U INTERFACE

For basic-rate access in an Integrated Services Digital Network ( ISDN ) environment, a user -to- network interface reference point that is characterized by the use of a 2-wire- loop transmission system that (a) conveys information between the 4-wire user-to-network interface, i.e., the S/ T reference point , and the local exchange , (b) is located in the servicing central office , and (c) is not as distance sensitive as a service using a T interface.