Abstract: An enhanced ISDN-DP transmission device of the present invention allows for testing of ISDN-protocol communication paths using an existing DDS-protocol test infrastructure. The ISDN-DP unit receives a DDS test command and determines whether the command was intended for the immediate receiving unit or a tandem unit. If the command is intended for the immediate ISDN-DP unit, the unit processes the command. If the command is intended for another ISDN device in the transmission path, the ISDN-DP converts the DDS-protocol command to an ISDN-protocol command and transmits the converted ISDN command to an adjacent tandem ISDN device in the communication path in an upstream or downstream direction. After the test path is enabled, loopback testing is available on all available ISDN bandwidth, including the B1, B2 and D+ channels, from a DDS-protocol test set.

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: A system for isolating the direction of communication errors in the local loop of a digital data network is described. A Network Interface Unit (NIU) located at the customer premises typically has a loopback feature, allowing for Bit Error Rate Tests (BERT) to be performed on the local loop from a remote test system located on the data network. The NIU loopback test isolates transmission problems at the customer premises from problems on the local loop. The present invention adds test pattern generation capability to the NIU, allowing the remote test system to determine whether the transmission problem on the local loop is in the network to customer premises direction or in the customer premises to network direction.

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: Loop circuits lacking byte alignment are tested by test equipment signals at 9.6 kbps transmitted over a DS.phi. format 19.2 kbps communication network. Upon indication of loss of 19.2 kbps framing, return signals from the loop are reformatted into a 9.6 kbps format by selecting proper return bytes using a logic system stored in an office channel unit (OCU).

Abstract: In a digital communication system, select devices are capable of generating and detecting data sequences that are normally suppressed by end user equipment for establishing inband communications among the select devices. Select devices capable of participating in inband communications may include the controller, Digital Channel Units (CUs) and Customer Premises Equipment (CPEs). Inband communications is initiated by a select device by transmitting a sequence comprising a plurality of first bytes for preventing inadvertant initiation of maintenance operations for digital devices in a particular time slot, followed by a plurality of second bytes. Inband communications is established when the select device 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.