Abstract: In a time division multiplex digital communication system, access devices are capable of generating and detecting data sequences that are normally suppressed by end user equipment for establishing in-band communications between the access device and selected intelligent channel units (ICU's ). An ICU initiates in-band communication with the access device by transmitting a service request sequence to the access device. The access device transmits a wake-up sequence to the ICU to establish in-band communication. Once established, in-band communications can then be used to accomplish automated provisioning, performance reporting, status reporting, alarm reporting as well as other important functions.

Abstract: In a time division multiplex digital communication system, access devices are capable of generating and detecting data sequences that are normally suppressed by end user equipment for establishing in-band communications between the access device and selected intelligent channel units (ICU's). In-band communication is initiated by transmitting a sequence comprising a plurality of first bytes for preventing inadvertent initiation of maintenance operations for digital devices in a particular time slot, followed by a plurality of second bytes in said time slot. In-band communications is established when the selected ICU receives a sequence comprising a plurality of said first bytes, a plurality of bytes which identify the select device and a plurality of said second bytes. Once established, in-band communications can then be used to accomplish automated provisioning, performance reporting, status reporting, alarm reporting as well as other important functions.

Abstract: A line interface module and selected channel unit modules are replaced in a digital terminal which couples time multiplexed digital communications lines to a plurality of voice signal lines. The line interface unit is provided with means for responding to a controller to insert PCM data into selected time slots of the PCM signal on the digital line and to latch data received on the line. In addition to receiving pulse amplitude modulated signals from a receive unit in the terminal, voice channel units may also receive the PCM code. A state machine in the channel unit recognizes control sequences of insert data. By means of the insert data, the controller may direct provisioning of the channel unit with such adjustments as gain control and equalization. It may also direct the channel unit to switch to a loopback mode of operation for diagnostics. PCM corresponding to tones may also be inserted by the line interface unit to assist in diagnostics.