In firmware revisions inferior to 3.3, on receiving a check-sync SIP NOTIFY event a phone would check the timestamp or the hash of the configuration files on the server and reboot if that is changed.

One of the features introduced by firmware revision 3.3 is that phones will reboot when receiving a check-sync SIP event only if certain parameters have changed. These parameters apparently depend on the exact firmware revision and the phone model itself.

There is a way to force a phone to reboot even if the configuration files have not changed. The parameter that need to be changed is at:

Devices > Phones> {PHONE} > SIP > specialEvent > checkSync.alwaysReboot

It is unchecked by default, since this is a major feature introduced by Polycom with firmware 3.3 (i.e. the ability to change some parameters without phone rebooting).

Check this parameter and send profiles to the phone.

Please note that the "Restart" button will just send a check-sync event to the phone. This can be confusing, since if alwaysReboot is not checked and nothing has been changed on the profiles, the phone would not actually reboot (But remember that it still checks the configuration files on the server).