SIST ETS 300 171 E1:2005

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Zasebno telekomunikacijsko omrežje (PTN) – Specifikacija, funkcijski modeli in informacijski pretoki - Vidiki krmiljenja za vodovne osnovne storitvePrivate Telecommunication Network (PTN); Specification, functional models and information flows; Control aspects of circuit mode basic services33.040.35Telefonska omrežjaTelephone networksICS:Ta slovenski standard je istoveten z:ETS 300 171 Edition 1SIST ETS 300 171 E1:2005en01-maj-2005SIST ETS 300 171 E1:2005SLOVENSKI
STANDARD
EUROPEANETS 300 171TELECOMMUNICATIONDecember 1992STANDARDSource: ETSI TC-ECMAReference: ECMA-142ICS:33.080Key words:PTN, BCSD, ECMA-142Private Telecommunication Network (PTN);Specification, functional models and information flowsControl aspects of circuit mode basic servicesETSIEuropean Telecommunications Standards InstituteETSI SecretariatPostal address: F-06921 Sophia Antipolis CEDEX - FRANCEOffice address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCEX.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: secretariat@etsi.frTel.: +33 92 94 42 00 - Fax: +33 93 65 47 16Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and theforegoing restriction extend to reproduction in all media.© European Telecommunications Standards Institute 1992. All rights reserved.SIST ETS 300 171 E1:2005New presentation - see History box

Page 2ETS 300 171: December 1992Whilst every care has been taken in the preparation and publication of this document, errors in content,typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to"ETSI Editing and Committee Support Dept." at the address shown on the title page.SIST ETS 300 171 E1:2005

Page 3ETS 300 171: December 1992ContentsForeword.71Scope.92References.103Definitions and acronyms.103.1Definitions.103.1.1Service.103.1.2Call.103.1.3Network call control entity.103.1.4User.103.1.5PTN user.103.2Acronyms.104PTN Service Provision.114.1Bearer Services.114.2Teleservices.114.3Control and signalling.124.4Interworking Considerations.124.5Service Model.124.6Service Attributes.135.Circuit mode 64 kbit/s unrestricted 8 kHz structured bearer service category.145.1Description.145.2Interworking Considerations.155.2.1Interworking with a public ISDN.155.2.2Interworking with networks supporting only a restricted digital informationtransfer capability.155.2.3Interworking with analogue networks.155.3Service attributes.165.3.1Dominant information transfer attributes.165.3.2Secondary information transfer attributes.165.3.3Access attributes.166Circuit mode 64 kbit/s 8 kHz structured bearer service category Usable for speech informationtransfer.166.1Description.166.2Interworking Considerations.176.2.1Interworking with a public ISDN.176.2.2Interworking with analogue networks.176.2.3Encoding law conversion.176.3Service attributes.176.3.1Dominant information transfer attributes.176.3.2Secondary information transfer attributes.186.3.3Access attributes.187Circuit mode 64 kbit/s 8 kHz structured bearer service category usable for 3,1 kHz audioinformation transfer.187.1Description.187.2Interworking Considerations.197.2.1Interworking with a public ISDN.197.2.2Interworking with analogue networks.197.2.3Encoding law conversion.197.3Service attributes.197.3.1Dominant information transfer attributes.197.3.2Secondary information transfer attributes.19SIST ETS 300 171 E1:2005

Page 4ETS 300 171: December 19927.3.3Access attributes.208Teleservices.208.1Telephony Teleservice.208.2Teletex Teleservice.218.3Telefax 4 Teleservice.218.4Videotex Teleservice.229Demand service procedures for services within a PTN.229.1Provision of Services.229.2Normal Procedures.229.2.1Call establishment at the calling PTN user.229.2.2Call establishment at the called PTN user.249.2.3Terminating the service (call release).259.3Exceptional Procedures / Unsuccessful Outcome.259.3.1Failure situations due to calling PTN user error.259.3.2Failure situations due to called PTN user state.259.3.3Failure situations due to network conditions.259.3.4Rejection of the call by the called PTN user.259.3.5Absence of response from called PTN user.2610Interworking.2610.1General Interworking Considerations.2610.1.1Incoming Calls.2610.1.2Outgoing Calls.2610.1.3PTN Transit Calls.2610.2Demand service interworking with a public ISDN.2710.2.1Receipt of service request from a public ISDN.2710.2.2Sending a service request to a public ISDN.2710.2.3Receipt of a service response from public ISDN.2710.2.4Sending a service response to a public ISDN.2811Dynamic Description.2812Functional model.3012.1Functional model description.3012.2Description of the functional entities.3112.2.1Call Control Agent functional entity.3112.2.1.1Originating CCA functional entity.3212.2.1.2Destination CCA functional entity.3212.2.2Call Control functional entity.3212.2.2.1Originating CC functional entity.3312.2.2.2Destination CC functional entity.3312.2.2.3Transit CC functional entity.3312.2.2.4Incoming and Outgoing Gateway CC functional entities.3413Definition of information flows.3413.1Conventions used within the description of information flows.3413.1.1Convention for the description of mandatory or optional information.3413.1.2Convention for the naming of information flows.3513.2SETUP.3513.3REPORT.3913.4CHANNEL_ACKNOWLEDGE.4013.5CHANNEL_CONNECT.4013.6DISCONNECT.4013.7RELEASE.4013.8INFORMATION.4013.9SETUP_REJECT.4114Information flow sequences.4114.1Functional Entity Actions.4114.1.1Originating CCA functional entity.4114.1.2Originating CC functional entity.42SIST ETS 300 171 E1:2005

Page 5ETS 300 171: December 199214.1.3Transit CC functional entity.4314.1.4Destination CC functional entity.4414.1.5Destination CCA functional entity.4514.1.6Incoming gateway CC functional entity.4514.1.7Outgoing gateway CC functional entity.4714.2Non-automatic Call Establishment.4814.3Automatic Answering.4914.4Unsuccessful calls with the provision of tones and announcements.5014.5Unsuccessful calls without the provision of tones and announcements.5114.6Incoming interworking with a non-ISDN.5214.7Outgoing interworking with a non-ISDN.5314.8Outgoing interworking with overlap sending.5414.9Basic call clearing.5514.10Incoming interworking with a public ISDN.5614.11Outgoing interworking with a public ISDN.5715SDL diagrams for functional entities.5815.1Originating CCA functional entity SDL diagrams.5815.1.1Originating CCA states used in SDL diagrams.5815.1.2Originating CCA SDL diagrams.5915.2Originating CC functional entity SDL diagrams.6315.2.1Originating CC states used in SDL diagrams.6315.3Transit CC functional entity SDL diagrams.7015.3.1Transit CC states used in SDL diagrams.7015.4Destination CC functional entity SDL diagrams.7615.4.1Destination CC states used in SDL diagrams.7615.5Destination CCA functional entity SDL diagrams.8315.5.1Destination CCA states used in SDL diagrams.8315.5.2Destination CCA SDL diagrams.8416Allocation of functional entities to physical entities.87Annex A (informative):Relationship to corresponding public ISDN Standards.88Annex B (informative):Other references.89History.90SIST ETS 300 171 E1:2005

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Page 7ETS 300 171: December 1992ForewordThis European Telecommunication Standard (ETS) has been produced by the European ComputerManufacturers Association (ECMA) on behalf of its members and those of the EuropeanTelecommunications Standards Institute (ETSI).This ETS is one of a series of Standards defining services and signalling protocols applicable to PrivateTelecommunication Networks (PTNs) incorporating one or more interconnected exchanges. The seriesuses the ISDN concepts as developed by CCITT and is also within the framework of standards for opensystems interconnection as defined by ISO.This particular ETS contains specifications of basic services.Service specifications are produced in three stages, according to the method described in ENV 41005,which is based on the method used by CCITT Recommendation I.130 and Recommendation Q.65 andETSI. This Standard contains the Stage 1 and Stage 2 specifications of the services. Stage 1 (clauses 5to 11) describes the services as seen by users of PTNs. Clauses 9,10 and 11 describe the commonaspects of the services and clauses 5,6,7 and 8 describe those aspects which are service dependent.Stage 2 (clauses 12 to 16) identifies the functional entities involved in the basic services and theinformation flows between them. Stage 3, the definition of the networking and access signalling protocolsto support the basic services, will appear in separate ETSs.This ETS was produced by ECMA using the ECMA guidelines for the production of ETSs and using theECMA stylesheet. In order to avoid undue delays in the publication of this ETS it has been agreed that thisETS will not be converted to the ETSI stylesheet.SIST ETS 300 171 E1:2005

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Page 9ETS 300 171: December 19921ScopeThis Standard specifies control aspects of standardized circuit mode services which may be supported byPrivate Telecommunication Networks (PTNs). This Standard contains the Stage 1 and Stage 2specifications of these services.Definition of signalling protocols at Stage 3 is guided and constrained by the Stage 1 and Stage 2specifications , and therefore this Standard is concerned mainly with the control aspects of services. Theproperties of the user information are described for the different basic services which have to becontrolled. Detailed requirements of user information protocols and switching functions are outside thescope of this Standard.NOTE 1:The services specified are compatible with the equivalent services specified by CCITT and ETSI for publicISDNs. CCITT specifications of these services are to be found in Recommendations I.220, I.230, I.231(Stage 1), Q.71 (Stage 2), I.240, and I.241.This Standard applies to the following bearer services:-Circuit Mode 64 kbit/s Unrestricted 8 kHz Structured Bearer Service Category;-Circuit Mode 64 kbit/s 8 kHz Structured Bearer Service Category Usable for Speech InformationTransfer;-Circuit Mode 64 kbit/s 8 kHz Structured Bearer Service Category Usable for 3,1 kHz AudioInformation Transfer.The following Teleservices are supported by these bearer services:-Telephony Teleservice;-Teletex Teleservice;-Telefax 4 Teleservice;-Videotex Teleservice.This Standard specifies the dynamic procedures for the support of these Teleservices within a PTN. Thedefinition of these Teleservices is beyond the scope of this Standard.Negotiation of service at call establishment time and change of service during a call are outside the scopeof this Standard.A Stage 3 Standard shall be in conformance with the Stage 1 and Stage 2 specifications contained in thisStandard, if the signalling protocols and equipment behaviour specified in the Stage 3 Standard arecapable of being used in a PTN which supports any or all of the basic services specified in this Standard.In particular, the Stage 3 Standards shall be adequate for the support of:-common aspects of the control of basic services, as seen by the PTN user and the interworkingwith the ISDN, as specified in clauses 9 and 10;-the control of the individual basic services specified in clauses 5, 6, 7 and 8;-the functional entities, functional entity allocations and information flows identified in clauses 12, 13,14 and 16.SIST ETS 300 171 E1:2005

Page 10ETS 300 171: December 19922ReferencesETS 300 189 (1992)Private Telecommunication Network (PTN); Addressing.ENV 41005 (1992)Method for the specification of basic and supplementary services of privatetelecommunication networks.ENV 41007-1 (1991)Definition of terms in private telecommunication networks, Part 1: definition ofgeneral terms.ETS 300 089 (1991)Integrated Services Digital Network (ISDN); Calling Line IdentificationPresentation (CLIP) supplementary service, Service description.ETS 300 062 (1991)Integrated Services Digital Network (ISDN); Direct Dialling In (DDI)supplementary service, Service description.ETS 300 094 (1991)Integrated Services Digital Network (ISDN); Connected Line IdentificationPresentation (COLP) supplementary service, Service description.CCITT Recommendation I.112Vocabulary of terms for ISDNs.3Definitions and acronymsThe special terminology defined in ENV 41007-1 and CCITT Recommendation I.112 applies. If there isconflict, the definitions in ENV 41007-1 shall take precedence. For the purpose of this Standard thefollowing further definitions apply.3.1Definitions3.1.1ServiceUnless otherwise stated, the term "service" shall mean "basic telecommunication service".3.1.2CallThe instance of the use of a service.3.1.3Network call control entityThe collection of network functions concerned with the control of services, as opposed to functionsconcerned with the transfer of user information.3.1.4UserAn entity which uses telecommunication services offered by a network, and which therefore directly orindirectly uses the services of the Network Layer.3.1.5PTN userAn entity which uses telecommunication services offered by a PTN, and which therefore directly orindirectly uses the services of the Network Layer.3.2AcronymsCC Clearing CauseCC Call Control generic functional entityCCA Call Control Agent generic functional entityCH Call HistoryCI Channel IdentifierCNConnected NumberSIST ETS 300 171 E1:2005

Page 11ETS 300 171: December 1992CS Connected SubaddressCT Connection TypeDC Destination CategoryDN Destination NumberDS Destination SubaddressDT Date/TimeFE functional entityISDN Integrated Services Digital NetworkISO International Organisation for StandardizationNC Number complete indicationOC Originating CategoryON Originating NumberOS Originating SubaddressOSI Open Systems InterconnectionPSTN Public Switched Telephone NetworkPTN Private Telecommunication NetworkPTNX Private Telecommunication Network ExchangeRT Report TypeSDL Specification and Description LanguageTE Terminal Equipment4PTN Service ProvisionBasic services within a PTN consist of bearer services and teleservices. A bearer service is defined onlyup to a certain layer, in any case no higher than Layer 3. The definition of a teleservice also encompassesthe higher layers up to Layer 7 (although some of the layers may be empty or not specified, as withTelephony, for example).The basic services defined in this document correspond to the circuit mode basic services defined byETSI.4.1Bearer ServicesPTN circuit mode bearer services provide a means of transferring information between users at PhysicalLayer level. Layers above Layer 3 are not defined. The provision of bearer services involves only low layerfunctions and so a bearer service can support a variety of high layer protocols.A circuit mode bearer service provides a connection (at the Physical Layer) for the conveyance of userinformation. Each switching point intervenes only at the Physical Layer. This gives a constant bit rate andfixed delays, which are very close to the inherent delays of the transmission media.4.2TeleservicesThe provision of a teleservice involves high layer functions, generally using the underlying low layercapabilities of bearer services. A PTN can support a teleservice by supporting a bearer service having thesame capabilities as those required by the teleservice and by satisfying any special control requirementsof the teleservice. The provision of high layer functions in support of a teleservice is not a necessary partof a PTN and is beyond the scope of this Standard.When requesting a teleservice from a PTN, the user has to explicitly indicate the bearer capabilitiesrequired in the same way as when a bearer service is requested. In addition, an indication of theteleservice required is provided by the PTN user, primarily for passing the indication through the networkto the called PTN user in order to allow compatibility checking. A PTN may optionally make use of thisinformation for purposes such as barring certain teleservices to certain PTN users, or for the provision oractivation of supplementary services on a per teleservice basis, e.g., call forwarding. Any use of thisinformation by a PTN is outside the scope of, but is not precluded by, this Standard.SIST ETS 300 171 E1:2005

Page 12ETS 300 171: December 19924.3Control and signallingIn order for information transfer to take place, an information connection must exist between the PTNusers concerned. A demand service involves the establishment and release of information connectionsaccording to the demands of users. From the point of view of users, calls have to be established andreleased, and this involves call control functions. Call control requires knowledge of the properties of theuser information to be transferred in order to provide appropriate capabilities.In general, more than one network element (e.g., PTNX, terminal) is involved in a call, and therefore callcontrol is distributed. Therefore call control information needs to be conveyed between network elements.The conveyance of this information is a function of signalling (see ECMA TR/44).PTN services use signalling, information which is carried over a dedicated logical connection, separatefrom the connection established for conveying user information. In the case of circuit mode bearerservices, the signalling connection is by necessity carried on a separate physical channel from theinformation channel (out-of-band signalling).NOTE 2:The possible use of the signalling connection also to provide user-to-user information transfer is thefunction of the User-to-User Signalling supplementary service, which is outside the scope of this Standard.4.4Interworking ConsiderationsIn general, interworking between a PTN bearer service and a bearer service provided by another networkrequires interworking functions, both for information transfer and for signalling.When interworking with the same service in a public ISDN, the interworking function for informationtransfer is null. However, interworking has an impact on signalling.4.5Service ModelThis Standard uses the following model in order to specify services.The Network Layer provides the bearer capabilities necessary for the support of bearer services andteleservices. A PTN user accesses the Network Layer service through Network Service Access Points(NSAP) and requests the Network Layer to provide the bearer capabilities necessary for the support of thebearer services or teleservices. An NSAP is identifiable by an address, which in a PTN is generally in theform of a PTN number, or of the concatenation of a PTN number and a subaddress. For addressingrequirements see ETS 300 189.The Network Layer incorporates functions for the control of calls and functions for the transfer of userinformation. This Standard views control functions as services being provided by a Network Call Controlentity, which are accessible through service access points. Co-ordination functions use the services of theNetwork Call Control entity when coordinating call control with the transfer of user information, therebyproviding a complete Network Layer service to PTN users. Unless explicitly stated the terms " network"and "Network Call Control entity" are used interchangeably hereafter. See figure 1.NSAPSAPNSAPSAPCoordinationfunctionsCoordinationfunctionsUserUserNetwork Layer ServiceNetwork CallControl EntitySAP = Service Access PointNSAP = Network Service Access PointFigure 1 - Service ModelSIST ETS 300 171 E1:2005

Page 13ETS 300 171: December 1992The mapping mechanism between NSAPs and Network Call Control service access points is beyond thescope of this Standard. An address which identifies an NSAP also identifies a Network Call Controlservice access point by implication.The primitives used across Network Call Control service access points are as follows.-SETUP_request/indication/response/confirmation; used for call establishment.-RELEASE_request/indication/response/confirmation; used for call rejection and release.-REPORT_request/indication; used for reporting that the called PTN user is being alerted,interworking situations, and the presence of in-band tones or announcements.-INFORMATION_request; used for providing additional destination addressing information notprovided with the SETUP_request.The above primitives are mappable on to the primitives at an NSAP, e.g., N-CONNECT_request/indication/response/confirmation. NSAP primitives relating to the transfer of userinformation do not have equivalents at the Network Call Control service access point.At Stage 1, the control aspects of services are specified in terms of the primitives listed above at theNetwork Call Control service access points. The entire Network Call Control is treated as a single entity.At Stage 2, the internal behaviour of Network Call Control is specified by breaking it down into a number ofFunctional Entities (FE) and specifying the information flows between them. The result is a model of theform shown in figure 2. The particular model used for the basic call is specified in clauses 12, 13, 14, 15and 16. Other models based on this generic model are used for supplementary services. These arespecified in other Standards.NSAPNSAPCoordinationfunctionsCoordinationfunctionsUserUserNetwork Layer ServiceNetwork CallControl EntitySAP = Service Access PointNSAP = Network Service Access PointFEFEFEFESAPSAPFigure 2 - Generic Model for Stage 2.4.6Service AttributesFor each specific service category described in clauses 5 to 8, the attributes, as described in CCITTRecommendations I.140 and I.210, are given. Bearer services are described by low layer attributes.Teleservices are described by both low layer attributes and high layer attributes. High layer attributes areoutside the scope of this Standard.The low layer attributes described in CCITT Recommendation I.210 consist of information transferattributes, access attributes and general attributes. The information transfer attributes define the networkcapabilities for transferring information between PTN users of the service. The access attributes definethe way in which PTN functions are accessed at the S reference point. Access attributes may differ fordifferent PTN users in a call. General attributes are not used in this Standard.SIST ETS 300 171 E1:2005

Page 14ETS 300 171: December 1992Information transfer attributes are subdivided into dominant attributes, defining bearer service categories,and secondary attributes, defining individual bearer services within a category.The dominant information transfer attributes are:i)Information transfer mode;ii)Information transfer rate;iii)Information transfer capability;iv)Structure.The secondary information transfer attributes are:v)Establishment of communication (Note 3);vi)Symmetry (Note 4);vii)Communication configuration (Note 5).The access attributes are:viii)Access channel and rate (Note 6);ix)Access protocols (Note 6).NOTE 3:Only demand services are specified in this Standard. Reserved and permanent services may be thesubject of future Standards.NOTE 4:Only bidirectional symmetric services are specified in this Standard. Unidirectional services may be thesubject of future Standards.NOTE 5:Only point-to-point services are specified in this Standard. Multi-point basic services may be the subject offuture Standards. Multi-point may, however, be provided in conjunction with some bearer servicecategories by means of conference call supplementary services.NOTE 6:The access attributes refer only to the user information, not the signalling information.5.Circuit mode 64 kbit/s unrestricted 8 kHz structured bearer servicecategory5.1DescriptionThis bearer service category provides information transfer at 64 kbit/s without alteration between PTNusers. It may, therefore, be used to support various PTN user applications. Examples include:-speech (Note 7);-3,1 kHz audio (Note 7);-multiple subrate information streams multiplexed into 64 kbit/s by the PTN user;-transparent access to a public or private X.25 network (X.31 case A for access to a public X.25network).SIST ETS 300 171 E1:2005

Page 15ETS 300 171: December 1992NOTE 7:Whilst speech and 3,1 kHz audio have been given as applications for this bearer service, it isrecognised that it is the responsibility of PTN users to ensure that a compatible encoding scheme isin operation. PTN users should also recognise that no network provision can be made for thecontrol of such items as echo and loss, as the network is unaware of the application in use.Furthermore, the quality of service attribute value for information transfer delay indicates thesuitability of a particular version of this bearer service for speech.This circuit mode bearer service category allows:-two PTN users to communicate in a point to point configuration via the network using 64 kbit/sdigital signals, in both directions continuously and simultaneously for the duration of a call;-in conjunction with a conference call supplementary service, three or more PTN users tocommunicate in a multi-point configurationOnce the information channel connection has been established according to the procedures described inclauses 9 to 11, it is available for the transmission of 64 kbit/s digital signals in both directionscontinuously and simultaneously, without alteration by the network. No restriction is placed by the networkon the content of the digital signals.5.2Interworking Considerations5.2.1Interworking with a public ISDNServices in this category are able to interwork with the same services in a public ISDN. The interworkingfunction for user information transfer is null.5.2.2Interworking with networks supporting only a restricted digital information transfercapabilityDuring an interim period, some other networks may only support restricted 64 kbit/s digital informationtransfer capability, i.e., information transfer capability solely restricted by the requirement that the all-zerooctet is not allowed. Interworking can be achieved according to the rules given in Appendix I ofRecommendation I.520 (the PTN being treated as an ISDN with unrestricted 64 kbit/s capability). Theinterworking functions are assumed to be provided in the other network. The PTN is not affected by thisinterworking, other than by conveying the appropriate signalling indication to and from the user.5.2.3Interworking with analogue networksOptionally, the PTN may support calls between data terminals and an analogue network. In this case thefollowing procedures apply.A V-series terminal connected to the PTN via a terminal adaptor and using a 64 kbit/s unrestricted bearerservice requires the use of an interworking function (including a modem) in the PTN for calls to or fromusers of analogue networks, e.g., PSTNs, private analogue networks. To effect the connection a 64 kbit/sunrestricted connection would need to be used to the interworking function, and a 3,1 kHz audio orequivalent connection would then need to be used to the user of the analogue network.NOTE 8:Such an interworking function can be introduced only if additional information concerning layer 1 protocolsis available.In general, when a call originates in an analogue network, the analogue network is unable to indicate tothe PTN the service required. If this is the case, the called PTN user is offered a 3,1 kHz audio bearerservice.SIST ETS 300 171 E1:2005

Page 16ETS 300 171: December 1992NOTE 9:If at the called PTN user there is a terminal adaptor which is unable to accept an incoming 3,1 kHz audiocall but is able to accept an incoming 64 kbit/s unrestricted call, the introduction of an interworking functionin the PTN can be achieved only if there is service negotiation between the PTN and the called terminaladaptor. This capability is outside the scope of this Standard.5.3Service attributes5.3.1Dominant information transfer attributesThe dominant information transfer attributes for this service category are:i)Information transfer mode: circuit;ii)Information transfer rate: 64 kbit/s;iii)Information transfer capability: unrestricted;iv)Structure: 8 kHz integrity.5.3.2Secondary information transfer attributesThe secondary information transfer attribute possibilities for this service category are:v)Establishment of communication: demand / reserved / permanent (Note 10);vi)Symmetry: bidirectional symmetric / unidirectional (Note 11);vii)Communication configuration: point-to-point / multi-point (Note 12).NOTE 10:Only demand services are specified in this Standard.NOTE 11:Only bidirectional symmetric services are specified in this Standard.NOTE 12:Only point-to-point services are specified in this Standard. Multi-point configurations can be achievedusing conference call supplementary services.5.3.3Access attributesThe access attributes (note 13) for this service category are:viii)Access channel: B;ix)Access protocol: Not defined.NOTE 13:The access attributes refer only to the user information not the signalling information.6Circuit mode 64 kbit/s 8 kHz structured bearer service category Usable forspeech information transfer6.1DescriptionThis bearer service category is intended to support speech.User information shall conform to CCITT Recommendation G.711 (A-law or µ-law). The network may useprocessing techniques appropriate for speech such as analogue transmission, echo cancellation and lowSIST ETS 300 171 E1:2005

Page 17ETS 300 171: December 1992bit rate voice encoding. Hence, bit integrity is not assured. This bearer service category is not intended tosupport modem derived voice band data.NOTE 14:A-law encoding is used by public ISDNs in Europe.This circuit mode bearer service category allows:-two PTN users in a point-to-point configuration to communicate in a point to point configuration viathe network using speech encoded into 64 kbit/s digital signals, in both directions continuously andsimultaneously for the duration of a call;-in conjunction with a conference call supplementary service, three or more PTN users tocommunicate in a multi-point configurationOnce the information channel connection has been established according to the procedures described inclauses 9 to 11, it is available for the transmission of speech encoded into 64 kbit/s digital signals in bothdirections continuously and simultaneously. Bit integrity is not assured. The network may use analoguetransmission.Tones and announcements to indicate the progress or otherwise of a call are provided by the network.6.2Interworking Considerations6.2.1Interworking with a public ISDNServices in this category are able to interwork with the same services in a public ISDN. The interworkingfunction for information transfer is null.6.2.2Interworking with analogue networksThis bearer service category is able to interwork with PSTNs and private analogue networks when callsoriginate in the PTN. For calls from an analogue network to the PTN, the analogue network is generallyunable to indicate the service required, and in this case the PTN provides a 3,1 kHz audio bearer servicerather than a speech bearer service, in order to allow for the possibility of voice band data. Calls from thePSTN are always 3,1 kHz audio.6.2.3Encoding law conversionThe PTN can, as an option, provide A-law/µ-law conversion (see CCITT Recommendation G.711) topermit interworking between terminals and interfaces to other networks which do not all conform to thesame encoding law (A-law or µ-law).NOTE 15:Although in general a network which uses µ-law encoding should provide A-law/µ-law conversion wheninterworking with networks which use A-law, this may not apply in the case of a private network using A-law and a public network using µ-law. Therefore even if the PTN uses A-law and expects its terminals andother private networks to use A-law, it may need to provide A-law/µ-law conversion when interworking withpublic networks which use µ-law.6.3Service attributes6.3.1Dominant information transfer attributesThe dominant information transfer attributes for this service category are:i)Information transfer mode: circuit;ii)Information transfer rate: 64 kbit/s;iii)Information transfer capability: speech (encoded)SIST ETS 300 171 E1:2005

Page 18ETS 300 171: December 1992iv)Structure: 8 kHz integrity.6.3.2Secondary information transfer attributesThe secondary information transfer attribute possibilities for this service category are:v)Establishment of communication: demand / reserved / permanent (Note 16);vi)Symmetry: bidirectional symmetric / unidirectional (Note 17);vii)Communication configuration: point-to-point / multi-point (Note 18).NOTE 16:Only demand services are specified in this Standard.NOTE 17:Only bidirectional symmetric services are specified in this Standard.NOTE 18:Only point-to-point services are specified in this Standard. Multi-point configurations can be achievedusing conference call supplementary services.6.3.3Access attributesThe access attributes for this service category are:viii)Access channel: B;ix)Access protocol: CCITT Recommendation G.711 (A-law or µ-law).NOTE 19:The access attributes refer only to the user information, not the signalling information.7Circuit mode 64 kbit/s 8 kHz structured bearer service category usable for3,1 kHz audio information transfer7.1DescriptionThis bearer service category corresponds to the service which is currently offered in the PSTN. It providesfor the transfer of speech and of 3,1 kHz bandwidth audio information such as voice band data viamodems and facsimile groups 1, 2 and 3 information.NOTE 20:The maximum modem bit rate that can be used by PTN users in applications of this bearer servicecategory depends on the modulation standard employed and on the transmission performance of thenetworks involved.User information shall conform to CCITT Recommendation G.711 (A-law or µ-law). The network may useprocessing techniques appropriate for speech, provided they are appropriately modified or functionallyremoved prior
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