I have found some instructions on how to do this via a handset and am just waiting for an RJ11 to RJ45 cable so that I can try it."

Don't you already have handsets?



"I already tried the SD card from the MCP in the MP20 and it didn't boot up?"

An MCP card doesn't use a sd card so no that is not going to work.


No offence but are you capable of reprogramming from scratch? Just by the questions you are asking it seems like you are not that experienced with the system.It may pay to get a tech in to do the work for you.