1、CEPT T/CS*ZL-O*E 4 E 2326434 0004620 5 Page 1 TCS21-08 E Recommendation T/CS 21-08 (Montpeuier 1984) CALL HANDLING SEQUENCES FOR DIVERSION OF TELEPHONE CALLS TO ANOTHER NUMBER Recommendation proposed by Working Group T/WG 11 “Switching and Signalling”(CS) Text of the Recommendation adopted by the “T
2、elecommunications” Commission: “The European Conference of Postal and Telecommunications Administrations, considering - that supplementary services which imply diversion of telephone calls to another number are subject to harmonisa- tion; - that the operational requirements for a number of such supp
3、lementary services are dened in the “Handbook on services and facilities offered to the subscribers in modern telephone systems” l; - that the operation of those services requires the utilization of the “additional signalling feature” as dened in Recommendation T/CS 20-26 2; . - that an appropriate
4、way of specifying additional signalling information and its flow is by means of call handling sequence charts, according to Recommendation T/CS 21-01 3; - that the defnitions, arrangements and basic technical specifications for diversion of caiis are given in Recommen- dation T/CS 20-25 4; - that th
5、e operation of supplementary services as mentioned above should be possible across country borders; - that a rapid implementation of those supplementary services requires a less enhanced form of caii handling suited O for implementation with existing signalling systems, recommends to members of the
6、CEPT to adopt for the provision of supplementary services which imply diversion of telephone calk to another number the call handling sequences as depicted below for the “call forwarding” and “rerouting” type of diversion, depending on transmission, signalling and charging aspects.” Edition of May 1
7、5, 1986 CEP“ T/CS*21-O*E 4 E 2326414 0004b21 7 W T/CS 21-08 E Page 2 1. 1.1. 1.2. 1.3. 1.4. 1.5. 1.6. 1.6.1. 1.6.2. 1.6.3. 1.6.4. 1.7. 1.7.1. 1.7.2. 1.7.3. 1.7.4. GENERAL STATEMENTS Basis concepts The definitions, arrangements and basic technical specifications for diversion of calls, as given in Re
8、com- mendation T/CS 20-25 4, apply. Class marking of diverted cails A call which is diverted due to an activated supplementary service should be marked at call set-up as a diverted call. Note: This class marking may be omitted if the network part concerned cannot provide the required additional sign
9、alling to convey fhe classmark. In this case, however, multiple diversion cannot be inhibited. No c.verted telephone call allowed at C When diverted telephone calls are not allowed to arrive at the C-subscribers network termination (e.g. because the C-subscriber has activated a supplementary service
10、 affording diversion of telephone calls to another number and no second diversion is allowed), then diversion to an appropriate audible indication should occur. C-destination invalid or incompatible If the C-destination is found invalid or incompatible at the A-side of the call, then the same call h
11、andling principles as mentioned at paragraph 1.3. should be applied. C-destination busy or congestion underway If the C-destination is found busy or the call to the C-destination meets congestion, then the diverted call schould be treated as a.normal call meeting busy or congestion respectively. Cha
12、rging of diverted calls The following methods of charging of diverted calls have been identied: (a) Subscriber A is charged as for a normal call A-C, subscriber B is not charged. (b) Subscriber A is charged as for a normal call A-B, subscriber B is charged either as for a normal call B-C or at a spe
13、cial rate, depending on A and/or C. In the case of existing networks which apply call forwarding, method (b) of paragraph 1.6.1. with the normal call rate for subscriber B is advantageous, as no additional signalling is required with respect to charging. The call handling sequences and service instr
14、uctions necessary to implement charging method (b) for call diversion by means of rerouting still require further study. The case of A- and B-subscriber belonging to different networks (e.g. international relation) in which different methods of charging of diverted calls are applied, still requires
15、further study as well. Methods of call diversion Call diversion may be carried out in either of the following ways (see Recommendation T/CS 20-25 4): (a) by means of call forwarding; (b) by means of rerouting (controlled by the A-exchange or by an intermediate exchange). Which of the two methods is
16、used is primarily decided by the B-exchange. The B-exchange may be programmed in either of the following ways: (a) for each diversion, call forwarding is applied; (b) depending on the location of A- and C-subscriber, a decision is taken to divert a given call either by means of rerouting or by means
17、 of call forwarding; (c) the B-exchange always first tries to reroute a call which is subject to diversion. Other criteria for choosing between call forwarding and rerouting may be applied, e.g. information about the signalling capability on the call path A-B. The use of these criteria requires furt
18、her study. In order to know the location of A, an ANI-procedure may be carried out by the B-exchange. In the case of rerouting, the service instructions to reroute a call may be handled either by the A-exchange or by an intermediate exchange, depending on the location of A and C. (For instance, in t
19、he case of an international incoming call, the rerouting could be performed by the incoming international exchange.) - _ Edition of May 15, 1986 CEPT T/CS*ZL-OB*E 84 2326414 0004622 9 W 1.7.5. 2. 3. 3.1. 3.2. 3.3. 3.4. TICS 21 -08 E Page 3 If the A- or I-exchange to which the SI for diversion has be
20、en sent cannot control the rerouting or finds it inappropriate (e.g. for charging reasons), a general negative acknowledgement SI should be sent to the B-exchange. The latter may decide now to divert the call by means of call forwarding. If this is found impossible or inappropriate, a suitable audib
21、le indication should be sent to the caller. SUPPLEMENTARY SERVICES CONSIDERED FROM SF-HANDBOOK Service 4.1.1. : Service 4.1.2. : Service 4.1.3.: Service 4.1.13.: Service 4.1.14.: Service 4.1.15. : Service 6.3.4.: Service 6.3.5.: Service 6.3.7.: Service 6.3.8.: Absent subscriber service, immediate di
22、version, to a manual answering service. Absent subscriber service, immediate diversion, to one number of a predetermined group. Absent subscriber service, immediate diversion, to any number. Absent subscriber service, diversion on no reply, to a manual answering service. Absent subscriber service, d
23、iversion on no reply, to one number of a predetermined group. Absent subscriber service, diversion on no reply, to any number. Diversion on busy, administration registration, subscriber control, to one number of a predetermined group. Diversion on busy, administration registration, to the rst availa
24、ble number in a se- quence. Diversion on busy, fully subscriber controlled, to the rst available number in a se- quence. Diversion on busy, fully subscriber controlled, to any number. CALL HANDLING SEQUENCE CHARTS The following call handling sequence charts have been provided : 1. Diversion by means
25、 of call forwarding. 2. Diversion by means of rerouting. Both call handling sequence charts have the following structure: - initial sequences for immediate diversion, diversion on no reply and diversion on busy; - general sequence for call forwarding and rerouting respectively; - special sequences f
26、or the cases that the B-subscriber answers within the time-out for diversion on no reply, C-destination unacceptable at A-exchange (for rerouting only), congestion between A and Cy C-subscriber busy and diverted calls unacceptable to C-subscriber; - general diverted call failure sequence. The call h
27、andling sequence chart for diversion by means of rerouting is drawn for the case that the rerouting is controlled by the A-exchange. in the case that the rerouting is controlled by an intermediate exchange, the same call handling principles should be applied. The call handling.sequences for call for
28、warding have been designed in such a way that no additional signalling is necessary on the connection A-B. Edition of May 15, 1986 v CEPT T/CS*ZL-O*E 4 2326414 0004623 O A-exchange TICS 21-08 E Page 4 B-exchange C-exchange Call handling sequence chart 1: diversion by means of call forwarding RNR O 1
29、0 20 30 ,40 50 60 70 80 90 1 O0 200 210 220 230 240 250 INITIAL SEQUENCE FOR IMMEDIATE DIVERSION Normal call set-up procedure * Line service marking of B-subs. contains: “Immediate diversion to C activated.” B-subscribers line state is not tested nor changed. If ANI not necessary continue at RNR 70.
30、 ANI request 4 I ANI (complete or partly) Call forwarding from A to C is found acceptable or Note 2. Address complete - Time-out on answer is started. I Continuation with General call forwarding sequence (RNR GOO) INITIAL SEQUENCE FOR DIVERSION ON NO REPLY I Normal call set-up procedure Line service
31、 marking does not contain: “Immediate diversion to any C activated.” B-subs. is found free or Note 6. Line service marking of B-subs. contains: “Diversion on no reply to C activated.” If ANI not necessary continue at RNR 280. Note 1 2 15 RNR A-exchange 260 270 280 290 300 310 320 330 340 350 360 B-e
32、xchange 400 410 420 430 440 CEPT T/CS*ZL-OB*E 84 2326414 0004b24 2 TICS 21-08 E Page 5 Call handling sequence chart 1: diversion by means of call forwarding ANI (complete or partly) Address complete Y Call arrival signal I Ringing tone +- - rime-out on answer for normal call is started. Time-out on
33、answer for diversion on no reply is started. Time-out on answer for diversion on no reply expires or RNR 800. Call forwarding from A to C is found acceptable or Note 3. Call arrival signal and ringing tone are withdrawn. B-subscriber is marked “free”. C-exchange Continuation with General call forwar
34、ding sequence (RNR 600) INITIAL SEQUENCE FOR DIVERSION ON BUSY I Normal call set-up procedure Line service marking does not contain: “Immediate diversion to any C activated.” B-subs. is found busy. Line service marking of B-subs. contains: “Diversion on busy to C activated.” Edition of May 15, 1986
35、Note 5 CEPT T/CS*23-O8*E 84 m 2326434 0004625 4 m A-exchange TICS 21 -08 E Page 6 B-exchange Call handling sequence chart 1: diversion by means of call forwarding Time-out on answer for call B-C is started. -_ I If ANI not necessary continue at RNR 480. ANI request Time-out on answer is removed. Y I
36、 ANI (complete or partly) Time-out on answer is removed. r Call forwarding from A to C is found acceptable or Note 4. Address complete 4 Time-out on answer is started. I C-exchange Continuation with General call forwarding sequence (RNR 600) GENERAL CALL FORWARDING SEQUENCE (Continuation from RNRs 1
37、00, 360 and 510) Diverted call B-C is marked. Optional : Announcement about diversion f - - - - - - - - - - - - - Normal call Set-up procedure + S.I. “diverted call” Note 1 4 15 16 8 9 17 10 Edition of May 15, 1986 CEPT T/CS*2L-OB*E 84 m 2326414 0004626 b m Start charging of subs. A for call A-B. RN
38、R Start charging of subs. B. 720 130 END Time-out on answer for normal call (started at RNR 300) is removed. Start charging of subs. A for normal call A-B. 800 810 820 830 840 END Time-out on answer for diversion on no reply (started at RNR 300) is removed. 900 910 920 1000 1010 1020 1100 1110 1120
39、TICS 21 -08 E Page 7 Cali handling sequence chart 1: diversion by means of call forwarding I C-exchange I A-exchange B-exchange WJBSCRIBER ANSWERS WITHIN TIME-OUT FOR DIVERSION ON NO REPLY (Alternative continuation from RNR 320) Continuation as for normal call A-B in answered condition END CONGESTIO
40、N BETWEEN B AND C (Alternative continuation from RNR 630) I Congestion Continuation with General diverted call failure sequence (RNR 1200) C-SUBSCRIBER BUSY (Alternative continuation from RNR 640) Called prty busy 4 I Continuation with General diverted call failure sequence (RNR 1200) DIVERTED CALLS
41、 UNACCEPTABLE TO C-SUBSCRIBER (Alternative continuation from RNR 650) I I Diverted call unacceptable 4 Continuation with General diverted call failure sequence (RNR 1200) Edition of May 15, 1986 - Note 11 12 CEPT T/CS*2L-O*E 4 2326434 0004627 TICS 21-08 E Page 8 Caii handling sequence chart 1: diver
42、sion by means of caii forwarding RNR 1230 1240 1250 END 200 210 220 A-exchange B-exchange C-exchange GENERAL DIVERTED CALL FAILURE SEQUENCE (Continuation from RNRs 920, 1020 and 1120) Normal clear procedure b The marking of the diverted call B-C is removed. No next C-number available or Note 13. App
43、ropriate audible indication +- I Clear Sig Normal clear procedure - bb END Note 13 14 Edition of May 15, 1986 CEPT T/CS*ZL-O*E 4 = 2326434 0004b2 T TICS 21 -08 E Page 9 Notes to call handling sequence chart 1 1. The ANI sequence is optional; it may be needed for the calculation of the charge and/or
44、to determine if call forwarding is 2. If immediate diversion cannot occur for reasons found by the B-exchange then the incoming Cal should be diverted to an 3. If diversion on no reply cannot occur for reasons found by the B-exchange then the incoming call should be dealt with as a 4. If diversion o
45、n busy cannot occur for reasons found by the B-exchange then the incoming call should be treated as if B were 5. If “immediate diversion to any subscriber” has been activated for the B-subscriber, then “diversion on no reply” and “diversion 6. If the B-subscriber is busy with “diversion on no reply”
46、 activated then the call should be treated as a normal call to a busy 7. The time-out on answer for diversion on no reply should be significantly shorter than the time-out for normal calls as applied 8. In unenhanced network parts, the SI “diverted call” may be omitted: see the Note at paragraph 1.2
47、. of the General statements. 9. Optionally, a special call arrival signal may be sent to the C-subscriber instead of the normal call arrival signal. 10. If the time-out answer in A- or B-exchange expires before the C-subscriber has answered, then all relevant call paths should 11. At clearance of th
48、e call, the marking of the diverted call B-C in the B-exchange should be removed. 12. For uniformity reasons also in the case that the C-subscriber has activated “diversion on no reply” and no multiple diversion is allowed, the condition “diverted call unacceptable” will apply at the moment when an
49、incoming diverted call arrives for the C-subscriber and not after expiry of the time-out for diversion on no reply. 13. In the case that a next C-number is available (which is possible only at supplementary services nrs. 6.3.5. and 6.3.7.) a diverted call to the next number in the sequence should be set up as from RNR 600. If all numbers have been tried without success then the sequence from RNR 1240 should be applied. The announcement about diversion specified at RNR 620 should, however, not unnecessarily be repeated
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