ISDN BRI is a standard service provided by the Integrated Services Digital Network (ISDN). BRI stands for Basic Rate Interface. ISDN BRI was developed for Internet connections used in small businesses and homes. This service is popular in most European countries, and is relatively accepted in certain parts of America.

ISDN BRI has unique and convenient features. This digital service can enable the simultaneous sending and receiving of any digital signal, may it be video, voice, or data. The 64 Kbps digital channels of ISDN BRI enable it to perform the said function. Through the ISDN Terminal Adapters, individuals can also create direct connections to and from telephones and data terminals. Another feature of ISDN BRI is its ability to connect to non-ISDN devices and achieve translation for the said equipment. This is done through its terminal adapters as well.

To carry out its functions, ISDN BRI makes use of certain channels. The following are the Bearer Channel or the B Channel to transmit data such as voice output, and the D Channel for control and signaling. D Channels can also transmit data.

ISDN BRI is also known as 2B+D. This is because it consists of 2 B Channels with a speed of 64 Kbps, and 1 D Channel with a speed of 16 Kbps. Since ISDN BRI has 2 64 Kbps B Channels, it has a 128 Kbps maximum data rate.