1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 ) TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU).4%2!4%$G0G03%26)#%3G0G0$)4!,G0G0.%47/2+G0 )3$.G93%26)#%G0G0#!0!“),)4)%3G0 G0“%!2%2G0G03%26)#%33500/24%$G0G0“9G0G0!.G0G0)3$.#)2#5)4G13-/$%G0G0“%!2%2G0G03%26)#%#!4%/2)%3G0G0 G0G0#)2#5)4G13-/$%G0G0 G0KBIT S G0
2、K(ZG0G03425#452%$G0G0“%!2%2G0G03%26)#%53!“,%G0G0- three or more users in a multipoint configuration (refer to Recommendation I.254 for the supplementaryservice description for Three-Party Service and Conference Calling).Tones and/or announcements to indicate the progress or otherwise of a call, are
3、provided by the network.2.2.2 Specific terminologyRetention timer: this timer specifies the amount of time that the network retains the call information of theoriginal call upon encountering busy or being released. It is a network provider option. The value for this timer isgreater than 15 seconds.2
4、.3 Procedures2.3.1 Provision/withdrawal2.3.1.1 Provision of this service will be by pre-arrangement with the Administration.2 Fascicle III.7 - Rec. I.231.22.3.1.2 This bearer service is offered with several subscription options which apply separately to each ISDN numberor group of ISDN numbers on th
5、e interface. For each subscription option, only one value can be selected. Subscriptionoptions for the interface are summarized below:Subscription option ValueMaximum number of informationchannels available at user BMaximum number of total callspresent at user B- m, where m is not greater than thenu
6、mber of information channels onthe interface- n, where n is not greater than thenumber of information channels onthe interfaceUser B can be an ISDN number or group of ISDN numbers on the interface.Note - More than one ISDN number can be associated with the service/interface only as a part of asupple
7、mentary service such as multiple subscriber number. In the case of one ISDN number, the option given above forthe number of calls can only exceed the number of information channels in association with a supplementary service(e.g. call waiting). As a network provider option, separate values may be sp
8、ecified for incoming and for outgoing callsfor either or both of the limits.2.3.2 Normal proceduresOut-of-band messages shall always be provided to indicate call progress, etc. However, network-generated in-band tones and announcements shall always be provided for this bearer service category.a) Ori
9、ginating the service (call set-up)The call is originated by the user requesting the required bearer service; the request includes a numberidentifying the called user. Other information, as required, for the bearer service and for use by thenetwork in supplementary services provided to the called use
10、r (e.g. calling line identity) may also beincluded. This request may be given to the network either en bloc, containing all the requiredinformation, or not en bloc.b) Indications during call set-upAll indications entail signalling messages and shall include, where appropriate, in-band tones orannoun
11、cements.After initiating a call the calling user will receive an acknowledgement that the network is able to processthe call. The called user will receive an indication of the arrival of an incoming call of this bearer service.The calling user shall also be given an indication that the incoming call
12、 is being offered to the calleduser, when an indication is received by the network that the called user is being informed of this call.When the call reaches the called user and the connection is established, an indication of this is sent to thecalling user.The called user may also provide other info
13、rmation for use by the network in supplementary servicesprovided to other users (e.g. connected line identity). The relationship of a connected user with a calleduser requires further study.Once established, the B-channel is then available for the transmission of speech signals in both directionscon
14、tinuously and simultaneouslyc) Terminating the callThe call may be terminated by either or both of the users by indicating this to the network. If one userterminates the call, an appropriate indication is sent to the other user.Fascicle III.7 - Rec. I.231.2 32.3.3 Exceptional proceduresa) Failure si
15、tuations due to user errori) A user inputting a network-identifiable, improper service request will be given an appropriatefailure indication by the network and the call set-up will be ceased.ii) A user inputting a non-valid network number will be given an appropriate failure indication by thenetwor
16、k and the call set-up will be ceased.b) Failure situations due to called user statei) A calling user attempting to establish a call to a user who is identified by the network to be busy(either network-determined user busy or user-determined user busy) will be given an appropriatefailure indication b
17、y the network.ii) A user attempting to establish a call to a user whose terminal equipment fails to respond will begiven an appropriate failure indication by the network and the call set-up will be ceased.iii) On a call to a user whose terminal equipment has responded that the called user is being i
18、nformedof the call but has failed to answer within a defined period of time, the calling user attempting toestablish the call will be given an appropriate failure indication by the network and the call-set upwill be ceased.c) Failure situations due to network conditionsA user attempting to establish
19、 a call but meeting call failure situations due to network conditions (e.g.,congestion) will be given an appropriate failure indication by the network.d) Failure situations due to called user state and/or network conditionsA user attempting to establish a call but meeting call failure situations due
20、 to network conditions (e.g.congestion) or called user state (e.g. busy) can have service data retained for a specified period of time,i.e. retention timer.2.3.4 Alternative procedures2.3.4.1 Reserved service proceduresFor further study.2.3.4.2 Permanent service proceduresFor further study.2.4 Netwo
21、rk capabilities for chargingThis Recommendation does not cover charging principles. Future Recommendations in the D-Series areexpected to contain that information.2.4.1 Demand service chargingIt shall be possible to charge the subscriber accurately for the demand service.2.4.2 Reserved service charg
22、ingIt shall be possible to charge the subscriber accurately for the reserved service.2.4.3 Permanent service chargingIt shall be possible to charge the subscriber accurately for the permanent service.2.5 Interworking requirementsInterworking is required between the ISDN and the PSTN for this bearer
23、service category.4 Fascicle III.7 - Rec. I.231.22.6 Interaction with supplementary servicesNot applicable. Each supplementary service description identifies the applicability with this bearer servicecategory.2.7 Attributes and values of attributes of the circuit-mode 64 kbit/s 8 kHz structured beare
24、r service categoryusable for speech information transferInformation transfer attributes1. Information transfer mode: circuit2. Information transfer rate: 64 kbit/s3. Information transfer capability: speech (encoded according to Recommendation G.711 A-law,-law) (Note 1)4. Structure: 8 kHz integrity5.
25、 Establishment of communication: demand/reserved/permanent6. Symmetry: bidirectional symmetric/unidirectional7. Communication configuration: point-to-point/multipointAccess attributes8. Access channel: B for user information,D for signalling (Note 2)9. Access protocol: I-Series for D-channel, Rec. G
26、.711 for B-channelGeneral attributes10. Supplementary services provided - Refer to Recommendation I.25011. Quality of Service 12. Interworking possibilities for further study (may be13. Operation and commercial aspects different from I.231.1)Note 1 - When crossing an international boundary between A
27、dministrations which employ different encodinglaws, the network shall perform the necessary A- law conversion (see Recommendation G.711).Note 2 - For reserved/permanent service the operational administrative and maintenance (OAM) messagesrelated to these services may be conveyed over the D-channel.F
28、ascicle III.7 - Rec. I.231.2 52.8 Provision of individual circuit-mode 64 kbit/s, 8 kHz structured bearer services usable for speech informationtransfera) Overall provision1): ENote - Some networks will offer this service in a manner identical to the 3.1 kHz audio service.b) Variations of secondary
29、attributes:Establishment Symmetry Communication Provision1)of communication of configurationI.231.2/1 demand pt-pt EI.231.2/2 reserved bidirectional pt-pt AI.231.2/3 permanent pt-pt EI.231.2/4 demand pt-pt AI.231.2/5 reserved unidirectional pt-pt AI.231.2/6 permanent pt-pt AI.231.2/7 demand multipt
30、AI.231.2/8 reserved bidirectional multipt AI.231.2/9 permanent multipt AI.231.2/10 demand multipt AI.231.2/11 reserved unidirectional multipt AI.231.2/12 permanent multipt Ac) AccessSignalling and OAM (Note 1) User information ProvisionChannel and rate Protocols Channel and rate ProtocolsD(16)D(64)I
31、.451 (Note 2)I.451 (Note 2)B(64)B(64)G.711G.711EENote 1 - Definition of protocols for OAM is for further study.Note 2 - Demand services only. Further study for reserved and permanent services.2.9 Dynamic descriptionThe dynamic description for this service on a demand basis is identical for a number of circuit mode servicesand is therefore collectively given in Recommendation I.220._1)The definition of E (essential) and A (additional) can be found in Recommendation I.230.
