NT1
Network termination 1 device. The device that provides an interface between the ISDN Basic Rate Interface (BRI) line used by the telephone company and a customers terminal equipment. The NT1 also provides power for the terminal equipment, if necessary. In North America, where ISDN BRI is a U loop, the customer must supply the NT1 device; in Japan and the European countries where BRI is an S/T bus, the telephone company supplies the NT1. The PortMaster integrates the NT1 device into its ISDN BRI ports that are U interfaces.