The Texas Chainsaw Massacre 2 (1986)

Chosen answer: That's how telephones worked back then. It has to do with the lack of a disconnect signal being sent by the called party, which phone companies have now. Back then when someone called another person, they were paying for the call and thus it was felt that they're entitled not to be hung up on and the line would not be "free" for the person being called, even after they hung up. This also meant if someone was called and they picked up in one room, they could say "hold on I'm going to switch phones", hang up, go to another room and pick up the phone and the caller would still be there. It was also a great way to scam or annoy people by calling them and not hanging up. Some countries still maintain this method of operation, largely because some people have become used to it, although nowadays it's by choice, not by technical limitation, and the length of time the line is held open is significantly reduced.