On landlines the call isn't finished until the caller hangs up. This allows features such as "call waiting" to work: the receiver flashes the hook in a certain

On landlines the call isn't finished until the caller hangs up. This allows features such as "call waiting" to work: the receiver flashes the hook in a certain way to switch to the other call. If flashing the hook would disconnect the call, "call waiting" wouldn't work.