Unable to cancel FWD all on a 7821 phone

[Anshul Tandon]

Only happening with one user. 

There is a user who is using 7821 phone.

Active Load ID:

sip78xx.11-0-1-11

Call manager version :11.0.1.21900-11

When the user  tries to fwd all to an extension, it works fine, but when he tries to cancel the fwd all, phone re-registers it self. On the top of the screen it shows, phone not registered, and then registers back with the FWD all config still there. 

Tried to pick up traces, the phone get unregistered with Reason Code 12.  

Please help how to proceed further. 

[Jaime Valencia]

Do other phones have the same FW?

Does it work from CUCM?

[Anshul Tandon]

yes, it works from CUCM. 

Other phones work fine. 

[Jaime Valencia]

Have you tried swapping the device for a known working device?