Power and backup power considerations for the ISDN network termination 1 (NT1)

The evolution to a narrowband integrated services digital network (ISDN) necessitates the installation of additional electronics at the user end of the loop. Providing power and backup power for these electronics (referred to as the network termination 1 (NT1)) offers challenges to designers. One problem is that reliability and backup powering are not currently addressed in a uniform manner in the US. For locally provided power, the authors propose baseline criteria for reliability and backup powering. One generic topology comprising a power supply, a battery charger, and secondary batteries is presented. A backup time of eight hours is proposed with an option for additional backup provided via an extended reserve cabinet using primary or secondary batteries.<>