1、 AMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS ATIS-1000620.1991(R2012) Integrated Services Digital Network (ISDN) Circuit-Mode Bearer Service Category Description ATIS is the leading technical planning and standards development organization committed to the rapid development of global, market-d
2、riven standards for the information, entertainment and communications industry. More than 200 companies actively formulate standards in ATIS Committees and Forums, covering issues including: IPTV, Cloud Services, Energy Efficiency, IP-Based and Wireless Technologies, Quality of Service, Billing and
3、Operational Support, Emergency Services, Architectural Platforms and Emerging Networks. In addition, numerous Incubators, Focus and Exploratory Groups address evolving industry priorities including Smart Grid, Machine-to-Machine, Connected Vehicle, IP Downloadable Security, Policy Management and Net
4、work Optimization. ATIS is the North American Organizational Partner for the 3rd Generation Partnership Project (3GPP), a member and major U.S. contributor to the International Telecommunication Union (ITU) Radio and Telecommunications Sectors, and a member of the Inter-American Telecommunication Co
5、mmission (CITEL). ATIS is accredited by the American National Standards Institute (ANSI). For more information, please visit .AMERICAN NATIONAL STANDARD Approval of an American National Standard requires review by ANSI that the requirements for due process, consensus, and other criteria for approval
6、 have been met by the standards developer. Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement has been reached by directly and materially affected interests. Substantial agreement means much more than a simple majority, but not necessarily una
7、nimity. Consensus requires that all views and objections be considered, and that a concerted effort be made towards their resolution. The use of American National Standards is completely voluntary; their existence does not in any respect preclude anyone, whether he has approved the standards or not,
8、 from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the standards. The American National Standards Institute does not develop standards and will in no circumstances give an interpretation of any American National Standard. Moreover, no person sha
9、ll have the right or authority to issue an interpretation of an American National Standard in the name of the American National Standards Institute. Requests for interpretations should be addressed to the secretariat or sponsor whose name appears on the title page of this standard. CAUTION NOTICE: T
10、his American National Standard may be revised or withdrawn at any time. The procedures of the American National Standards Institute require that action be taken periodically to reaffirm, revise, or withdraw this standard. Purchasers of American National Standards may receive current information on a
11、ll standards by calling or writing the American National Standards Institute. Notice of Disclaimer 1200 G Street, NW, Washington, DC 20005.This standard was processed and approved for submittal to ANSI byAccredited Standards Committee on Telecommunications, T1. Committeeapproval of the standard does
12、 not imply that all committee members votedfor its approval. At the time it approved this standard, Committee T1 hadthe following members:Ivor N. Knight, ChairmanArthur K. Reilly, Vice-ChairmanO.J. Gusella, Jr., SecretaryOrganization Represented Names of RepresentativesEXCHANGE CARRIERSAmeritech Ser
13、vices, Inc. Laurence A. YoungRobert Koren (Alt.)Bell Atlantic Corporation John W. SeazholtzRoger Nucho (Alt.)Bellcore.Gary. G. SchlangerRalph E. Jensen (Alt.)Bellsouth Services.Leonard Strickland, Jr.William J. McNamara, IIICentel Corporation Bruce BeckerCincinnati Bell Telephone William P. KeidelT.
14、C. Grimes (Alt.)Contel Corporation Steve LinskeyStephen P. Welsh (Alt.)Exchange Carriers Standards AssociationJoseph MendozaGregory L. Theus (Alt.)GTE SC/Telephone OperationsGregory L. TheusRichard L. Cochran (Alt.)National Telephone Cooperative Association .Joseph M. FlaniganNYNEX Service CompanyJa
15、mes F. BaskinLeo Katz (Alt.)Pacific Bell Fred DoellStanley Chum (Alt.)Puerto Rico Telephone Company.Segundo RuizSouthwestern Bell Corporation C.C. BaileyJoseph Mendoza (Alt.)(Alt.)iiiivOrganization Represented Name of RepresentativeUnited States Telephone Association (USTA) Paul K. HartThomas Gajesk
16、i (Alt.)United Telecommunications, Inc. .Robert P. McCabeHarold L. Fuller (Alt.)U S West.James L. EitelJames Dahl (Alt.)INTEREXCHANGE CARRIERSAmerican Mobile Satellite Corporation .Michael K. WardWilliam Garner (Alt.)ATb) Circuit-Mode, 64-kbit/s, 8-kHz Struc-tured Bearer Service Category usable for3
17、.1-KHz audio information transfer. This ser-vice may also be referred to as Circuit-ModeVoice-Band Data;c) Circuit-Mode, 64-kbit/s, Unrestricted, 8- kHz Structured Bearer Service. This ser-CCITT Recommendation I.220, Commondynamic description of basic telecommunica-tion services 2)CCITT Recommendati
18、on I.230, Definition ofbearer service categories 2)CCITT Recommendation I.231, Circuit-modebearer service categories 2)CCITT Recommendation I.520, Generalarrangements for network interworkingbetween ISDNs 2)CCITT Recommendation I.530, Network inter-working between an ISDN and a PublicSwitched Teleph
19、one Network (PSTN) 2)3 Definitions 3.1 multi-point configuration: A configura-tion where there are more than two accesspoints.3.2 network: In this description, networkrefers to all telecommunications equipment thathas any part in processing a call or a supple-mentary service for the user referred to
20、. It mayinclude the Local Exchange, TransitExchanges, and NT2s, but does not include theISDN terminal and is not limited to the “Public”network or any particular set of equipment. 3.4 NDUB (Network-Determined UserBusy): This is a condition of an interface, asdetermined by the network, based on the n
21、et-works capability to terminate another call tothat interface. The interface is said to be NDUBif any of the following conditions exist: If the maximum number of informationchannels available has been reached andthe network does not support the offering ofadditional calls beyond this number; If the
22、 limit of additional offering had beenreached; If the maximum number of total calls sup-ported for User B has been reached. 3.4 no answer timer: This optional timerspecifies the period of time the network will waitfor a response (answer) from any one of the ter-minals on the interface of the called
23、subscriber. 3.5 point-to-point configuration: A configu-ration where there are only two access points. ANSI T1.620-19912ANSI T1.620-1991vice may also be referred to as Circuit-ModeDigital;d) Circuit-Mode, 64-kbit/s, 8-kHz Struc-tured Bearer Service Category, usable formulti-use bearer capability inf
24、ormationtransfer. This service may also be referred toas Circuit-Mode Multi-Use Bearer Capability;e) Circuit-Mode, 384-kbit/s, Unrestricted, 8-kHz Structured Bearer Service;f) Circuit-Mode, 1472-kbit/s Unrestricted,8-kHz Structured Bearer Service;g) Circuit-Mode, 1536-kbit/s Unrestricted,8-kHz Struc
25、tured Bearer Service.4.1 Circuit-mode, 64-kbit/s, 8-kHz struc-tured bearer service category usable forspeech information transfer This bearer service category is intended tosupport speech. The digital signal at the usernetwork inter-face reference point shall conform to CCITTRecommendation G.711 -la
26、w. The networkmay use processing techniques appropriatefor speech such as analog transmission, echocancellation, and low bit-rate voice encoding.Hence, bit integrity is not ensured. This bearerservice is not intended to support modem-derived voice-band data. This Circuit-Mode bearer service category
27、 allows: two users (e.g., terminals, PBXs) in apoint-to-point configuration to communicatevia the ISDN using speech encoding into 64-kbit/s digital signals over the B-channel,in both directions continuously and simulta-neously for the duration of a call; three or more users in a multipoint config-ur
28、ation as provided by supplementary ser-vices, such as conference calling. This bearer service category is transferred overa B-channel; signaling is provided in the D-channel in the same interface structure or in theD-channel of another interface structure withinthe same ISDN customer access arrangem
29、ent.Tones and announcements to indicate theprogress or status of a call, may be providedby the network. The attribute values for this bearer servicecategory are as contained in ANSI T1.604 andT1.603 except that the communication config-uration may also be “multipoint” through theuse of a conferencin
30、g arrangement. 4.2 Circuit-Mode, 64-kbit/s, 8-kHz struc-tured bearer service category usable for 3.1- kHz audio information transferThis bearer service category corresponds tothe service that is currently offered in thePSTN. This bearer service category providesfor the transfer of speech and for the
31、 transferof 3.1-kHz bandwidth audio information suchas speech and voice band data via modems,facsimile group 1, 2, and 3 information (seenote). The digital signal at the usernetworkinterface reference point shall conform toCCITT Recommendation G.711 -law.NOTE The maximum modem bit-rate that canbe us
32、ed by users in applications of this bearerservice depends on the modulation standardemployed by the user and on the transmissionperformance within or between different net-works. The extent of support is a network or bilat-erally agreed matter. Connections provided for these servicesshould offer the
33、 transfer capability for theinformation indicated indicated in the previousparagraph. (This means that the network mayinclude speech processing techniques, provid-ed they are appropriately modified or function-ally removed prior to non-speech informationtransfer). For example, 2100 Hz (disabling)inb
34、and tones, possibly including phase rever-sals, are used to control speech processingdevices such as echo control devices. Bitintegrity of the 64-kbit/s bearer service is notensured. This Circuit-Mode bearer service categoryallows: two users (e.g., terminals, PBXs) in apoint-to-point configuration t
35、o communicatevia the ISDN using CCITT RecommendationG.711 -law encoding into 64-kbit/s digitalsignals over the B-channel, in both direc-tions continuously and simultaneously forthe duration of a call; three or more users in a multipoint config-uration as provided by supplementary ser-vices such as c
36、onference calling.This bearer service category is transferredover a B-channel; signaling is provided in the3recognize that no network provision can be madefor the control of such items as echo and loss, asthe network is unaware of the application in use.Furthermore, the quality of service attribute
37、valuefor information transfer delay will indicate the suit-ability of a particular version of this bearer servicefor speech.This Circuit-Mode bearer service categoryallows two users (e.g., terminals, PABXs) in apoint-to-point configuration to communicatevia the ISDN using 64-kbit/s digital signalsov
38、er the B-channel, in both directions continu-ously and simultaneously for the duration of acall.The attribute values for this bearer servicecategory are as contained in ANSI T1.604 andT1.603.4.4 Circuit-mode, 64-kbit/s, 8-kHz structuredbearer service category, usable for multi-usebearer capability i
39、nformation transferThis bearer service category provides thetransfer of unrestricted digital informationbetween 7-kHz audio terminals on the ISDN(e.g., 7-kHz bandwidth audio informationencoded in accordance with CCITT Recom-mendations G.722/G.725). As noted in Item(d) of clause 7, it also provides f
40、or the transferof speech or 3.1-kHz audio information encod-ed in accordance with CCITT Recommenda-tion G.711 -law between a calling 7-kHzaudio terminal and either a terminal on thePSTN or a speech or 3.1-kHz audio terminalon the ISDN. Connections between 7-kHzaudio terminals provided for this circu
41、it shallnot modify the transmission of the informationindicated above. That is, the network shall notinclude speech processing techniques unlessa request for processing is received, such asin a multipoint configuration.This Circuit-Mode bearer service categoryallows two users (e.g., terminals, PABXs
42、) in apoint-to-point configuration to communicateD-channel in the same interface structure or inthe D-channel of another interface structurewithin the same ISDN customer accessarrangement. Tones and announcements to indicate theprogress or status of a call, may be providedby the network. The attribu
43、te values for this bearer servicecategory are as contained in ANSI T1.604 andT1.603 except that the communication config-uration may also be “multipoint” through theuse of a conferencing arrangement. 4.3 Circuit-Mode, 64-kbit/s, unrestricted, 8-kHz structured bearer service category A Circuit-Mode,
44、64-kbit/s, unrestricted, bearerservice3)provides information transfer withoutalteration between usernetwork interface ref-erence points. It may, therefore, be used tosupport various user applications. Examplesinclude speech (see note); 3.1 kHz audio (see note); multiple subrate information streams m
45、ul-tiplexed into 64 kbit/s by the user. transparent access to a packet-switchedpublic or private network using X.25 (I.462case a); transparent access to a packet-switchedpublic or private network using frame relay.This bearer service category is transferredover a B-channel; signaling is provided in
46、theD-channel in the same interface structure or inthe D-channel of another interface structurewithin the same ISDN customer accessarrangement.NOTE Although speech and 3.1-kHz audio havebeen given as applications for this bearer service,it is recognized that it is the responsibility of thecustomers t
47、o ensure that a compatible encodingscheme is in operation. Customers should alsoANSI T1.620-199143) During an interim period, some networks may only support restricted 64-kbit/s digital information transfercapability, i.e., information transfer capability solely restricted by the requirement that th
48、e all-ZERO octet isnot allowed. For interworking, the rules given in appendix 1 of CCITT Recommendation I.520 should apply.The interworking functions have to be provided in the network with restricted 64-kbit/s capability. The ISDNwith 64-kbit/s transfer capabilities will not be affected by this int
49、erworking, other than by conveying the appro-priate signalling message to and from the ISDN terminal. Prior to the introduction of ISDN, some networksonly supported 56-kbit/s data transfer. As a result, some of these networks may continue to only use 56 kbit/scapabi.ity and potential ISDN users have 56-kbit/s terminals. As these networks begin to offer ISDN, theymay continue to support 56-kbit/s as a user adaption rate of the 64-kbit/s unrestricted bearer service.ANSI T1.620-1991via the ISDN using, for example, proceduresin CCITT Recommendation G.725 over theB
