Network Terminator One
Device for Basic Rate ISDN (
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 multiple four-wire connections, for example, one for a telephone and one for a fax machine. The NT1 is physically connected between the ISDN board of a
videoconferencing system and the ISDN
phone line. The NT1 supports network
maintenance functions such as
loop testing.