Abstract: A telephone switch (10) having a data port (DNS) and a vioice port (VPS) is connected to an electronic telephone (12) having a data port (DNT) and a voice port (VPT) through the preferred embodiment (19). A plurality of external devices (13a, 13b, . . . 13n) are also connected to the preferred embodiment (19). When no external device (13a, 13b, . . . 13n) is active, a relay (33) directly connects the voice port (VPS) of the telephone switch (10) to the voice port (VPT) of the electronic telephone (12). When an external device (13a, 13b, . . . 13n) is active, the relay (33) directly connects the voice port (VPS) of the telephone switch (10) to the voice port (V) of the external device (13a, 13b, . . . 13n) and also connects these voice ports (VPS, V) to the voice port (VPT) of the electronic telephone (12) through a resistor network (20, 21, 24, 26, 30) which passes operating power to the electronic telephone (12) but reduces or eliminates audio signals to/from the electronic telephone (12).

Abstract: A call progress monitor for a computer telephone interface system. Energy detectors are connected to receive signals from a telephone line. A bandpass filter is connected to the telephone line, having selectable center frequency. A counter-timer connected to count clock pulses is reset by the energy detector and timing commences in response to the presence of a signal on the telephone line. The counter will result in a center frequency control means for the filter being slewed over a bandwidth of interest, in synchronism with the counting of the timer-counter. A signal detector connected to the filter indicates the presence of a pair of signal tones passing through the filter as it is slewed. Decoding means are connected to the counter-timer and the signal detector for generating a binary signal indicating the frequency of the bandpass filter which passes each signal tone. The binary signal is entered in a data register, and an interrupt posted to a host computer.

Abstract: A communication system includes a plurality of station sets each connected over two pair communication facilities to a control module. An adapter unit switchably connects an external data or voice device via a station set to either facility in response to a control signal from the control module. A data mode is established by sending a data mode request signal from the station set to the control module. An off-hook signal from a connected data device is used to request a data call. The control module signals to which facility the adapter is to connect the data call and outputs a unique visual on the data call facility. The control module prevents other calls from bridging onto or interfering with the data call. The system also permits a voice call on a facility to be converted to a data call on the other facility. Furthermore, a user can make a voice call over one facility while a data call is in progress on the other facility.

Abstract: The switching matrix comprises two data bus each one with n channels for conveying video signals, one address bus, control conductors and an array of N switching points; each of said switching points has two output switches, two input switches, one circuit receiving address signals to select on each data bus a channel corresponding to the received address, one circuit receiving control signals designed to validate either the pair formed by the first output switch and the second input switch, or the pair formed by the second output switch and the first input switch, to validate the setting up of a connection between the video transmitting means of the associated subscriber terminal and the selected channel.

Abstract: A circuit (16) is designed to prevent unauthorized access to a remote device such as a computer (10) over a communications system such as a telephone network (12). A remote computer terminal (13) is connected to the telephone network (12) through a conventional modem (14). At the remote location of computer (10), circuit (16) is connected between computer (10) and another modem (15). Circuit (16) is also connected to the telephone network (12) to receive a signal therefrom which connects modem (15) through circuit (16) to computer (10) to temporarily access the same. The connection, however, is disconnected after a predetermined time period unless circuit (16) receives a second signal from the telephone network (12) before the expiration of that predetermined time period.

Abstract: A system for transmitting and accessing data through a standard telephone system. The system including activating a key or sequence of keys wherein each key represents a plurality of letters. Signals produced by activating the keys are compared to a data base having indexed entries of words or names. In this way, words can be input into the system using only 8 unique keys.