Hello! My name is Bryson, I'm just a hobbyist. I and a few of my neighbors are looking to create a multi-line, multi-digit phone number, phone system using either our existing pstn wiring in our houses or just diy/test wiring. I have all of the tools necessary. I have no clue where to start, I have looked for hours on google and other search engines on how to do this, I have a basic idea on how to make a dtmf decoder, but the dtmf decoder I saw how to do is only single digit using a MT8870. It only has 4 outputs and I saw a video of a guy saying that you could connect these 4 outputs to a microcontroller of some sort and do multi digit phone number capabilities, but he didn't show us how to specifically do that. Hope this isn't too much to ask! I just have a curious brain like all of us! Any feedback is appreciated!