace the phone, the replacement phone does not have a problem. However the replaced phone repeats it's problem regards of the switch, port, network cable.

We're running CCM 4.2.3 and the phone has no shared lines.

We'll try the 8.3.4SR1 firmware on Monday. I did not see the release notes on this version. What is issues are resolved in it?

Upgraded to 8.3.4SR1 with the same results. The only difference is the screen does not go blank now

I have the same issue with my 7961 phone. IS there any fix for this issue?

Thanks

I haven't found one and since we don't carry maintenance on them - I'm screwed