Most of the time Cisco IP phones boot up correctly and attempt to locate the appropriate network resources (CallManager IP, TFTP server, IP address, default gateway, DNS, etc.).
Occasionally this process doesn’t work correctly due to firmware issues or a failed firmware upgrade/downgrade. When this happens there are two reset sequences that may bring your phone back to life! Both procedures are nearly the same, but use different digit strings based on the type of reset you wish to perform. The first process removes all the phone configuration stored on the phone. The second process formats the flash memory on the phone and removes the firmware itself.
1. Unplug the power cable from the phone and then plug it back in.
The phone begins its power-up cycle.
2. While the phone is powering up, and before the Speaker button flashes on and off, press and hold #.
Continue to hold # until each line button flashes on and off in sequence in amber.
3. Release # and press
process 1 use 123456789*0#
process 2 use 3491672850*#
You can press a key twice in a row, but if you press the keys out of sequence, the factory reset will not take place.
After you press these keys, the line buttons on the phone flash red, and the phone goes through the factory reset process.
Do not power down the phone until it completes the factory reset process, and the main screen appears.
If you followed process 2 be prepared to wait for up to 20 minutes for the phone to retrieve a copy of the firmware image from the TFTP server. Remember that since you removed the firmware completely there won’t even be the comforting Cisco labeled splash screen on startup. Be patient!