Abstract: The present invention provides an automatic lock for use on a telephone, and comprising a main body for securing to the phone, a slide member slideably mounted in the main body and a spring pressuring the slide member to automatically slide to a locking position over the post of the phone when depressed by the telephone handle to the down position. The slide member is manually slideable against the pressure of the spring away from the locking position to allow upward popping of the post with the slide member being reset to return to the locking position with further depressing of the post.