Integrated Services Digital Network

ISDN ISDNISDN30D-channelDigital Networkshigh speed connectionIntegrated Service Digital NetworkIntegrated Services Digital Network (ISDN)ISDN (data) phone linesISDN2e
Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network.wikipedia
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Basic Rate Interface

BRI2B1DBasic Rate (BRI)
The ISDN standards define several kinds of access interfaces, such as Basic Rate Interface (BRI), Primary Rate Interface (PRI), Narrowband ISDN (N-ISDN), and Broadband ISDN (B-ISDN).
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.

Plain old telephone service

POTSLocal Telephone Servicetelephone
The key feature of ISDN is that it integrates speech and data on the same lines, adding features that were not available in the classic telephone system.
POTS was the standard service offering from telephone companies from 1876 until 1988 in the United States when the Integrated Services Digital Network (ISDN) Basic Rate Interface (BRI) was introduced, followed by cellular telephone systems, and voice over IP (VoIP).

Primary Rate Interface

PRIprimary ratePRA or PRI
The ISDN standards define several kinds of access interfaces, such as Basic Rate Interface (BRI), Primary Rate Interface (PRI), Narrowband ISDN (N-ISDN), and Broadband ISDN (B-ISDN).
The Primary Rate Interface (PRI) is a telecommunications interface standard used on an Integrated Services Digital Network (ISDN) for carrying multiple DS0 voice and data transmissions between the network and a user.

Q.931

ITU-T Q.931
In common use, ISDN is often limited to usage to Q.931 and related protocols, which are a set of signaling protocols establishing and breaking circuit-switched connections, and for advanced calling features for the user.
ITU-T Recommendation Q.931 is the ITU standard ISDN connection control signalling protocol, forming part of Digital Subscriber Signalling System No. 1.

Terminal adapter

terminal adaptors
The T interface is a serial interface between a computing device and a terminal adapter, which is the digital equivalent of a modem.
In ISDN terminology, the terminal adapter connects a terminal (computer) to the ISDN network.

U interface

UU k0 U K0 -Interface
The U interface is a two-wire interface between the exchange and a network terminating unit, which is usually the demarcation point in non-North American networks.
The U interface or U reference point is a Basic Rate Interface (BRI) in the local loop of an Integrated Services Digital Network (ISDN).

Network termination 1

NT1network termination type 1network terminator
The S interface is a four-wire bus that ISDN consumer devices plug into; the S & T reference points are commonly implemented as a single interface labeled 'S/T' on a Network termination 1 (NT1).
Network Termination 1 (NT1) or Network Termination type 1 refers to equipment in an Integrated Services Digital Network (ISDN) that physically and electrically terminates the network at the customer's premises.

Frame Relay

Frame-RelayframesLAPF
In theory, Frame Relay can operate over the D channel of BRIs and PRIs, but it is seldom, if ever, used.
Originally designed for transport across Integrated Services Digital Network (ISDN) infrastructure, it may be used today in the context of many other network interfaces.

X.25

X25CCITT X.25 recommendationISO/IEC 8208
X.25 can be carried over the B or D channels of a BRI line, and over the B channels of a PRI line.
An X.25 WAN consists of packet-switching exchange (PSE) nodes as the networking hardware, and leased lines, plain old telephone service connections, or ISDN connections as physical links.

Circuit switching

circuit switchedcircuit-switchedcircuit mode
ISDN is a circuit-switched telephone network system, which also provides access to packet switched networks, designed to allow digital transmission of voice and data over ordinary telephone copper wires, resulting in potentially better voice quality than an analog phone can provide.
ISDN is one such service that uses a separate signalling channel while plain old telephone service (POTS) does not.

S interface

SS 0 -busS0
The S interface is a four-wire bus that ISDN consumer devices plug into; the S & T reference points are commonly implemented as a single interface labeled 'S/T' on a Network termination 1 (NT1).
The S interface or S reference point, also known as S 0, is a user–network interface reference point for basic rate access in an Integrated Services Digital Network (ISDN) environment, that

D channel

data (D) channel
In North America, Non-Facility Associated Signalling allows two or more PRIs to be controlled by a single D channel, and is sometimes called "23B+D + n*24B".
D channel (delta channel) is a telecommunications term which refers to the ISDN channel in which the control and signalling information is carried.

R interface

The R interface defines the point between a non-ISDN device and a terminal adapter (TA) which provides translation to and from such a device.
R interface or R reference point defines the point between a non-ISDN device and a terminal adapter (TA) which provides translation to and from such a device.

Business telephone system

PBXprivate branch exchangekey telephone system
PRI-ISDN is popular throughout the world, especially for connecting private branch exchanges to the public network.
The modern key system now supports SIP, ISDN, analog handsets (in addition to its own proprietary handsets - usually digital) as well as a raft of features more traditionally found on larger PBX systems.

ITU-T

CCITTTelecommunication Standardization SectorComité Consultatif International Téléphonique et Télégraphique
It was first defined in 1988 in the CCITT red book.
ISDN and PSTN/3G videoconferencing systems, H.320 and H.324

Fax

fax machinefacsimilefax machines
Integrated services refers to ISDN's ability to deliver at minimum two simultaneous connections, in any combination of data, voice, video, and fax, over a single line.
Personal computers have also long been able to handle incoming and outgoing faxes using analog modems or ISDN, eliminating the need for a stand-alone fax machine.

Internet access

broadband internetbroadbandbroadband Internet access
In some countries, ISDN found major market application for Internet access, in which ISDN typically provides a maximum of 128 kbit/s bandwidth in both upstream and downstream directions.
Integrated Services Digital Network (ISDN) is a switched telephone service capable of transporting voice and digital data, as well as one of the oldest Internet access methods.

Videotelephony

videoconferencingvideo conferencingvideo chat
Integrated services refers to ISDN's ability to deliver at minimum two simultaneous connections, in any combination of data, voice, video, and fax, over a single line. In a videoconference, ISDN provides simultaneous voice, video, and text transmission between individual desktop videoconferencing systems and group (room) videoconferencing systems.
Only in the late 20th century with the advent of powerful video codecs combined with high-speed Internet broadband and ISDN service did videotelephony become a practical technology for regular use.

Local loop

subscriber lineloopsubscriber loop
Integrated services refers to ISDN's ability to deliver at minimum two simultaneous connections, in any combination of data, voice, video, and fax, over a single line.
Integrated Services Digital Network (ISDN)

Public switched telephone network

PSTNtelephone networkpublic telephone network
PRI-ISDN is popular throughout the world, especially for connecting private branch exchanges to the public network. Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network.
However, digital technologies such as DSL, ISDN, FTTx, and cable modems have become more common in this portion of the network.

Non-Facility Associated Signalling

In North America, Non-Facility Associated Signalling allows two or more PRIs to be controlled by a single D channel, and is sometimes called "23B+D + n*24B".
When a T1 circuit is used to carry Primary Rate ISDN one of the timeslots is used to carry the D channel.

Signalling System No. 7

SS7SS7 NetworkCCS7
Between telephone company switches, the signaling is performed via SS7.
The Telephone User Part (TUP) was adopted in Europe and the Integrated Services Digital Network (ISDN) User Part (ISUP) adapted for public switched telephone network (PSTN) calls was adopted in North America.

BT Highway

Home Highway and Business Highway
Until April 2006, they also offered services named Home Highway and Business Highway, which were BRI ISDN-based services that offered integrated analogue connectivity as well as ISDN.
BT Highway was a UK retail ISDN2e service from British Telecom which was announced in November 1997 and withdrawn in February 2007.

Telephone network

Network engineeringtelephonefixed and mobile networks
ISDN is a circuit-switched telephone network system, which also provides access to packet switched networks, designed to allow digital transmission of voice and data over ordinary telephone copper wires, resulting in potentially better voice quality than an analog phone can provide.
Integrated Services Digital Network (ISDN)

Comrex

Use of IP-based streaming codecs such as Comrex ACCESS and ipDTL is becoming more widespread in the broadcast sector, using broadband internet to connect remote studios.
From 1991 to 2000, Comrex released a series of ISDN codecs.