Integrated Services Digital Network

3/10/2015 Integrated Services Digital Network - Wikipedia, the free encyclopedia

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Integrated Services Digital NetworkFrom Wikipedia, the free encyclopedia

Integrated Services for Digital Network (ISDN) is a set of communication standards for simultaneousdigital transmission of voice, video, data, and other network services over the traditional circuits of the public

switched telephone network. It was first defined in 1988 in the CCITT red book.[1] Prior to ISDN, thetelephone system was viewed as a way to transport voice, with some special services available for data. Thekey feature of ISDN is that it integrates speech and data on the same lines, adding features that were notavailable in the classic telephone system. There are several kinds of access interfaces to ISDN defined as BasicRate Interface (BRI), Primary Rate Interface (PRI), Narrowband ISDN (N-ISDN), and Broadband ISDN (B-ISDN).

ISDN is a circuit-switched telephone network system, which also provides access to packet switchednetworks, 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. It offers circuit-switchedconnections (for either voice or data), and packet-switched connections (for data), in increments of 64 kilobit/s.A major market application for ISDN in some countries is Internet access, where ISDN typically provides amaximum of 128 kbit/s in both upstream and downstream directions. Channel bonding can achieve a greaterdata rate; typically the ISDN B-channels of three or four BRIs (six to eight 64 kbit/s channels) are bonded.

ISDN should not be mistaken for its use with a specific protocol, such as Q.931 whereas ISDN is employed asthe network, data-link and physical layers in the context of the OSI model. In a broad sense ISDN can beconsidered a suite of digital services existing on layers 1, 2, and 3 of the OSI model. ISDN is designed toprovide access to voice and data services simultaneously.

However, common use reduced ISDN to be limited to Q.931 and related protocols, which are a set ofprotocols for establishing and breaking circuit switched connections, and for advanced calling features for the

user. They were introduced in 1986.[2]

In a videoconference, ISDN provides simultaneous voice, video, and text transmission between individualdesktop videoconferencing systems and group (room) videoconferencing systems.

Contents

1 ISDN elements

2 Basic Rate Interface

3 Primary Rate Interface

4 Bearer channels

5 Signaling channel

6 X.25

7 Frame Relay

8 Consumer and industry perspectives

8.1 ISDN and broadcast industry

8.2 Countries

8.2.1 United States and Canada



8.2.2 India

8.2.3 Japan

8.2.4 United Kingdom

8.2.5 France

8.2.6 Germany

8.2.7 Greece

8.3 International deployment

9 Configurations

10 Reference points

11 Types of communications

12 Sample call

13 See also

13.1 Protocols

13.2 Other

14 Notes

15 References

16 External links

ISDN elements

Integrated services refers to ISDN's ability to deliver at minimum two simultaneous connections, in anycombination of data, voice, video, and fax, over a single line. Multiple devices can be attached to the line, andused as needed. That means an ISDN line can take care of most people's complete communications needs(apart from broadband Internet access and entertainment television) at a much higher transmission rate, without

forcing the purchase of multiple analog phone lines. It also refers to integrated switching and transmission[3] inthat telephone switching and carrier wave transmission are integrated rather than separate as in earliertechnology.

Basic Rate Interface

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.[4] The 144 kbit/s payload rate is broken down into two 64 kbit/s bearerchannels ('B' channels) and one 16 kbit/s signaling channel ('D' channel or data channel). This is sometimes

referred to as 2B+D.[5]

The interface specifies the following network interfaces:

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 T interface is a serial interface between a computing device and a terminal adapter, which is the

digital equivalent of a modem.

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 an Network termination 1 (NT1).

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.

BRI-ISDN is very popular in Europe but is much less common in North America. It is also common in Japan

where it is known as INS64.[6][7]

Primary Rate Interface

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. An E1 is 30 'B' channels of 64 kbit/s, one 'D' channel of 64 kbit/s and a timing andalarm channel of 64 kbit/s.

In North America PRI service is delivered on one or more T1 carriers (often referred to as 23B+D) of 1544kbit/s (24 channels). A PRI has 23 'B' channels and 1 'D' channel for signalling (Japan uses a circuit called a J1,which is similar to a T1). Inter-changeably but incorrectly, a PRI is referred to as T1 because it uses the T1carrier format. A true T1 (commonly called "Analog T1" to avoid confusion) uses 24 channels of 64 kbit/s of in-band signaling. Each channel uses 56 kb for data and voice and 8 kb for signaling and messaging. PRI uses outof band signaling which provides the 23 B channels with clear 64 kb for voice and data and one 64 kb 'D'channel for signaling and messaging. In North America, Non-Facility Associated Signalling allows two or morePRIs to be controlled by a single D channel, and is sometimes called "23B+D + n*24B". D-channel backupallows for a second D channel in case the primary fails. NFAS is commonly used on a T3.

PRI-ISDN is popular throughout the world, especially for connecting PBXs to PSTN.

While the North American PSTN can use PRI or Analog T1 format from PBX to PBX, the POTS or BRI canbe delivered to a business or residence. North American PSTN can connect from PBX to PBX via Analog T1,T3, PRI, OC3, etc...

Even though many network professionals use the term "ISDN" to refer to the lower-bandwidth BRI circuit, inNorth America BRI is relatively uncommon whilst PRI circuits serving PBXs are commonplace.

Bearer channels

The bearer channel (B) is a standard 64 kbit/s voice channel of 8 bits sampled at 8 kHz with G.711 encoding.B-Channels can also be used to carry data, since they are nothing more than digital channels.

Each one of these channels is known as a DS0.

Most B channels can carry a 64 kbit/s signal, but some were limited to 56K because they traveled over RBSlines. This was commonplace in the 20th century, but has since become less so.

Signaling channel

The signaling channel (D) uses Q.931 for signaling with the other side of the link.

X.25



X.25 can be carried over the B or D channels of a BRI line, and over the B channels of a PRI line. X.25 overthe D channel is used at many point-of-sale (credit card) terminals because it eliminates the modem setup, andbecause it connects to the central system over a B channel, thereby eliminating the need for modems and makingmuch better use of the central system's telephone lines.

X.25 was also part of an ISDN protocol called "Always On/Dynamic ISDN", or AO/DI. This allowed a user tohave a constant multi-link PPP connection to the internet over X.25 on the D channel, and brought up one ortwo B channels as needed.

Frame Relay

In theory, Frame Relay can operate over the D channel of BRIs and PRIs, but it is seldom, if ever, used.

Consumer and industry perspectives

There is a second viewpoint: that of the telephone industry, where ISDN is a core technology. A telephonenetwork can be thought of as a collection of wires strung between switching systems. The common electricalspecification for the signals on these wires is T1 or E1. Between telephone company switches, the signaling isperformed via SS7. Normally, a PBX is connected via a T1 with robbed bit signaling to indicate on-hook oroff-hook conditions and MF and DTMF tones to encode the destination number. ISDN is much better becausemessages can be sent much more quickly than by trying to encode numbers as long (100 ms per digit) tonesequences. This results in faster call setup times. Also, a greater number of features are available and fraud isreduced.

ISDN is also used as a smart-network technology intended to add new services to the public switchedtelephone network (PSTN) by giving users direct access to end-to-end circuit-switched digital services and as abackup or failsafe circuit solution for critical use data circuits.

ISDN and broadcast industry

ISDN is used heavily by the broadcast industry as a reliable way of switching low-latency, high-quality, long-distance audio circuits. In conjunction with an appropriate codec using MPEG or various manufacturersproprietary algorithms, an ISDN BRI can be used to send stereo bi-directional audio coded at 128 kbit/s with20 Hz 20 kHz audio bandwidth, although commonly the G.722 algorithm is used with a single 64 kbit/s Bchannel to send much lower latency mono audio at the expense of audio quality. Where very high quality audiois required multiple ISDN BRIs can be used in parallel to provide a higher bandwidth circuit switchedconnection. BBC Radio 3 commonly makes use of three ISDN BRIs to carry 320 kbit/s audio stream for liveoutside broadcasts. ISDN BRI services are used to link remote studios, sports grounds and outside broadcastsinto the main broadcast studio. ISDN via satellite is used by field reporters around the world. It is also commonto use ISDN for the return audio links to remote satellite broadcast vehicles.

In many countries, such as the UK and Australia, ISDN has displaced the older technology of equalisedanalogue landlines, with these circuits being phased out by telecommunications providers. IP-based streamingcodecs are starting to gain a foothold in the broadcast sector, using broadband internet to connect remotestudios. However, reliability and latency is crucially important for broadcasters and the quality of service offeredby ISDN has not yet been matched by packet switched alternatives.

Countries

United States and Canada



ISDN-BRI never gained popularity as a general use telephone access technology in Canada and the US, and

remains a niche product. The service was seen as a solution in search of a problem,[8] and the extensive arrayof options and features were difficult for customers to understand and use. ISDN has long been known byderogatory backronyms highlighting these issues, such as It Still Does Nothing, Innovations Subscribers

Don't Need, and I Still Don't kNow.[9][10]

Once the concept of broadband Internet access came to be associated with data rates incoming to the

customer at 256 kbit/s or more,[a] and alternatives like ADSL grew in popularity, the consumer market for BRIdid not develop. Its only remaining advantage is that while ADSL has a functional distance limitation and can useADSL loop extenders, BRI has a greater limit and can use repeaters. As such, BRI may be acceptable forcustomers who are too remote for ADSL. Widespread use of BRI is further stymied by some small North

American CLECs such as CenturyTel having given up on it and not providing Internet access using it.[14]

However, AT&T in most states (especially the former SBC/SWB territory) will still install an ISDN BRI lineanywhere a normal analog line can be placed and the monthly charge is roughly $55.

ISDN-BRI is currently primarily used in industries with specialized and very specific needs. High-endvideoconferencing hardware made by companies such as Sony, Polycom, Tandberg, and LifeSize via the

LifeSize Networker[15] can bond up to 8 B-channels together (using a BRI circuit for every 2 channels) toprovide digital, circuit-switched video connections to almost anywhere in the world. This is very expensive, andis being replaced by IP-based conferencing, but where cost concern is less of an issue than predictable qualityand where a QoS-enabled IP does not exist, BRI is the preferred choice.

Most modern non-VoIP PBXs use ISDN-PRI circuits. These are connected via T1 lines with the central officeswitch, replacing older analog two-way and direct inward dialing (DID) trunks. PRI is capable of deliveringCalling Line Identification (CLID) in both directions so that the telephone number of an extension, rather than acompany's main number, can be sent. It is still commonly used in recording studios, when a voice-over actor is

in one studio, but the director and producer are in a studio at another location.[4] The ISDN protocol deliverschannelized, not-over-the-Internet service, powerful call setup and routing features, faster setup and tear down,superior audio fidelity as compared to POTS (plain old telephone service), lower delay and, at higher densities,lower cost.

In 2013, Verizon announced it would no longer take orders for ISDN service in the Northeastern United

States.[4]

India

Bharat Sanchar Nigam Limited, Reliance Communications and Bharti Airtel are the largest communicationservice providers, and offer both ISDN BRI and PRI services across the country. Reliance Communicationsand Bharti Airtel uses the DLC technology for providing these services. With the introduction of broadbandtechnology, the load on bandwidth is being absorbed by ADSL. ISDN continues to be an important backup

network for point-to-point leased line customers such as banks, Eseva Centers,[16] Life Insurance Corporationof India, and SBI ATMs.

Japan

On April 19, 1988, Japanese telecommunications company NTT began offering nationwide ISDN servicestrademarked INS Net 64, and INS Net 1500, a fruition of NTT's independent research and trial from the

1970s of what it referred to the INS (Information Network System).[17]



German stamp

Previously, on April 1985, Japanese digital telephone exchange hardware made by Fujitsu was used toexperimentally deploy the world's first I interface ISDN. The I interface, unlike the older and incompatible Yinterface, is what modern ISDN services use today.

Since 2000, NTT's ISDN offering have been known as FLET's ISDN, incorporating the "FLET's" brand thatNTT uses for all of its ISP offerings.

In Japan, the number of ISDN subscribers dwindled as alternative technologies such as ADSL, cable Internetaccess, and fiber to the home gained greater popularity. On November 2, 2010, NTT announced plans tomigrate their backend from PSTN to the IP network from around 2020 to around 2025. For this migration,

ISDN services will be retired, and fiber optic services are recommended as an alternative.[18]

United Kingdom

In the United Kingdom, British Telecom (BT) provides ISDN2e (BRI) as well as ISDN30 (PRI). Until April2006, they also offered services named Home Highway and Business Highway, which were BRI ISDN-basedservices that offered integrated analogue connectivity as well as ISDN. Later versions of the Highway productsalso included built-in Universal serial bus (USB) sockets for direct computer access. Home Highway wasbought by many home users, usually for Internet connection, although not as fast as ADSL, because it wasavailable before ADSL and in places where ADSL does not reach.

France

France Telecom offers ISDN services under their product name Numeris (2 B+D), of which a professional Duoand home Itoo version is available. ISDN is generally known as RNIS in France and has widespreadavailability. The introduction of ADSL is reducing ISDN use for data transfer and Internet access, although it isstill common in more rural and outlying areas, and for applications such as business voice and point-of-saleterminals.

Germany

In Germany, ISDN is very popular with an installed base of 25 millionchannels (29% of all subscriber lines in Germany as of 2003 and 20%of all ISDN channels worldwide). Due to the success of ISDN, thenumber of installed analog lines is decreasing. Deutsche Telekom(DTAG) offers both BRI and PRI. Competing phone companiesoften offer ISDN only and no analog lines. However, these operatorsgenerally offer free hardware that also allows the use of POTS

equipment, such as NTBAs[b] with integrated terminal adapters.Because of the widespread availability of ADSL services, ISDN istoday primarily used for voice and fax traffic, but is still very popularthanks to the pricing policy of German telecommunication providers.

Today ISDN (BRI) and ADSL/VDSL are often bundled on the same line, mainly because the combination ofADSL with an analog line has no cost advantage over a combined ISDN-ADSL line. Some German operatorsstarted to implement Next Generation Networking, generally realized via DSL and unbundled local loop.However, a few operators offer the same services via the cable television infrastructure or, in selected areas, viaFTTH. Because of the popularity of ISDN, virtually all these telecommunication providers bundle their productswith residential gateways that include both integrated analog telephony adapters and ISDN-NGN adapters.



Greece

OTE, the incumbent telecommunications operator, offers ISDN BRI (BRA) services in Greece. Following thelaunch of ADSL in 2003, the importance of ISDN for data transfer began to decrease and is today limited toniche business applications with point-to-point requirements.

International deployment

A study[20] of the German Department of Science shows the following spread of ISDN-channels per 1000inhabitants in the year 2005:

Norway 401

Denmark 339

Germany 333

Switzerland 331

Japan 240

UK 160

Finland 160

Sweden 135

Italy 105

France 85

Spain 58

United States 47

Configurations

In ISDN, there are two types of channels, B (for "bearer") and D (for "data"). B channels are used for data(which may include voice), and D channels are intended for signaling and control (but can also be used fordata).

There are two ISDN implementations. 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.Together these three channels can be designated as 2B+D. Primary Rate Interface (PRI), also called primaryrate access (PRA) in Europe contains a greater number of B channels and a D channel with a bandwidth of64 kbit/s. The number of B channels for PRI varies according to the nation: in North America and Japan it is23B+1D, with an aggregate bit rate of 1.544 Mbit/s (T1); in Europe, India and Australia it is 30B+1D, with anaggregate bit rate of 2.048 Mbit/s (E1). Broadband Integrated Services Digital Network (BISDN) isanother ISDN implementation and it is able to manage different types of services at the same time. It is primarilyused within network backbones and employs ATM.

Another alternative ISDN configuration can be used in which the B channels of an ISDN BRI line are bonded toprovide a total duplex bandwidth of 128 kbit/s. This precludes use of the line for voice calls while the internetconnection is in use. The B channels of several BRIs can be bonded, a typical use is a 384K videoconferencingchannel.



Using bipolar with eight-zero substitution encoding technique, call data is transmitted over the data (B) channels,with the signaling (D) channels used for call setup and management. Once a call is set up, there is a simple 64kbit/s synchronous bidirectional data channel (actually implemented as two simplex channels, one in eachdirection) between the end parties, lasting until the call is terminated. There can be as many calls as there arebearer channels, to the same or different end-points. Bearer channels may also be multiplexed into what may beconsidered single, higher-bandwidth channels via a process called B channel BONDING, or via use of Multi-Link PPP "bundling" or by using an H0, H11, or H12 channel on a PRI.

The D channel can also be used for sending and receiving X.25 data packets, and connection to X.25 packetnetwork, this is specified in X.31. In practice, X.31 was only commercially implemented in UK, France andJapan.

Reference points

A set of reference points are defined in the ISDN standard to refer to certain points between the telco and theend user ISDN equipment.

R defines the point between a non-ISDN terminal equipment 2 (TE2) device and a terminal adapter

(TA) which provides translation to and from such a device

S defines the point between the ISDN terminal equipment 1 (TE1) or TA and a Network Termination

Type 2 (NT2) device

T defines the point between the NT2 and network termination 1 (NT1) devices.

Most NT-1 devices can perform the functions of the NT2 as well, and so the S and T reference points aregenerally collapsed into the S/T reference point.

In North America, the NT1 device is considered customer premises equipment (CPE) and must be maintainedby the customer, thus, the U interface is provided to the customer. In other locations, the NT1 device ismaintained by the telco, and the S/T interface is provided to the customer. In India, service providers provide Uinterface and an NT1 may be supplied by Service provider as part of service offering.

Types of communications

Among the kinds of data that can be moved over the 64 kbit/s channels are pulse-code modulated voice calls,providing access to the traditional voice PSTN. This information can be passed between the network and theuser end-point at call set-up time. In North America, ISDN is now used mostly as an alternative to analogconnections, most commonly for Internet access. Some of the services envisioned as being delivered over ISDNare now delivered over the Internet instead. In Europe, and in Germany in particular, ISDN has beensuccessfully marketed as a phone with features, as opposed to a POTS phone with few or no features.Meanwhile, features that were first available with ISDN (such as Three-Way Calling, Call Forwarding, CallerID, etc.) are now commonly available for ordinary analog phones as well, eliminating this advantage of ISDN.Another advantage of ISDN was the possibility of multiple simultaneous calls (one call per B channel), e.g. forbig families, but with the increased popularity and reduced prices of mobile telephony this has become lessinteresting as well, making ISDN unappealing to the private customer. However, ISDN is typically more reliablethan POTS, and has a significantly faster call setup time compared with POTS, and IP connections over ISDNtypically have some 3035ms round trip time, as opposed to 120180ms (both measured with otherwiseunused lines) over 56k or V.34/V.92 modems, making ISDN more reliable and more efficient fortelecommuters.



Where an analog connection requires a modem, an ISDN connection requires a terminal adapter (TA). Thefunction of an ISDN terminal adapter is often delivered in the form of a PC card with an S/T interface, andsingle-chip solutions seem to exist, considering the plethora of combined ISDN- and ADSL-routers.

ISDN is commonly used in radio broadcasting. Since ISDN provides a high quality connection this assists indelivering good quality audio for transmission in radio. Most radio studios are equipped with ISDN lines as theirmain form of communication with other studios or standard phone lines. Equipment made by companies such asTelos/Omnia (the popular Zephyr codec), Comrex, Tieline and others are used regularly by radio broadcasters.Almost all live sports broadcasts on radio are backhauled to their main studios via ISDN connections.

Sample call

The following is an example of a Primary Rate (PRI) ISDN call showing the Q.921/LAPD and theQ.931/Network message intermixed (i.e. exactly what was exchanged on the D-channel). The call is originatingfrom the switch where the trace was taken and goes out to some other switch, possibly an end-office LEC, whoterminates the call.

The first line format is . If themessage is an ISDN level message, then a decoding of the message is attempted showing the variousInformation Elements that make up the message. All ISDN messages are tagged with an ID number relative tothe switch that started the call (local/remote). Following this optional decoding is a dump of the bytes of themessage in ... ... format.

The RR messages at the beginning prior to the call are the keep alive messages. SETUP message indicate thestart of the call. Each message is acknowledged by the other side with a RR.

10:49:47.33 21/1/24 R RR

0000 02 01 01 a5 ....

10:49:47.34 21/1/24 T RR

0000 02 01 01 b9 ....

10:50:17.57 21/1/24 R RR

0000 02 01 01 a5 ....

10:50:17.58 21/1/24 T RR

0000 02 01 01 b9 ....

10:50:24.37 21/1/24 T SETUP

Call Reference : 000062-local

Bearer Capability : CCITT, Speech, Circuit mode, 64 kbit/s

Channel ID : Implicit Interface ID implies current span, 21/1/5, Exclusive

Calling Party Number : 8018023000 National number User-provided, not screened Presentation allowed

Called Party Number : 3739120 Type: SUBSCRB

0000 00 01 a4 b8 08 02 00 3e 05 04 03 80 90 a2 18 03 .......>........

0010 a9 83 85 6c 0c 21 80 38 30 31 38 30 32 33 30 30 ...l.!.801802300

0020 30 70 08 c1 33 37 33 39 31 32 30 0p..3739120

10:50:24.37 21/1/24 R RR

0000 00 01 01 a6 ....

10:50:24.77 21/1/24 R CALL PROCEEDING


Channel ID : Implicit Interface ID implies current span, 21/1/5, Exclusive

0000 02 01 b8 a6 08 02 80 3e 02 18 03 a9 83 85 .......>......

10:50:24.77 21/1/24 T RR

0000 02 01 01 ba ....

10:50:25.02 21/1/24 R ALERTING




Progress Indicator : CCITT, Public network serving local user,

In-band information or an appropriate pattern is now available

0000 02 01 ba a6 08 02 80 3e 01 1e 02 82 88 .......>.....

10:50:25.02 21/1/24 T RR

0000 02 01 01 bc ....

10:50:28.43 21/1/24 R CONNECT


0000 02 01 bc a6 08 02 80 3e 07 .......>.

10:50:28.43 21/1/24 T RR

0000 02 01 01 be ....

10:50:28.43 21/1/24 T CONNECT_ACK


0000 00 01 a6 be 08 02 00 3e 0f .......>.

10:50:28.44 21/1/24 R RR

0000 00 01 01 a8 ....

10:50:35.69 21/1/24 T DISCONNECT


Cause : 16, Normal call clearing.

0000 00 01 a8 be 08 02 00 3e 45 08 02 8a 90 .......>E....

10:50:35.70 21/1/24 R RR

0000 00 01 01 aa ....

10:50:36.98 21/1/24 R RELEASE


0000 02 01 be aa 08 02 80 3e 4d .......>M

10:50:36.98 21/1/24 T RR

0000 02 01 01 c0 ....

10:50:36.99 21/1/24 T RELEASE COMPLETE


0000 00 01 aa c0 08 02 00 3e 5a .......>Z

10:50:36.00 21/1/24 R RR

0000 00 01 01 ac ....

10:51:06.10 21/1/24 R RR

0000 02 01 01 ad ....

10:51:06.10 21/1/24 T RR

0000 02 01 01 c1 ....

10:51:36.37 21/1/24 R RR

0000 02 01 01 ad ....

10:51:36.37 21/1/24 T RR

0000 02 01 01 c1 ....

See also

Protocols

ISDN User Part (ISUP)

DSS1 (ETSI "Euro-ISDN", also used in many non-European countries)

DSS2 (Digital Subscriber Signalling System No. 2)



ETS 300 specification at ETSI (http://portal.etsi.org/mbs/Referenced%20Documents/ets_300_387.pdf)

NI-1 (US National ISDN Phase 1)

NI-2 (US National ISDN Phase 2)

4ESS (Lucent 4ESS specific protocol defined in AT&T TR 41459)

INS-NET 64/1500 (Japanese national/NTT carrier-specific protocol)

DACS used in the UK by British Telecom it uses non standard D channel signalling for pair gain

QSIG

Remote Operations Service Element protocol (ROSE)

Q.931

FTZ 1 TR 6 (obsolete German national protocol)

TS.013/TS.014 (obsolete Australian national protocol)

VN2/VN3/VN4 (obsolete French national protocols)

Specifications defining the physical layer and part of the data link layers of ISDN:

ISDN BRI: ITU-T I.430.

ISDN PRI: ITU-T I.431.

From the point of view of the OSI architecture, an ISDN line has a stack of three protocols

physical layer

data link layer

network layer (the ISDN protocol, properly)

Other

CAPI

ADSL

ATM

B-ISDN

Internet

IpDTL

H.320

ETSI

List of device bandwidths

Notes

1. ^ Broadband Internet access: Although various minimum bandwidths have been used in definitions of



broadband, ranging up from 64 kbit/s up to 1.0 Mbit/s, the 2006 OECD report[11] is typical by defining

broadband as having download data transfer rates equal to or faster than 256 kbit/s, while the United States

FCC, as of 2008, defines broadband as anything above 768 kbit/s.[12][13] The trend is to raise the threshold of

the broadband definition as the marketplace rolls out faster services.[13]

2. ^ "Network Termination for ISDN Basic Access", little boxes that bridge the two-wire UK0 line to the four-

wire S0 bus.[19]

References

1. ^ Decina, M; Scace, E (May 1986). "CCITT Recommendations on the ISDN: A Review". CCITT Red Book 4

(3): 32025. doi:10.1109/JSAC.1986.1146333 (https://dx.doi.org/10.1109%2FJSAC.1986.1146333).

ISSN 0733-8716 (https://www.worldcat.org/issn/0733-8716).

2. ^ Aaron, R; Wyndrum, R (March 1986). "Future trends"

(http://ieeexplore.ieee.org/iel5/35/23852/01093028.pdf) (PDF). IEEE Communications Magazine (AT&T Bell

Laboratories) 24 (3): 3843. doi:10.1109/MCOM.1986.1093028

(https://dx.doi.org/10.1109%2FMCOM.1986.1093028). Retrieved 2 September 2007.

3. ^ Robin, G; Treves, S (July 1979). "Pragmatic Introduction of Digital Switching and Transmission in Existing

Networks". IEEE Transactions on Communications 27 (7): 1071. doi:10.1109/TCOM.1979.1094494

(https://dx.doi.org/10.1109%2FTCOM.1979.1094494).

4. ^a b c "Verizon: No Longer Taking Orders for ISDN Service in Northeast Starting May 18"

(http://www.talkers.com/2013/03/28/verizon-no-longer-taking-orders-for-isdn-service-in-northeast-starting-

may-18/). Talkers. March 28, 2013. Retrieved April 6, 2013.

5. ^ "What is ISDN?" (http://public.swbell.net/ISDN/overview.html). Southwestern Bell. Retrieved April 6, 2013.

6. ^ "What Is Basic Rate Interface?" (http://www.wisegeek.com/what-is-basic-rate-interface.htm). Retrieved

April 6, 2013.

7. ^ "ISDN\SwitchType" (http://msdn.microsoft.com/en-

us/library/windows/hardware/ff541725%28v=vs.85%29.aspx). Microsoft. Retrieved April 6, 2013.

8. ^ "ISDN: A Solution in Search of a Problem"

(http://www.japaninc.com/cpj/magazine/issues/1995/sep95/09isdn.html), Computing Japan Magazine (article),

SeptemberOctober 1995.

9. ^ Green, James Harry (26 October 2005). The Irwin Handbook of Telecommunications

(http://books.google.com/books?id=L1iJaXDV89gC&pg=PA262) (5 ed.). McGraw-Hill Professional. p. 770.

ISBN 978-0-07-145222-9. Retrieved 12 May 2012.

10. ^ Bodin, Madeline; Dawson, Keith (3 January 2002). The Call Center Dictionary: The Complete Guide to Call

Center & Customer Support Technology Solutions (http://books.google.com/books?

id=CTXhqkFDQKQC&pg=PA101). Focal Press. p. 227. ISBN 978-1-57820-095-5. Retrieved 12 May 2012.

11. ^ Broadband Statistics

(http://www.oecd.org/document/7/0,3343,en_2649_34223_38446855_1_1_1_1,00.html) (report), OECD,

2006.

12. ^ Martin, Kevin J, Statement of Chairman (http://hraunfoss.fcc.gov/edocs_public/attachmatch/DOC-

280909A2.doc) (MS Word doc), US: FCC.

13. ^a b "FCC redefines "broadband" to mean 768 kbit/s, "fast" to mean "kinda slow""

(http://www.engadget.com/2008/03/19/fcc-redefines-broadband-to-mean-768kbps-fast-to-mean-kinda/),

Engadget, 2008-03-19.



Wikibooks has a book onthe topic of: Nets, Websand the InformationInfrastructure

External links

Published recommendations available in English, French

and Spanish (http://www.itu.int/rec/T-REC-I/e) (list), ITU.

Fine, ISDN (http://hea-www.harvard.edu/~fine/ISDN/),

Harvard.

B, Ralph, ISDN (http://www.ralphb.net/ISDN/).

ISDN (http://www.roblee.com/isdn.htm), Roblee.

Retrieved from "http://en.wikipedia.org/w/index.php?title=Integrated_Services_Digital_Network&oldid=649132688"

Categories: ITU-T recommendations Network access Telephony Integrated Services Digital Network

Videotelephony Audio network protocols

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apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia is a registeredtrademark of the Wikimedia Foundation, Inc., a non-profit organization.

Engadget, 2008-03-19.

14. ^ "Disclaimer", Internet Access service offerings

(http://www.centurytel.com/Pages/Disclaimers/internetDisclaimer.jsp), CenturyTel, "You may not obtain

Internet services over ISDN lines (BRI or PRI), dedicated circuits or special service circuits".

15. ^ "Networker", Infrastructure products (http://www.lifesize.com/en/Products/Infrastructure/Networker.aspx),

LifeSize.

16. ^ Online (http://www.esevaonline.com/), Eseva.

17. ^ "NTT - " (http://denwakyoku.jp/kitahama.html) (in Japanese). JP: Denwakyoku. |chapter=

ignored (help)

18. ^ "PTSN" (http://www.ntt-

east.co.jp/release/1011/pdf/101102a_1.pdf) (in Japanese). JP: NTT East. November 2, 2010.

19. ^ "Network Termination for ISDN Basic rate Access", Wikipedia (in German), Wikimedia.

20. ^ "ISDN-Verbreitung", Studie (http://web.archive.org/web/20081002180402/http://www.bmbf.de/pub/sdi-19-

07.pdf) (PDF), DE: BMBF, archived from the original (http://www.bmbf.de/pub/sdi-19-07.pdf) on 2008-10-

02.