How to convert wireless intercom from using the AC line to phone line for signal carrier. Many 'wireless FM' intercoms are quickly returned to the seller when consumers discover they don't work. They don't work because most people want to use the intercom on different sides of the house which are on separate electrical circuits or phases of the transformer. If you have a phoneline which is common throughout the house, then let me show you how to adapt your 'wireless' intercom to work for you.