I am wondering if you can interface a standard, RJ11 telephone through GPIO, and input an output through the phone, even using asterisk to connect to voip. The phone I have is a GE model number 29255ge2 which I believe was made around the late 1990s and early 2000s. I am wondering if you can remove the RJ connector from one end, somehow connect the red and green wire to gpio. One concern I have is that 5 volts will be enough to power the phone, and also making it ring, I know normal ringing voltage is 60v AC I believe.
BTW I am not connecting this to the phone line, also basically if you are misunderstanding this I am basically trying to use the pi as cheapo Analog Telephone Adapter.