Smart telephone design-caller identification and answering machine

This paper presents some advanced facilities and services related to the use of everyday telephones. The caller identification and answering machine are advanced telephone functions. The telephone system can be used as a tele-security system. This research work is based on the potential use of a low cost 8-bit microcontroller. The caller identification (caller ID) system is a feature of digital telephone networks and is supported by signaling system no. 7 (SS7) which uses a separate call data circuit. The caller ID information is transmitted on the subscriber loop using frequency shift key (FSK) modem tones and data is embedded between the first and second ring of the ringing signal. A caller ID decoding circuit has been designed for decoding the FSK modem tone and the appropriate ASCII code is displayed in the LCD unit. An answering machine is a device that answers the telephone calls in the absence of the called party and records the incoming message into a cassette. A ring detector circuit, outgoing message (OGM) sender circuit, tape driver circuit, dual tone multiplexed frequency (DTMF) encoder circuit and calling party control (CPC) circuit have been developed for the answering machine device. The DTMF generator circuit and sensor signal management circuit have been integrated to provide a tele-security system. A PIC 16C84 (8-bit microcontroller) controls all logic operations as it was programmed. Software has been produced in assembly language for programming of the microcontroller.