Would it be possible to replace/wire the buttons on a keypad with buttons from this old phone?
The buttons on the round pad are in a matrix. The ones ok the remote door lock interface is also in a matrix, but I can't be sure based on just the picture.

Since a button is nothing more than two nodes that are connected when pressed, you can easily extend it.

Cut all the traces from the round pad so that each button is independent. Remove the metal discs from the buttons on the square pad. Now extend them by soldering wires between one and the other. A bit messy if each of the buttons on the square pad do not use common grounds, but doable. 26 wires at most. I recommend wire like 24 or 26 awg just to make the bulk less difficult. I use IDE/PATA cables.

This is the same thing that game console modders do all the time to swap one remote for another.



Ben heck put a Xbox 360 wireless controller inside an original Xbox "duke" controller. Same exact procedure.