Abstract: A telephone disabling device for preventing outgoing calls while permitting a two-way conversation includes a disabling member having a cover portion extending over the dialing device. The member is hooked under a forward part of the telephone and the rear end thereof extends between the laterally spaced uprights forming the hand set cradle. A key lock carried by the disabling member is extendible into a rearwardly opening cavity in the telephone to prevent removal of the member. A modified form of disabling device prevents both outgoing calls and two-way conversation.