Cisco 7811 reboots when the call ends

[RFC_2549]

hello!

a phone 7811 is rebooting when a call ends...so if someone put down the receiver or press the "End Call" button it reboots. I tried to reset the phone from CUCM, the problem still shows up, what can I do?

Edit: the problem shows up even if someone use the speakerphone button

Edit: we changed phone and the problem persist

Thank You

Giulia

[Leo Laohoo]

We can't read your mind.
You need to furnish more information.
The most important of which is: What firmware are the phones and CUCM running on?

[RFC_2549]

Hello!

Neither can I read in Your mind or know what information could serve, however asking is free and answering is not mandatory if it bothers you. The firmware version is sip78xx.12-5-1SR3-74 and the verision of cucm is 

12.0.1.22008-1. We have a lot of 7811 phones with the same firmware version and only one is having issues.

Thank you