If you’re having trouble getting a Cisco phone to register, it may need to be reset to factory defaults.

When a Cisco phone is factory reset, the following settings are erased or defaulted:

Information Erased:

• ITL (Initial Trust List) file
• CTL (Certificate Trust List) file
• LSC (Locally Significant Certificate) file
• Phone application
• Call History

Reset to Default:

• All user settings:
  – ring tone, screen brightness, volume, etc…
• Network settings:
  – DHCP is enabled by default

Certificate files authenticate and decrypt the (AES) encrypted TFTP configuration files issued during registration.
Therefore, an invalid ITL (and/or CTL) file will prevent a phone from being re-deployed on a different system.

Deleting the ITL file:

1. Goto Settings ➤ Security Configuration ➤ Trust List
2. In the Trust List menu, unlock the phone by pressing **#, an open padlock icon is displayed.
3. Select the ITL file to delete, press Unlock softkey, press more, press Erase
   The phone should indicate that it’s deleting the ITL file, and reboot.

If the phone will still not register, reset it to factory defaults.

Generic factory reset procedure:

1. Press and hold #, power cycle the phone
2. When an LED starts to flash, release #, and enter:• Soft Reset (delete files): 123456789*0#
   • Hard Reset (format flash): 3491672850*#The phone will display Upgrading and erase its configuration.
   If a Soft reset doesn’t work, try a Hard reset!

Other codes:

• To unlock read-only menu settings, goto Settings and enter: **#
  The phone will display Settings Unlocked and allow changes.
• To reboot a phone from the keypad, goto Settings and enter: **#**
  The phone will display Resetting and reboot.

Reset Specific models:

Factory reset procedures for the following models:6901, 7841, 7940, 7941, 7960, 7961, 8831, 8841, 8851

Cisco 6901 phone Factory Reset:

1. Unplug the power cable from the phone, then plug it back in. The phone begins its power-up cycle.
2. While the phone is powering up, press and hold # button until the Line LED turns green.
3. Release the # button and press 123456789*0#
   The line button LED turns red. The phone reboots when it is finished.