An Integrated Services Digital Network (ISDN) configuration defined in the physical layer standard I.430 produced by the ITU. It is one of two configurations for use in the access network, the other being primary rate interface. The BRI configuration provides two 64 kbit/s "bearer" channels (B channels) and one 16 kbit/s "Delta" channel (D channel). The B channels are used for voice or user data, and the D channel is used for any combination of: data, control/signalling and X.25 packet networking. The two B channels can be bonded together giving a total data rate of 128 kbit/s. BRI is the kind of ISDN interface most likely to be found in residential service