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 thesupplementary service descriptions on 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.3.2.2 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、 Fascicle III.7 - Rec. I.231.33.3 Procedures3.3.1 Provision/withdrawal3.3.1.1 Provision of this service will be by pre-arrangement with the Administration.3.3.1.2 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.3.3.2 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.a) Originating
9、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 user (e.g. c
10、alling 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 may also include in-band tones or announcements.After initiating
11、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 is being offered to the
12、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 information for use by the ne
13、twork 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 the requested (i.e. speech or3.1 kHz audio information) signa
14、ls in both directions continuously and simultaneously.Fascicle III.7 - Rec. I.231.3 3c) 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.3.3.3 Exception
15、al proceduresa) Failure situations 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 failu
16、re indication by thenetwork 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 appro
17、priatefailure indication by 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
18、the called user is being informedof 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 us
19、er attempting to establish 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 ca
20、ll failure situations due 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.3.3.4 Alternative procedures3.3.4.1 Reserved service proceduresFor further study.3.3.4.2 Permanent service proceduresF
21、or further study.3.4 Network capabilities for chargingThis Recommendation does not cover charging principles. Future Recommendations in the D-Series areexpected to contain that information.3.4.1 Demand service chargingIt shall be possible to charge the subscriber accurately for the demand service.3.
22、4.2 Reserved service chargingIt shall be possible to charge the subscriber accurately for the reserved service.4 Fascicle III.7 - Rec. I.231.33.4.3 Permanent service chargingIt shall be possible to charge the subscriber accurately for the permanent service.3.5 Interworking requirementsInterworking i
23、s required between the ISDN and the PSTN for this bearer service category.3.6 Interaction with supplementary servicesNot applicable. Each supplementary service description identifies the applicability to this bearer servicecategory.3.7 Attributes and values of attributes of the circuit-mode 64 kbit/
24、s, 8 kHz structured bearer service categoryusable for 3.1 kHz audio information transferInformation transfer attributes1. Information transfer mode: circuit2. Information transfer rate: 64 kbit/s3. Information transfer capability: 3.1 kHz audio (Note)4. Structure: 8 kHz integrity5. Establishment of
25、communication: demand/reserved/permanent6. Symmetry: bidirectional symmetric/unidirectional7. Communication configuration: point-to-point/multipointAccess attributes8. Access channel: B for user information, D for signalling and/or operational,administrative and maintenance (OAM) messages9. Access p
26、rotocol: Recommendation G.711 for B-channel, I-Series for D-channelGeneral attributes10. Supplementary services provided - Refer to Recommendation I.25011. Quality of Service 12. Interworking possibilities for further study13. Operation and commercial aspects Note - When crossing an international bo
27、undary between Administrations which employ different encodinglaws the network shall perform the necessary A- law conversion (see Recommendation G.711).Fascicle III.7 - Rec. I.231.3 53.8 Provision of individual circuit-mode 64 kbit/s, 8 kHz structured bearer services usable for 3.1 kHz audioinformat
28、ion transfera) Overall provision1): Eb) Variations of secondary attributes:Establishment Symmetry Communication Provision1)of communication of configurationI.231.3/1 demand pt-pt EI.231.3/2 reserved bidirectional pt-pt AI.231.3/3 permanent pt-pt EI.231.3/4 demand pt-pt AI.231.3/5 reserved unidirecti
29、onal pt-pt AI.231.3/6 permanent pt-pt AI.231.3/7 demand multipt AI.231.3/8 reserved bidirectional multipt AI.231.3/9 permanent multipt AI.231.3/10 demand multipt AI.231.3/11 reserved unidirectional multipt AI.231.3/12 permanent multipt Ac) AccessSignalling and OAM (Note 1) User information Provision
30、Channel rate Protocols Channel and rate ProtocolsD(16)D(64)I.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.3.9 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.
