I have set up some 4610 and 4620 phones on the IP Office 3.0 and they work fine until I need to change the extension. Normally, in Definity world, I do a 'Mute' 'r-e-s-e-t' and it would ask for new IP info and then when it came back up it would ask for the extension#. The IP Office asks for the new IP info but not the extension#. Any clue on resetting the extension# on these phones?