We took a new 7911 out of the box and configured it up on our CUCM system (6.1.3) At first boot, it upgraded it's firmware. Once we'd configured and tested, we took the phone to site. Plugged it in, and now, it constantly reboots. All other phones at site are fine.
The displays the Cisco splash screen, then eventually, for a brief period, shows the normal screen. Then it flashes "Reboot" in the bottom left hand corner, and starts again. (It never shows "Configuring IP", etc)
We've tried doing a factory reset, and it re-images itself fine. It just never completely comes up afterwards. We've removed it from CUCM, but no change (that was more clutching at straws...)
Unless someone has a bright idea, we're planning on sending it back.
We've tried it on multiple switches, including my test switch, and a brand new 48 port PoE switch on which this 7911 was the only device plugged in.
I can't see power being the problem.
I never saw a really failed cisco phones (does not mean there are not), all treoubles were glitches in the dhcp/tftp process, sometime the 7911 thinks to be a 7906 and so on...
If you connect and configure tftpd323 you will see what I mean.
But the phone never gets as far as "Configuring IP" And when a phone says "Configuring IP" the first thing it *actually* does is CDP for it's VLAN...
You cannot be sure of what the phone actually does unless hookup wireshark to it.
Of course, if no packets emitted, it is dead for good.