I’ve been getting this call a couple of times a week for about a month and have not received any bills, either. I figured this would make a good demonstration of how to record phone calls in high quality. This Panasonic cordless phone has the smaller 2.5-millimeter jack with three conductors. I made an adapter cable using a 2.5-millimeter plug with the tip being a microphone in and ring (middle conductor) being output and wired to the black RCA jack. The third conductor, the sleeve is a common ground for the output and the input. The red RCA jack is for a microphone and it has about 1.5 volts of plug-in phantom power for electret condenser microphones.