For the French television channel, see NT1 (television channel).
TR1 is a network termination that separates the public from the private network into ISDN. In English NT1 of Net Terminal 1. There are two types, the normal ones with only digital outputs and the mixed ones, also with an integrated terminal adapter for analog outputs. another definition is: Network Termination Equipment 1 (TR1): It is used to connect the user equipment to the local loop of transmission that connects it to the external switching center of the ISDN, in other words, it is the element that allows the interconnection between the indoor installation of the user to 4 wires, and the external network, to 2 wires. it should be noted that these NT1 are modems, which are used in BRI (Basic Rate Interface) services which handles 2 64k channels, which together can form a 128k service, these modems are "U" type interface (a copper pair) to the public network and ST (RJ45) or analog interfaces (conventional telephone lines, RJ11) to the user
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