Abstract

A telephonic communications system (FIGS. 1 and 2) designed to use the availability of ordinary subscriber telephone lines to which a telephone instrument (312) is conventionally attached. Whenever it is desirable for a caller (306 or 309) to transmit data from a calling telephone (305, 308 or 316) a special code is input to the called telephone (312 or 301) which, through detection circuitry, activates an intercept system (184A of FIG. 11) within the called telephone, which inhibits audible ringing of the called telephone instrument and connects a second system (FIGS. 10 and 14) incorporated within the same called telephone instrument for auto-tuning, processing, and re-transmitting from the called telephone subsequent received data to a remote addressable portable data unit (302 or 311). The remote data units (302 and 311) communicate with the telephone instrument (301 and 312) via a radio frequency data link, through which it may either receive data from or transmit data to the telephone instrument. The communication system can operate without the need for human intervention at the calling or called telephone instrument and neither calling nor called telephone instrument need be manually placed off-hook for end-to-end operation.