DPNSS was developed in the early 1980s by BT, or its forerunner, Post Office Telecommunications in recognition that the emerging Digital Private Circuit Primary Rate product ' Megastream ' had to address the market for both data and voice, the latter being significantly greater because of the market for PBXs.

There are several kinds of access interfaces to ISDN defined as Basic Rate Interface ( BRI ), Primary Rate Interface ( PRI ) and Broadband ISDN ( B-ISDN ).

The other ISDN access available is the Primary Rate Interface ( PRI ), which is carried over an E1 ( 2048 kbit / s ) in most parts of the world.

Primary Rate Interface ( PRI ), also called primary rate access ( PRA ) in Europe — contains a greater number of B channels and a D channel with a bandwidth of 64 kbit / s.

The following is an example of a Primary Rate ( PRI ) ISDN call showing the Q. 921 / LAPD and the Q. 931 / Network message intermixed ( i. e. exactly what was exchanged on the D-channel ).

The Primary Rate Interface ( PRI ) is a standardized telecommunications service level within the Integrated Services Digital Network ( ISDN ) specification for carrying multiple DS0 voice and data transmissions between a network and a user.

The Integrated Services Digital Network ( ISDN ) prescribes two levels of service, the Basic Rate Interface ( BRI ), intended for the homes and small enterprises, and the Primary Rate Interface ( PRI ), for larger applications.

The Primary Rate Interface ( PRI ) consists of 23 64-kbit / s B-channels and one 64-kbit / s D-channel using a T1 line, often referred to as " 23B + D ", ( North American and Japanese standard ) or 30 B-channels and one D-channel using an E1 line ( Europe / rest of world ).

A T1 Primary Rate Interface user would have access to a 1. 472-Mbit / s data service.

An E1 Primary Rate Interface user would have access to a 1. 920 Mbit / s data service

The Primary Rate Interface channels are typically used by medium to large enterprises with digital PBXs to provide them digital access to the Public Switched Telephone Network ( PSTN ).

The Primary Rate user is hooked up directly to the telephone company central office.

fr: Primary Rate Interface

pl: Primary Rate Interface

In contrast to the BRI, the Primary Rate Interface ( PRI ) configuration provides more B channels and operates at a higher bit rate.

In the typical telephony environment, a PBX connects to the local service provider through Primary Rate Interface ( PRI ) trunks.

* Primary Rate Interface, telecommunication standard

Additionally, for voice T1s there are two main types: so-called " plain " or Inband T1s and PRI ( Primary Rate Interface ).

Non-Facility Associated Signalling or NFAS is a Primary Rate Interface configuration whereby multiple T1 carriers share a signalling channel ( or D channel ).

When a T1 circuit is used to carry Primary Rate ISDN one of the timeslots is used to carry the D channel.

A single Primary Rate ISDN circuit is thus sometimes described as 23B + D. There are 23 bearer channels carrying voice or data, and one D channel carrying the Common Channel Signaling.

Customers ordering a Primary Rate ISDN service will be charged for each signalling channel.

* Non-Facility Associated Signalling, a Primary Rate Interface configuration whereby multiple T1 carriers share a signaling channel ( or D channel ).

Primary research articles are published in the sister journals Proceedings of the Royal Society, Biology Letters, Journal of the Royal Society Interface, and Interface Focus.

The entry level interface to ISDN is the Basic ( s ) Rate Interface ( BRI ), a 128 kbit / s service delivered over a pair of standard telephone copper wires.

Basic Rate Interface ( BRI ), also called basic rate access ( BRA ) — consists of two B channels, each with bandwidth of 64 kbit / s, and one D channel with a bandwidth of 16 kbit / s.

Consumer-oriented ADSL was designed to operate on existing lines already conditioned for Basic Rate Interface ISDN services, which itself is a switched digital service ( non-IP ), though most incumbent local exchange carriers ( ILECs ) provision Rate-Adaptive Digital Subscriber Line ( RADSL ) to work on virtually any available copper pair facility — whether conditioned for BRI or not.

The Basic Rate Interface consists of two 64-kbit / s B-channels and one 16-kbit / s D-channel.

# REDIRECT Basic Rate Interface

Basic Rate Interface ( BRI, 2B + D, 2B1D ) is an Integrated Services Digital Network ( ISDN ) configuration intended primarily for use in subscriber lines similar to those that have long been used for plain old telephone service.