I had this idea some months ago. My house came with landline telephone wire, with ports in 3 different rooms. I haven't had a landline telephone since I moved in, so the line is dormant. I'd like to see if I can use it for null modem transfers. Is it as simple as plugging the wires in, then using a breakout block on each end to map them to the right serial port pins? The lines have 4 contacts, and 3 contacts is the minimum for serial null modem, so the hardware is there.