While upgrading a call center from firmware version 7.5.1a to 7.5.2b I have phones that request a reboot for provisioning(4) but seem to get stuck at this point and do not respond to reboot commands. I end up having to have the customer power cycle the phone and I'm able to push the update. Only thing in common with these phones are that they are rarely used or have been sitting for a while. Thought it was an issue with having Do Not Disturb active but the testing I have done shows that it does not seem to affect the upgrade process. Any thoughts on what it could be?
This is an Asterisk setup and I do not have access to the phones configuration utility.