Abstract: A standard phone jack is provided with a lock cylinder having a rotatable contact arm which is capable of rotating between a first open circuit position when in its locked position and a second closed circuit position where it engages a wire contact to provide access to a dial tone. In such a manner, it completely cuts off all access to the outgoing phone line when locked so that no calls may be made or received by unauthorized users, nor can charge calls or collect calls be accepted by unauthorized users.