Cisco NM-8B-S/T enterprise networking (router/Catalyst switch/UCS families) Router Line Card

The Cisco NM-8B-S/T is an 8-port ISDN BRI network module for Cisco’s 2600, 3600 and 3700 series modular routers, providing eight S/T-interface Basic Rate ISDN ports (2B+D each) from a single network-module bay. It was used for dial-backup, dial-on-demand routing and remote-access aggregation applications where a branch or head-office router needed multiple ISDN lines rather than a single BRI WIC, such as aggregating dial-in connections from several remote sites onto one router. The S/T interface variant connects to an NT1 (network termination) device rather than directly to the line, distinguishing it from the U-interface version used in regions where the NT1 function is built into the router. These routers remain in service in a number of established legacy WAN deployments, and a genuine spare such as this restores ISDN capacity after a module failure. Tech-Star (UK-based, shipped worldwide) stocks Cisco network modules for engineers maintaining these platforms.