My uncle owns a restaurant. There is a phone in the kitchen that is the main line. There's also a pay phone near the bathrooms. If you were to call the payphone it will ring along with the phone in the kitchen.
However if you make a call on the pay phone, someone in the kitchen can pick up the main phone and listen to your pay phone conversation.
How is this possible? Are the lines crossed somewhere? Did the phone company screw up when they installed the pay phone?
Or maybe my uncle was reading a few PLA issues and he's a phone phreak himself, but never told anyone.
MIB