A T-interface or T reference point is used for basic rate access in an Integrated Services Digital Network (ISDN) environment. It is a User–network interface reference point that is characterized by a four-wire, 144 kbit/s (2B+D) user rate.
Other characteristics of a T-interface are: it accommodates the link access and transport layer function in the ISDN architecture it is located at the user premises it is distance sensitive to the servicing Network termination 1 it functions in a manner similar to that of the Channel service units (CSUs) and the Data service units (DSUs).
The T interface is electrically equivalent to the S interface, and the two are jointly referred to as the S/T interface.
See also R interface S interface U interface
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