Nortel NTBK22AA (telecommunications transmission and networking portfolio) Telecom System Card / Module

The Nortel NTBK22AA is a BRI (Basic Rate ISDN) Signalling Processor for Meridian 1 Option 11 systems, referred to in Nortel’s own documentation by the SISP (Signalling ISDN Signalling Processor) designation. It handles the D-channel call-control signalling for ISDN BRI circuits on the smaller Option 11 chassis, working alongside the platform’s BRI line cards to process call setup, teardown and feature signalling centrally rather than per line card, the direct Option 11-chassis equivalent of the NT6D73AA signalling processor built for the larger Option 51-81 range. Option 11 was Nortel’s compact Meridian 1 chassis aimed at smaller sites, and BRI signalling processors of this kind supported ISDN-based station equipment or BRI trunk connections on those systems. A number of Option 11 installations using BRI remain in service, particularly smaller UK businesses that adopted ISDN for either trunking or specific ISDN-capable terminal equipment. Tech-Star (UK-based, shipped worldwide) supplies Meridian 1 Option 11 signalling processors for ongoing PBX maintenance.