Network Termination 1. The termination point of the ISDN system. It is the physical and electrical termination function of ISDN on the end-user's side of the ISDN connection. Without an NT1, ISDN cannot work. It is an interface between the S/T and U reference points and defines communication between functional devices.

network termination 1. In ISDN, an end point for the network's transmission line. Network termination 1 is responsible for the physical layer characteristics (of the OSI reference model), such as ending the line transmission, monitoring performance, and timing. See also network termination 2 (NT2), terminal equipment 1 (TE1), and terminal equipment 2 (TE2).

Network Terminator Type 1 The NT-1 is physically connected between the ISDN board of your videoconferencing system and your ISDN phone line and converts the two-wire line coming from your telephone company into a 4-wire line. And provides network maintenance functions such line maintenance access, timing, and echo cancellation. NT1s may be built into other pieces of equipment or stand alone.

(network terminator one) is a device for BRI that converts the two off-premises signal wires to four-wire connections suitable for an ISDN telephone. An NT1 is often designed to support more than one of these four-wire connections, for example, one for a telephone and one for a fax machine.