Primary rate interface
Encyclopedia
The Primary Rate Interface (PRI) is a standardized telecommunication
s service level within the Integrated Services Digital Network
(ISDN) specification for carrying multiple DS0 voice and data transmissions between a network and a user.
PRI is the standard for providing telecommunication services to offices. It is based on the T-carrier
(T1) line in the US and Canada, and the E-carrier
(E1) line in Europe. The T1 line consists of 24 channels, while an E1 has 31.
s (bearer channels)) and 1xD (D channel
(data channel)) (23 64-kbit/s digital channels + 1 64-kbit/s signaling/control channel) on a T1 (1.544 Mbit/s). In Europe and Australia it is 30xB + 1xD on an E1 2.048 Mbit/s. One timeslot on the E1 is used for synchronization purposes and is not considered to be a B or D channel.
(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. Both rates include a number of B-channels and a D-channel. Each B-channel carries data, voice, and other services. The D-channel carries control and signaling information. The Basic Rate Interface consists of two 64-kbit/s B-channels and one 16-kbit/s D-channel.
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.
Larger connections are possible using PRI pairing. A dual PRI could have 24+23= 47 B-channels and 1 D-channel (often called "47B + D"), but more commonly has 46 B-channels and 2 D-channels thus providing a backup signaling channel. The concept applies to E1s as well and both can include more than 2 PRIs. Normally, no more than 2 D-channels are provisioned as additional PRIs are added to the group.
(PSTN). The 23 (or 30) B-channels can be used flexibly and reassigned when necessary to meet special needs such as video conferences. The Primary Rate user is hooked up directly to the telephone company central office.
primary-5ess Lucent 5ESS switch type for the U.S.
primary-dms100 Northern Telecom DMS-100 switch type for the U.S.
primary-dpnss DPNSS switch type for Europe
primary-net5 NET5 switch type for UK, Europe, Asia and Australia
primary-ni National ISDN Switch type for the U.S.
primary-ni2c The Cisco NAS-SC switchtype based on NI2C
primary-qsig QSIG switch type
primary-ts014 TS014 switch type for Australia (obsolete)
primary 30 Channels
Telecommunication
Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...
s service level within the Integrated Services Digital Network
Integrated Services Digital Network
Integrated Services Digital Network is a set of communications standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network...
(ISDN) specification for carrying multiple DS0 voice and data transmissions between a network and a user.
PRI is the standard for providing telecommunication services to offices. It is based on the T-carrier
T-carrier
In telecommunications, T-carrier, sometimes abbreviated as T-CXR, is the generic designator for any of several digitally multiplexed telecommunications carrier systems originally developed by Bell Labs and used in North America, Japan, and South Korea....
(T1) line in the US and Canada, and the E-carrier
E-carrier
In digital telecommunications, where a single physical wire pair can be used to carry many simultaneous voice conversations by time-division multiplexing, worldwide standards have been created and deployed...
(E1) line in Europe. The T1 line consists of 24 channels, while an E1 has 31.
T1 and E1 systems
PRI provides a varying number of channels depending on the standards in the country of implementation. In North America and Japan it consists of 23xB (B channelB channel
B channel is a telecommunications term which refers to the ISDN channel in which the primary data or voice communication is carried. It has a bit rate of 64 kbit/s in full duplex....
s (bearer channels)) and 1xD (D channel
D channel
D channel is a telecommunications term which refers to the ISDN channel in which the control and signalling information is carried.The bit rate of the D channel of a basic rate interface is 16 kbit/s, whereas it amounts to 64 kbit/s on a primary rate interface.For DSS1 signalling, the D channel...
(data channel)) (23 64-kbit/s digital channels + 1 64-kbit/s signaling/control channel) on a T1 (1.544 Mbit/s). In Europe and Australia it is 30xB + 1xD on an E1 2.048 Mbit/s. One timeslot on the E1 is used for synchronization purposes and is not considered to be a B or D channel.
PRI and BRI
The Integrated Services Digital NetworkIntegrated Services Digital Network
Integrated Services Digital Network is a set of communications standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network...
(ISDN) prescribes two levels of service, the Basic Rate Interface
Basic rate interface
Basic Rate Interface is an Integrated Services Digital Network configuration intended primarily for use in subscriber lines similar to those that have long been used for plain old telephone service...
(BRI), intended for the homes and small enterprises, and the Primary Rate Interface (PRI), for larger applications. Both rates include a number of B-channels and a D-channel. Each B-channel carries data, voice, and other services. The D-channel carries control and signaling information. The Basic Rate Interface consists of two 64-kbit/s B-channels and one 16-kbit/s D-channel.
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.
Larger connections are possible using PRI pairing. A dual PRI could have 24+23= 47 B-channels and 1 D-channel (often called "47B + D"), but more commonly has 46 B-channels and 2 D-channels thus providing a backup signaling channel. The concept applies to E1s as well and both can include more than 2 PRIs. Normally, no more than 2 D-channels are provisioned as additional PRIs are added to the group.
Fractional T1
Fewer active B channels (also called bearer channels) can be used for a fractional T1. Bearer channels may also be known as user channels. More channels can be used with more T1s, within certain design limits.Application
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 NetworkPublic switched telephone network
The public switched telephone network is the network of the world's public circuit-switched telephone networks. It consists of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all inter-connected by...
(PSTN). The 23 (or 30) B-channels can be used flexibly and reassigned when necessary to meet special needs such as video conferences. The Primary Rate user is hooked up directly to the telephone company central office.
ISDN PRI variants (switch types)
primary-4ess Lucent 4ESS switch type for the U.S.primary-5ess Lucent 5ESS switch type for the U.S.
primary-dms100 Northern Telecom DMS-100 switch type for the U.S.
primary-dpnss DPNSS switch type for Europe
primary-net5 NET5 switch type for UK, Europe, Asia and Australia
primary-ni National ISDN Switch type for the U.S.
primary-ni2c The Cisco NAS-SC switchtype based on NI2C
primary-qsig QSIG switch type
primary-ts014 TS014 switch type for Australia (obsolete)
primary 30 Channels
See also
- Non-Facility Associated SignallingNon-Facility Associated SignallingNon-Facility Associated Signalling or NFAS is a Primary Rate Interface configuration whereby multiple T1 carriers share a signaling channel ....
- H-channelH-channelIn the Integrated Services Digital Network , a high-speed channel comprising multiple aggregated low-speed channels to accommodate bandwidth-intensive applications such as file transfer, videoconferencing, and high-quality audio...
- D channelD channelD channel is a telecommunications term which refers to the ISDN channel in which the control and signalling information is carried.The bit rate of the D channel of a basic rate interface is 16 kbit/s, whereas it amounts to 64 kbit/s on a primary rate interface.For DSS1 signalling, the D channel...
- B channelB channelB channel is a telecommunications term which refers to the ISDN channel in which the primary data or voice communication is carried. It has a bit rate of 64 kbit/s in full duplex....
- Caller ID spoofingCaller ID spoofingCaller ID spoofing is the practice of causing the telephone network to display a number on the recipient's Caller ID display that is not that of the actual originating station. The term is commonly used to describe situations in which the motivation is considered malicious by the speaker or writer...