Interface between the network termination NT (on the customer's site) and the line termination LT (at the public exchange). The main line codes used at the ISDN BRA U interfaces are : 2B1Q and 4B3T.
The two wire ISDN interface method. See also S/T interface, and NT-1
Edit / The electrical interface between an ISDN telephone line and a network terminator (NT1) device. See Also: BRI DSL PSTN