Nortel 25UMM00751JAG (telecommunications transmission and networking portfolio) Telecom System Card / Module

The Nortel 25UMM00751JAG is an LECO2 PDMX line card delivering a 2Mbit/s (E1) HDSL circuit at 75-ohm impedance, decoded directly from its own part label. HDSL (High-bit-rate Digital Subscriber Line) equipment of this type extends full E1-rate digital service over ordinary copper pairs beyond the reach of standard leased-line repeaters, and cards in the LECO/PDMX family sit in Nortel’s access-network transmission shelves alongside other E1 line and multiplexer cards. The 75-ohm variant is built for coaxial E1 distribution rather than the 120-ohm balanced-pair alternative, so it should not be substituted into a 120-ohm shelf without confirming impedance compatibility. Cards of this generation remain in service on legacy copper access networks where fibre has not yet been run, and genuine spares are a routine requirement for operators maintaining that footprint. Specifiers should confirm the exact host shelf and impedance requirement against their installation before ordering. Tech-Star (UK-based, shipped worldwide) stocks Nortel access transmission cards to support ongoing network maintenance projects.