Cisco Telephony How To
How to edit network configuration on a Cisco IP Phone
Once on the network settings page press **# to enable the edit button.
How to reset a Cisco IP Phone to Factory Defaults
Do a power cycle (unplug the phone and connect it again). When the headset button lights up, press and hold the # key. You should see the phone showing "Reset sequence detected". Within 60 seconds to enter the reset sequence: 123456789*0#. The phone will ask if you need to keep network config or not. Press 2 and you are done.