Abstract: A method and apparatus for activating an emergency telephone mounted upon a structure, wherein the telephone is activated as a result of an impact by an object upon the structure causing the telephone to go off-hook active with immediate automatic connection to another telephone.

Abstract: A telephone is provided with a means for automatically generating ringing tones to be heard by a user over ambient noise and in spite of any muffling environment in which the telephone may be located. The ambient noise is measured to determine its amplitude and frequency characteristics and appropriate amplitude and frequency characteristics of ringing tones to be heard by a user over the ambient noise are calculated and generated. The degree to which the ringing tones are muffled by the muffling environment is calculated and suitable amplitude and frequency characteristics of further ringing tones necessary to be heard by a user in spite of the muffling environment are calculated and further ringing tones having the suitable amplitude and frequency characteristics are generated.

Abstract: A telephone that has dual keypads, wherein one of the keypads is a standard 12 number (1-9, 0, #, and *) keypad and the other keypad comprises a plurality of keys having a single character on each key. When a character key is pressed, it generates a DTMF pair corresponding to one of the 12 standard DTMF pairs.

Abstract: A telephone headset interface circuit is coupled to a telephone line to extract power for use by a headset amplifier and is particularly adapted for use with telephone handsets having dynamic or electret microphones. The telephone line connects a telephone to a service system, such as a Central Office, a PBX system, or a Key system. The interface circuit includes a power extraction circuit having a plurality of circuit portions, each one coupled to a corresponding one of the telephone line wires for providing a predetermined output voltage, so that substantially identical electrical impedance characteristics are introduced to each such wire. An amplifier is coupled to the telephone handset such that the predetermined constant output voltage is coupled to the amplifier to power the amplifier from the telephone line when the telephone includes an electronic microphone handset.

Abstract: A head-supported two-way communication system. The system combines a thin bstrate forehead or head-bone microphone, a noise filter embedding the microphone, a universal impedance matcher connecting the microphone to a two-way radio, an unobstructed and unfettered-access push-to-talk switch, and a pair of rigidly positionable noise protected speakers, all secured to a head-supported structure permitting proper location of the embedded microphone, the switch, and the speakers for a particular user and application.

Abstract: A method and apparatus for controlling ring volume if a telephone by memorizing the ring volume in state where a telephone call is answered responsive to ring tone of the telephone and then, generating the ring tone with the memorized ring volume when a next telephone call occurs.