I am experiencing an issue when auto registering a 7911G phone in that I am getting the message 'registration: security error', however, the phone is downloading firmware upgrades as normal. The 7911G phones will register if pre-built on call manager & I have restarted TFTP services on all servers but this has not rectified the problem.
Just to confirm:
We are not running security authentication certificates
CUCM Ver is 184.108.40.206900
7911 firmware is SCCP220.127.116.11S (MD5 checksum checked)
All other phone models are successfully auto registering.
Any help would be appreciated.