There are two common possible causes to an issue like this:
Something Network/SIP Signaling Related
An issue with the phone's configuration file or other local issue
I'm assuming you have a boot server (FTP, HTTP, TFTP) ?
To help with troubleshooting the issue, I'd consider the following:
- Did you upgrade from a previous version of SIP software? What version?
- If so, the files may not have been migrated properly. Try re-provisioning a troublesome phone from Polycom's public server: http://voipt2.polycom.com/331f and configure the phone from the web interface, and monitor for further issues.
- Does the issue occur on a previous version of software? If not, what version?
- Does the issue only recur on the same phones, or is it random?
- If the issue is limited to specific phones, what is the Difference between them and the phones that don't have the issue?
- Do the reboots follow a pattern in the user's usage of the phone?
- If so, what is the user doing at the time of the reboot?
- Are there any error messages on the screen prior or during the reboot?
- Do the softkeys (bottom row) disappear prior to the reboot?
You may consider opening a Service Request at http://support.polycom.com, if you need someone to review your configuration files and/or phone logs, or your Certified Reseller for network and PPI services.