Basic Rate Interface


Basic Rate Interface or Basic Rate Access is an Integrated Services Digital Network configuration intended primarily for use in subscriber lines similar to those that have long been used for voice-grade telephone service.
As such, an ISDN BRI connection can use the existing telephone infrastructure at a business.
The BRI configuration provides 2 data channels at 64 kbit/s each and 1 control channel at 16 kbit/s. The B channels are used for voice or user data, and the D channel is used for any combination of data, control/signaling, and X.25 packet networking. The 2 B channels can be aggregated by channel bonding providing a total data rate of 128 kbit/s. The BRI ISDN service is commonly installed for residential or small business service in many countries.
In contrast to the BRI, the Primary Rate Interface configuration provides more B channels and operates at a higher bit rate.

Physical interfaces

The BRI is split in two sections:
a) in-house cabling from the ISDN terminal up to the network termination 1 and
b) transmission from the NT1 to the central office.