Basic Rate Interface (BRI, 2B+D, 2B1D) or Basic Rate Access is an Integrated Services Digital Network (ISDN) 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 (bearer) channels (B channels) at 64 kbit/s each and 1 control (delta) channel (D 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 (ISDN PABX) in many countries.
In contrast to the BRI, the Primary Rate Interface (PRI) configuration provides more B channels and operates at a higher bit rate.4BRI module applies to PLANET IPX-2200, IPX-2500v2, IPX-2500v1 and IPX-2100v1 IP PBX system with one port. This port has four LEDs (light-emitting diodes), which is assembled on the mainboard.