Abstract: A system for supervising a telephone connection using over a pulse code modulated carrier network between a first customer's equipment and a second customer's equipment. A first channel unit is located in a channel bank serving the first customer's telephone equipment. A second channel unit is located in a channel bank at a remote central office that is geographically remote from the first customer's equipment. The second channel unit is coupled to the second customer's equipment through a switch at the remote Central Office. The second channel unit includes a means for detecting a reverse battery signal generated by the Central Office when the second customer's telephone goes off-hook, and a means for converting the reverse battery signal into a digital supervisory signal. The second channel unit transmits the digital supervisory signal, preferably using the A and B signalling bits on a pulse code modulated carrier system.

Abstract: A two-way broadband audio telephone communications system using 2B1Q line coding between a program amplifier located at a remote site and the central office. The program amplifier includes a codec to convert analog audio signals to digital data at a predetermined sampling rate, and a 2B1Q transceiver to convert the digital data into 2B1Q signals. The program amplifier communicates with a channel unit in the central office channel bank over a conventional two-wire link. This channel unit includes a 2B1Q transceiver that translates the 2B1Q signals received from the program amplifier into PCM format compatible with the T1 carrier system. In order to provide wide bandwidth, the channel unit is allocated at least two channels in each T1 frame. The central office channel bank can communicate with any other similarly equipped channel bank over the T1 carrier.

Abstract: A system for testing 2B1Q private line data telephony circuits having 2B1Q modulation between the network channel termination equipment and the channel unit. 2B1Q modulation is provided over a single pair of wires connected to the E and M leads of the channel unit. The system can deliver testing signals from two different sources. The first source is from a remote testing system connected to a remote access system which in turn is connected to the T, T1, R, and R1 output leads of the channel unit. The remote testing system generates conventional testing signals which are converted into digital signals for directly communicating with the 2B1Q pair of wires. The remote testing system delivers conventional tests for testing the loopback of the channel connected to the single pair of wires and to the network channel termination equipment. Under a second source of tests, the interface of the present invention directly connects to the T1 carrier.

Abstract: A sealing current generator for a telephone circuit provides a conventional nominal DC bias current in a telephone loop, and also temporarily provides a higher "zap" current whenever the DC current path is broken and then reapplied to the telephone loop. During the "zap" period, the voltage placed across the telephone loop is progressively increased in a number of predetermined steps if the current actually measured in the telephone loop fails to exceed a minimum value. The voltage is then maintained at its last level for the remainder of the "zap" period, after which the device returns to its base mode of providing a nominal DC bias current to the telephone loop.

Abstract: A smart data station termination ("DST") uses a method for remote alignment in which the switched access remote test system ("SARTS") sends a test tone of a single, predetermined frequency and power level to the receive-in port of the DST. The DST amplifies this test tone by a fixed gain factor (e.g. 4 dB) and then progressively increases attenuation (e.g. by 0.1 dB increments) of said amplified test tone until the resulting signal supplied to the receive-out port of the DST is reduced to a predetermined power level (i.e. -16 dBm). After alignment, the attenuation factor remains constant during normal operation of the DST. The preferred embodiment also provides a transponder mode of operation in which test signals received from the SARTS through the receive-in port of the DST are routed through an automatic gain control ("AGC") amplifier and transmitted back to the SARTS at a substantially constant level through the transmit-out port of the DST.