1、CCITT RECMN*I.252. 5 92 W 4862593 0573908 T9b INTERNATIONAL TELECOMMUNICATION UNION CCITT THE INTERNATIONAL TELEGRAPH AND TELEPHONE CONSULTATIVE COMMITTEE 1.252.5 (08/92) INTEGRATED SERVICES DIGITAL NETWORK (ISDN) GENERAL STRUCTURE AND SERVICE CA PA B I LIT1 ES CALL DEFLECTION Recommendation 1.252.5
2、 Geneva, I992 CCITT RECMN*I.252. 5 92 m 4Bb2591 0573909 922 m INTERNATIONAL TELECOMMUNICATION UNION CCITT THE INTERNATIONAL TELEGRAPH AND TELEPHONE CONSULTATIVE COMMITTEE 1.252.5 (08/92) INTEGRATED SERVICES DIGITAL NETWORK (ISDN) GENERAL STRUCTURE AND SERVICE CAPABILITIES CALL DEFLECTION Recommendat
3、ion 1.252.5 I - CCITT RECMN*I*252. 5 92 W Y862591 0573910 bYY W FOREWORD The CCIT (the International Telegraph and Telephone Consultative Committee) is a permanent organ of the International Telecommunication Union (ITU). CCIT is responsible for studying technical, operating and tariff questions and
4、 issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The Plenary Assembly of CCIT which meets every four years, establishes the topics for study and approves Recommendations prepared by its Study Groups. The approval of Recommendations by the members
5、 of CCIT between Plenary Assemblies is covered by the procedure laid down in CCIT Resolution No. 2 (Melbourne, 1988). Recommendation 1.252.5 was revised by Study Group I and was approved under the Resolution No. 2 procedure on the 4th of August 1992. l CCIIT NOTES , In this Recommendation, the expre
6、ssion “Administration” is usec for conciseness to indicate both a 1) telecommunication Administration and a recognized private operating agency. 2) A list of abbreviations used in this Recommendation can be found in Annex A. O IT 1992 All rights reserved. No part of this publication may be reproduce
7、d or utilized in any form or by any means, electronic or mechanicd, including photocopying and microfilm, without permission in writing from the ITU. Recommendation 1.252.5 CALL DEFLECTION (revised 1992) 1 Definition Call Deflection permits a served user to, in real time, request that the network re
8、directs an incoming call addressed to the served users ISDN number to another number, The served users originating service is unaffected. Note - In normal situations, the Call Deflection service is provided on a per access basis. (In these situations, there is a one-to-one relationship between ISDN
9、number and access.) However, the network may recognize multiple numbers on a single interface; in addition, it may not understand a complete ISDN number (e.g. Direct-Dialling b) a terminal or terminal user requests call deflection whilst being alerted. In this case, the network shall accept the defl
10、ection request if no other terminal has been connected in the meantime, dependent on the reaction of other terminals to the same call. Two cases are to be distinguished: In either case, if there are several deflection requests, the network will only accept the first request. 2 Recommendation 1.252.5
11、 (OW92) CCITT RECMN*I.252. 5 92 4862593 0573933 353 = If the user has subscribed to the service, the network performs the call deflection towards the indicated number and clears the call to the called (served) user with a positive acknowledgement. Fr call deflection after alerting, the network may e
12、ither: a) b) retain the call to the served user until alerting commences at the deflected-to user; or clear the call to the served user on acceptance of the call defiection request. For call deflection before alerting, only case “b” is applicable. The deflected-to user will receive an indication tha
13、t the call has been deflected. As an option he may also receive: 1) originally called number BI; 2) cause for original diversion; 3) last deflecting number Bx; 4) cause for last deflection. (Depending on the use of other supplementary services, the deflected-to user C may also receive information su
14、ch as the calling party A number and user-to-user signalling. See the descriptions of interactions with other supplementary services.) As a subscription option, the served user can request that the calling user be not notified that deflection has been invoked. In this case, the calling user receives
15、 no information. Also, the served users request that no information be transferred shall override any invocation of Connected Line Identification Presentation (COLP) by the calling user. If the served user requests that the calling user receives notification that the call has been deflected, this in
16、formation may, as an additional option, include the deflected-to number. The following notification procedures for the caliing user A are a network provider option. The notification procedures for calling user A shall only operate if the served user has subscribed to the option “calling user receive
17、s notification that call has been deflected”. For the initial diversion and for any subsequent Call Forwarding No Reply (CFNR), or CD after alerting has commenced, the network will take the following actions depending on the subscription option parameter of the served user. i) If this parameter is s
18、et to “calling user does not receive notification”, no notification is given to the calling user. If this parameter is set to “notify calling user, without deflected-to number”, then the calling user will receive a notification that the cdl has been deflected without the deflected-to number providin
19、g a previous diverting user has not requested that no notification is given as under item 1) above. If this parameter is set to “notify calling user, with deflected-to number”, then the calling user will receive a notification that the call has been deflected, providing a previous diverting user has
20、 not requested that no notification is given as under item 1) above. In addition, if alerting takes place (e.g. at user C), notification of the current deflected-to number will be given when alerting commences if all served users in ail previous diversions subscribe to “notify calling user, with def
21、lected-to number”. 2) 3) Transfer of the deflected-to users number may be subject to number notification restrictions due to invocation of other supplementary services at the deflected-to user. 3.3 Exceptional procedures 3.3.1 Activutioddeuctivutiodregistrution Not applicable. Recommendation 1.252.5
22、 (08/92) 3 - -_ _ CCITT RECMN*I-252- 5 92 W 4862593 O573934 29T W 3.3.2 Invocation and operation In cases where a user may be given the address of users involved in the call e.g. when the calling user may receive the deflecte-to users address, or when the deflecte-to user may receive the deflecting
23、users address and originally deflecting address (multiple diversions), or when the served user may receive users addresses as part of that users notification and this address information is unavailable (e.g. due to address presentation restriction or interworking), the user who would have been given
24、 the address shall get an indication on the reason why no number can be given. Within the ISDN or tandem ISDNs the total number of all diversions for each call should be limited. The maximum number of such connections should be limited to a value between three and five. This is to prevent infinite l
25、ooping. If the system cannot accept a deflection request, the served user should receive a notification that deflection i) service not subscribed; ii) deflected-to ISDN number invalid; iii) use of an operator access prefix; iv) deflected-to ISDN number telecommunications service violates subscribed
26、constraints (e.g. group restrictions); v) deflected-to ISDN number is of a free number within the same office; vi) insufficient information; vii) requested telecommunications service is not provided to the deflected-to ISDN number; viii) deflected-to number is a special service code (e.g. police); i
27、x) deflected-to number is served users number; x) limit of tandem diverting connections reached. However, the network is not required to validate information related to the deflected-to user. If the deflected call cannot be completed to the deflected-to destination, then, as a network option, the ne
28、twork may either: a) continue the call at the deflecting user. Note that with this option, if alerting at the deflecting user had begun, then alerting would not be interrupted; or b) clear the call towards the calling user and send an indication that the call cannot be completed. This indication sha
29、ll not explicitly reveal that the call has been forwarded. If CFNR or CD after alerting has previously occurred, then the call would be cleared back towards that served user; refer to Recommendations 1.252.3 or 1.252.5 respectively, for these cases. is unsuccessful. Possible causes are: For call def
30、lection before alerting, only case “b” is applicable. 3.4 Alternate procedures 3.4.1 Activutioddeactivatiodregistration None identified. 3.4.2 Invocation and operation None identified. 4 Network capabilities for charging This Recommendation does not cover charging principles. Future Recommendations
31、in the D-Series are expected to contain that information. It shall be possible to charge the subscriber accurately for the service. 4 Recommendation 1.252.5 (OW92) CCITT RECMN*I.252. 5 92 4b2591 0573715 126 W 5 Interworking requirements With diversion invoked across more than one network, e.g. from
32、public switched telephone network (PSTN) via ISDN to another PSTN or between ISDNs of different countries, or even different continents, a decrease in Quality of Service parameters may arise. For example, the parameters that may be influenced are: - Call Establishment Time; - Transmission Delay; - B
33、it Error Ratio; - Attenuation of Audio Signals. Depending on national implementations, the network may provide some precautions, e.g. limit the number of forwarding legs, limit the number of international border crossings, limit the number of satellite hops, etc. 5.1 Interworking with non-ISDN netwo
34、rks If the deflected-to number is not within the ISDN, then an interworking situation is said to exist. The number of times a call will be deflected once it has exited the ISDN network cannot be limited by this ISDN network. If a deflected call meets an interworking situation, then an interworking i
35、ndication should be sent to the calling party. This indication shaii not explicitly reveal that the call has been deflected. In case of interworking, appropriate tones and/or announcements should be provided. Note - Once a call has been deflected to a non-ISDN network, then further diversions and/or
36、 notifications to the calling user are outside the scope of this Recommendation. 5.2 Interworking with private ISDNs Within ISDNs (public or private) the total number of diversions for each call should be limited (see 0 3.3.2). Where a remote user is on a different network, notifications to the remo
37、te user, if applicable, shall be sent to the remote users network for forwarding to the remote user. If the private network detects deflection back to a destination in the public network, the private network could request that deflection is performed by the public network. This assumes cooperation b
38、etween the public and private networks. The private network may also optionally specify either a transit network or a network specific facility, or both, to be used for that deflection. If 8 private ISDN employs other types of service interactions than specified under 6 6, e.g. with completion of ca
39、lis to busy subscribers (CCBS), the private ISDN shall supply the necessary precautions against such consequences. 6 Interaction with other supplementary services The ways in which cali deflection interacts with other supplementary services are in general identical to the ways in which Call Forwardi
40、ng Unconditional interacts with other supplementary services. Thus, if the interactions are described to be “Same as Call Forwarding Unconditional (FU)”, the CF text should be taken verbatim, except that the words “call forwarding unconditionai” should be replaced with “call deflection”, Recommendat
41、ion 1.252.5 (08/92) 5 CCITT RECMN*I=252. 5 92 m 4862591 057391b Ob2 m 6.1 Call Waiting Calling user: Same as CF (see Recommendation 1.252.4). Called user: CD can be used in response to a cai1 waiting indication. Defected-to user: A deflected call can invoke call waiting. 6.2 Call Transfer Same as CF
42、U (see Recommendation 1.252.4). 6.3 Connected Line Identification Presentation Calling user notification of the diverted-to number is part of the diversion service and should not be considered to require an invocation of COLP by the calling user. If the served (diverting) user selects the option tha
43、t the calling user is not notified of call deflection, then the calling user will receive no deflection notification. In addition, the calling user will not receive the connected users identity when the call is answered, unless the calling user has override capability. If the served (diverting) user
44、 selects the option that the calling user is notified, but without the deflected-to number, then the calling user will not receive the connected users identity when the call is answered, unless the calling user has override capability. 6.4 Connected Line Identijkation Restriction If a deflected-to u
45、ser subscribes to Connected Line Identification Restriction (COLR) “permanent mode”, then the deflected-to users number shail not be provided with the notification that the call has been deflected. If a deflected-to user subscribes to COLR “temporary mode”, the provision of the deflected-to users nu
46、mber to the calling user shall not be dowed during the alerting conditions of the call. The deflected-to users connected number may still be provided on answer, based on COLR temporary mode operation. In each of the above situations, a calling user that subscribes to COLP and having override capabil
47、ity, shall not be able to receive the deflected-to user number as part of the diverting notifcation information, but can invoke COLP in order to receive the connected line identity when the call is answered. 6.5 Calling Line Identication Presentation Scatne as CFU (see Recommendation 1.252.4). 6.6 C
48、alling Line Identcation Restriction Same as CF (see Recommendation 1252.4). 6.7 Closed User Group Closed User Group (CUG) restrictions between the calling user and the deflecting user must be met. In the case of multiple diversions, CUG restrictions between the calling user and the diverting user ha
49、ve to be met at each intermediate diverting point. In addition, CUG restrictions between the calling user and diverted-to user must be met end-to-end. Called useddiverted-to user: When a call is diverted, a new check of the CUG restrictions between the calling user and diverted-to user is made at the “diverted-to” destination. The CUG information sent to the “diverted- to” destination is the same calling user CUG infomation that was sent from the originating network. 6 Recommendation 1,252.5 (08/92) CCITT RECMNxI.252. 5 92 W 4862591 0573917 TT9 6.8 Conf
