I do computer work for a small business and they have a KX-TA624 system installed. It was installed by some guy a few years ago who charges way too much and has a horrible attitude. I've never worked with phone systems before but I told them I'd take a look at it anyway. They'd like to change their voicemail configuration around..for example change one phone to be extension 111 instead of 125. I believe the installer set a password which we don't know. I'd like to reset the whole system and reprogram it fresh since we don't know the password. However, I have no clue how to do this. If anyone could please provide me with some type of guidance I'd greatly appreciate it.

Thank you very much.