Integrated Services Digital Network (ISDN)
Basic Rate Interface (BRI)


ISDN BRI is a telecommunications standard specified by the International Telecommunication Union (ITU) that provides an all-digital, switched connection to support voice and data services.

ISDN BRI integrates service by allowing users to perform several digital functions at one time. ISDN BRI customers can research pertinent data on the Internet while participating in a conference call, fax important documents while e-mailing the recipients and send large digital files (graphics or text) in a fraction of the time it would take with regular dial-up. All of this is accomplished with ordinary copper phone lines and an ISDN BRI card.



  • Help Increase Productivity. Using ISDN BRI’s higher speeds—ISDN BRI utilizes two separate 64 Kbps channels that can be combined into one 128 Kbps channel.
  • Faster Data Transmission Speeds. Result in quick connection times and low usage costs.
  • Avoid Costs and Inflexibility of Dedicated Lines. The same ISDN line can be used to carry both voice and data, so there is no need to wait for a fax to finish before making a call.
  • Productivity-Enhancing Applications. Take advantage of these applications, such as remote Local Area Network (LAN) access, videoconferencing, pre-press graphics, postproduction editing and digital broadcasting that can reduce travel costs and product development time.
  • Clear, Digital Transmission. This results in few errors or re-transmissions and provides a highly reliable network– all of which can help increase productivity.
  • Back Up Overflow-Dedicated Services. ISDN can be used to protect against outages or to provide cost effective insurance against high-volume congestion for mission critical information. In a large government office, ISDN may be provisioned for use as a disaster recovery backup.



ISDN BRI is a two-wire digital subscriber line that provides the following features:

  • Two 64 Kbps bearer (B) channels used for voice, data, and video; both B channels can be bonded providing a 128Kbps circuit.
  • One 16 Kbps data (D) channel used as the signaling channel for call set-up and call-completion messages to support enhanced features such as caller ID and to carry low-bandwidth, packet-switched data.

Verizon supports both national (standard) and custom ISDN, though national is promoted and preferred. National ISDN is standards-based and supported by all switch suppliers to ensure switch interoperability.

ISDN BRI lines are supported per the specifications found in ANSI/EIA T1.607 and 610. ISDN BRI lines can consist of one or two B channels of 64 Kbps each and one D channel of 16 Kbps.