Standardized connection to a ISDN network giving a data rate of 144 kbit/s: two 64 kbit/s B channels and one 16 bit/s D channel. The B channel, switched to circuit mode, is used for the routing of all types of information. Channel D carries signaling or data in packet mode. The interface is called T0.

In English, we talk about BRI: Basic Rate Interface = basic access to the ISDN.