Telelogic, Inc.

Richard M Simmons

Telephone calls from an extension (32) on a private branch exchange (PBX) (14) are directed by an automatic telephone dialer (12a) to an outside line (18) of a local operating company or to a dedicated line (22) connected to the facilities of a specialized common carrier. The dialer is connected to an extension line (36) simply as another extension. A call from an extension (32) requesting an outside line is directed to the extension occupied by the dialer (12a), and a ring detector (40) detects the resultant ringing signal and alerts a controller (44). The controller sends a dial tone to the calling extension (32) and records the resultant dialed digits. It then momentarily interrupts its off-hook signal to cause the PBX to place the calling station (32) on hold and dials the appropriate destination. Once the dial has been replaced, it 'hangs up,' causing the PBX to connect the calling extension (32) to the destination that the automatic dialer has called.

Call-routing device

A videotex system employs a subscriber unit (22) at a remote location such as a user's home. The subscriber unit (22) employs the user's telephone tone dial (26) for transmission to a communications module at a central location and uses the user's television set (24) for display of information received as frequency-shift-keying signals by the user's telephone (20). At the central location, the system employs a transmission memory (16) containing the currently desired display, and a microprocessor circuit (28) reads the contents of the transmission memory (16) to send it by FSK signals to the remote location. The information contained in the transmission memory (16) comes from a host computer, and an antiquity memory (50) having locations corresponding to those of the transmission memory (16) has its associated location reset whenever a transmission-memory location is written. That antiquity-memory location is then incremented whenever the information is sent, and the microprocessor (28) at the central location repeatedly sends the contents of the transmission-memory location that has been sent least frequency as indicated by the contents in the antiquity memory (50).

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Cambridge, MA, United States of America

Richard M Simmons