9951 going in Preservation mode

[Amit23]

having cucm 105.x and phones model:

9951

7821

dx650

and vg204..

sometime on call with other party, 9951 going in preservation mode but servers are running fine..

what could be issue and how can resolve it as it is happening for 9951 models only?

[Venkatesh Perumal]

Hi,

have you performed any recent upgrade/downgrade of phone firmware and since when do you notice this issue.

relates to the bug: CSCte00793

Symptom:

Phone may momentarily disconnect from the call manager. If there is an active call, the phone will go into preservation mode to maintain the call.

Conditions:
Condition may occur when the phone is in encrypted or authenticated security mode.

Workaround:
The phone will re-register within 30 seconds on its own if the phone is idle. If there is an active call the phone will wait until the call terminates before registering. No user intervention is required.

Product:

Cisco Unified IP Phones 9900 Series

try upgrading the phones to the latest firmware, in case running on lower version.

-Venkatesh.

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