The default password for phones registered to CME is "Cisco" (with capital C).
Can you edit phone's cnf file? If yes, you can and these thing in it:
If the password "cisco" didn't work, you can set a new password in CCM: CCM Admin -> Device -> Device Setting -> Common Device Configuration -> Local Phone Unlock Password. You have to reboot 3911 after that. Note that, If 3911 is using a customized "Common Phone Profile", then you have to modify corresponding one.
Thnks for the respose.
Its a new phone. What happened is, it connected to network and registered with callmanager once. Then we have removed the device and connected to user desk but it is not working (keep on restarting). Which was repeating for all new phone which am configuring (My network already running with same 3911 model phone).
Finally what I found is, new conneting phones are working fine after down grading the firmware from SIP3951.8-1-4a to SIP3951.8-1-2SR1.
But the phone which I have registered first (SIP3951.8-1-4a) are keep on restarting and not registering even after changing the device default (phone loadname also) to SIP3951.8-1-2SR1.