1、- Page 1 22-08 E - Recommendation T/S 22-08 dinburgh 1988) COMPLETION OF CALLS TO BUSY SUBSCRIBER SERVICE Recommendation proposed by Working Group T/WG 11 “Signalling, Protocols and Switching” (SPS) Text of the Recommendation adopted by the “Telecommunications” Commission: “The European Conference o
2、f Postal and Telecommunications Administrations, consderirig - the available service description on Completion of Calls to Busy Subscriber (CCBS) (Stage 1) in CEPT - that in accordance with the principles outlined in Recommendation T/SPS 20-01 E the Exchange and Network Features which are required f
3、or the implementation of services and facilities should be identified and specified, - that in several CEPT member countries supplementary services will be offered which imply that call attempts which are unsuccessful due to the called party being busy will be automatically coinpleted, when the call
4、ed party becomes free, - that it is desirable to handle such calls in a standardized way especially, when these calls are crossing borders, T/SF 31-07 E, recommends that the CEPT members recognize and use the following definitions, arrangements, and specifications for the Supplementary Service Compl
5、etion of Calls to Busy Subscriber.” i b Edition of October 31, 1989 .- I 2326434 0007880 2 TIS 22-08 E Page 2 - - 1, 2. 2,1, 2.2. 2.3. 3. 3.1. 3.2. GENERAL This Recommendation contains the Stage 2 description for the Completion of Calls to Busy Subscriber Service. DESCRIPTION General Description Com
6、pletion of Calls to Busy Subscriber allows a calling user A, encountering a busy destination B, to be notified when the busy destination B becomes not busy and to have the service provider reinstate the call to the specified destination B, if user A desires. Specific Terminology None identified. Qua
7、lifications on the Applicability to Telecommunications Services This supplementary service is applicable to all telecommunications services, however, this Recommendation is limited to circuit switched telecommunications services. The applicability to other telecommunications services is for further
8、study. DESCRIPTION OF THE FUNCTIONAL MODEL Functional Model for the CCBS Service FE1 ?Originating Service Agent? (OSA) FE2 ?Originating Service Controlling Functional Entity? (OCE) FE3 ?Terminating Service Controlling Functional Entity? (TCE) FE4 ?Terminating Service Agent? (TSA) OSA OCE TCE l?SA -
9、rl Figure 1 (TIS 22-08). Service Functional Entity Model. Relationship to the Basic Services Figure 2 (T/S 22-08). Relationship between the CCBS Service and the Basic Services. if 7 Edition of October 31, 1989 = 2326434 0007883 4 =I . TIS 22-08 E Page 3 4. INFORMATION FLOWS 4.1. Information Flow Dia
10、grams n n n m (B J a, (B J O o a, U a, (B O a, a, L (B n 2 %-I w“ G E O L 9- 3 3 D o o (B D .I+ n a u U a, 4 a, U o -* a, o c O a a m n d d 2 O o cn u u m .c QI 3 VI C U 8 I I 1 I I ai i J U ai o O L O O E L O C 2 i3 (B O u 2 2 O i 4 C O o A Edition of October 31, 1989 TIS 22-08 E Page 4 - El datus
11、req . compat. and , busy I , notify: E free I 232b414 0007882 b E I notify CCBS cancelled Case: A busy when B becomes free, no optional deffering of CCBS. Edition of October 3 1 (-“- 2326434 0007883 8 m: TIS * W G I a c O a, a, L + + m 4 cn u u m cn u u a, E J (D a, c m A 0- I. U w“ G Edition of Oct
12、ober 31, 1989 E 2326434 0007884 T TIS 22-08 E Page 6 4.2. Functional Entity Interactions The following information is required to be included in the functional entity interactions: FE2 TO FE3 “Request CCBS” - ISDN number of A + subaddress if any. - ISDN number of B + subaddress if any. - Bearer serv
13、ice. - Teleservice. - Subscriber category for A. - No information. - Normal call Set-up with the additional information that the call is a CCBS call. Possible additional information is a reference to the CCBS function. “Cancel from A” “CCBS call Set-up” “A-answer - No information. FE3 TO FE2 “CCBS a
14、ccepted” - No information. “CCBS not accepted” - Short/long term denial. “B free for A” - No information. Cancel from B” - No information. TERMINAL TO NETWORK “CCBS request” - Complete address to A (one specific terminal). “Cancel CCBS” - Complete address to A. - Indication of one of the following c
15、ases: Last request. All requests. Specific request, including ISDN number to B + subaddress if any. “Reject CCBS” “Accept CCBS” “Compatible and free” “Compatible and busy” “Interrogate CCBS” - Complete address to A. - Complete address to A. - Subaddress if any. - Subaddress if any. - Subaddress if a
16、ny. - Teleservice. - Bearer service. - Indication of one of the following cases: Last CCBS request. All CCBS requests. Specific CCBS request. - In case of specific request then: ISDN number to B + subaddress if any. “Recall” “Status request” “Response to interrogation” NETWORK TO TERMINAL “Notify” -
17、 Subaddress if any. - Teleservice. - Bearer service. - Indication of one of the following cases: CCBS not accepted, short/long term (to A). CCBS accepted (to A). CCBS cancelled (to A). B free (to A). B busy (to A). Monitoring started (to B). CCBS call expected (to B). - In cases “CCBS cancelled” and
18、 “B free”, ISDN number to B. - Subaddress if any. - Teleservice. - Bearer service. - ISDN number to B. - Complete address. - Teleservice. - Bearer service. - CCBS active/not active. - If any CCBS active then ISDN number (+ subaddress if any) to which CCBS is active. In case of all then a list of ISD
19、N numbers. Edition of October 3 1, 1989 - I 2326434 0007885 3 -1 FEI TEA TEA TEA TEA T/S 22-08 E Page 7 FE2 FE3 FE4 KEY: LEA LEB TEB TE: TermhalEquipment LEA NT2 TEB LE: LocalExchange NT2 LEB TEB NT2: ISPBX NT2 NT2 TEB 5. 5.1. 5.2. 5.3. 6. 6.1. 6.2. 6.3. 6.4. 7. 8. SDL-DIAGRAMS FOR FUNCTIONAL ENTITI
20、ES CaU handling, contained in Annex 1. Interrogation, contained in Annex 2. Procedure “Status Request”, contained in Annex 3. FUNCTIONAL ENTITY ACTIONS Functional Entity Actions for FE1 Forward requests from service user to service control entity. Receive and respond to requests and indications rela
21、ting to the service from the service control entity FE2. Functional Entity Actions for FE2 Store call information and users service allocation and state. Verify users service allocation and state. Forward requests and receive indications from Terminating Control Entity FE3 for control of its service
22、. Insert additional information, unique to this service, into basic call requests. Monitor state of originating user. Functional Entity Actions for FE3 Receive and respond to control requests from Originating Control Entity FE2. Store address information and monitor state and service compatibility o
23、f Terminating User. Stimulate call Set-up when terminating party becomes available (for path reservation). Run periodic timers to control monitoring and to terminate service use. Functional Entity Actions for FE4 Receive and respond to requests and indications from Terminating Service Control Entity
24、 FE3 relating to the service. NETWORK PHYSICAL LOCATIONS SCENARIOS The allocation of functional entities to physical locations is shown below: Network Scenario 1. 2. 3. 4. In this Recommendation it is assumed that FE1 and FE4 will always be adjacent to a CCA entity;-i.e. the interface between FE1 an
25、d FE2 and between FE3 and FE4 will be an S or S/T-interface. INTERACTIONS WH OTHER SUPPLEMENTARY SERVICES For further study. Edition of Qctober 31, 1989 ,- licI 23261i11i 0007886 3 TIS 22-08 E Page 8 Annex 1 CALL HANDLING Originating functional entity, FE2 idle (7 basic call * v- rl Start T1 await c
26、all data ( CCBS request )- held in store / discon- nect CCBS T1 request CCBS idle rl - u ! P9 note Edition of October 31, 1989- E 232b414 0007887 5 W accepted TIS 22-08 E Page 9 Annex 1. FE2 request CCBS r2 Start T2 I I 1 F TIS 22-08 E Page 16 Annex 1. FE2 Status request I else R free and compat r2
27、- resume CCBS o pending Edition of October 31, 1989 2326434 0007895 4 i! TIS 22-08 E Page 17 Annex 1. FE2 CCBS request p9 0 -B free at ri - - (-1 recall I start T4 recall 1 set up basic call I) 1 (-) basic cont r oll - call Edition of October 31. 1989 / - 232b43q 0007896 b TIS 22-08 E Page 18 Annex
28、1. Terminating functional entity, FE3 idle (7 request r2 CCBS 1 r2 - no compatible compatible compatible term i na1 and free and busy this B free for Fi Page r2- CCBS idle Edition of October 31. 1 989 7- Edition of October 31, 1989 - TIS 22-08 E Page 19 Annexl. FE3 11 pi8 P insert request 1 in Q to
29、8 accepted -Q -;- notify: ri optional 0 pend i ng Y j TIC 22-08 E Page 20 cance 1 from A T8 2326414 0007898 T E cance 1 other CCBS servi ce Annex 1. FE3 cance t from B r2- Dend i ng (7 cance 1 from B r2- Edition of October 3 I. 1989 -. 2326414 0007899 1 TIS 22-08 E Page 21 Annex 1. FE3 status reques
30、t no compatible .erm i na 1 ompatible and busy compatible and free , blocked I Pote 14 p23 cance 1 from B idle ( pend i ng ) block B for t incoming calls block B for incoming note 3 calls except CCBS call start T7 de 1 ay Edition of October 31, 1989 -. , T . -. Bsl 2326434 0087900 4 B TIS 22-08 E Pa
31、ge 22 Annex 1. FE3 de 1 ay 0 II r2- cance 1 other unblock treat next A in Q to B if any unblock TI (-) P23 Edition of October 31, 19- II 232bLi14 0007901 b E TIS 22-08 E Page 23 Annex 1. FE3 13 p22 P status ompatible and busy unb 1 ock B start T8 from B CCBS idle recal 1 0 Edition of October 31, 198
32、9 ? II 2326434 0007902 A TIS 22-08 E Page 24 Annex 1. FE3 recal 1 i set-u r2 (+$ success- set-u await A-answer attempt Ir: (17 recal 1 U I - rl idle (7 treat next Fi in Q to B if any I Utf blocked I e Edition of October 31, 1989- m 2326434 0007903 T mI TIS 22-08 E Page 25 Annex 1. FE3 await R - answ
33、er rzrl cance 1 from R a Edition of October 31, 1989 1 idle treat next R in Q to 8 if any attempt 1l (R-answer j b 1 ocked re 1 ease call if no 8-channel free, else offer call -rl Pf blocked bas i c idle I 2326414 0007904 1 I CCBS TIS 22-08 E Page 26 Annex 1. FE3 suspended (7 t- cance 1 from B (,) i
34、dle r2 T 12 p21 cance 1 other servi ce Edition October = 232b434 0007905 3 = TIS 22-08 E Page 27 Annex 1 TIMERS IN FE2 TI T2 Retention timer. Max time for user A to request CCBS after A has received B busy indication. Supervision of response to “request CCBS” sent from FE2 to FE3. T2 will expire if
35、signalling is not possible, at signalling failures, or if the TFE cannot response. Duration = a few seconds. CCBS service timer. When T3 expires the CCBS request will be cancelled. The duration of T3 is optional, typically 15-45 minutes. CCBS recall timer. Max time. for user A to respond to a CCBS r
36、ecall. Duration = 20 seconds. CCBS service timer. Normally T6 should havelonger duration than T3, Le. T6 should expire only at emergency. However, at CCBS between different Administrations T6 may have a shorter duration than T3. When T6 expires the CCBS request is cancelled in FE2 as well as in FE3.
37、 Destination B idle guard timer. In case B is blocked for incoming calls, recall is delayed by duration of T7, after B has become free. Duration of T7= 5-10 seconds. The aim of T7 is to ailow B to make a call without being disturbed by CCBS. Recall timer. Normally the duration of T8 should be equal
38、to T4 plus some seconds for CCBS call Set-up and signalling, i.e. T8 should expire at emergency only. T3 T4 TIMERS IN FE3 T6 T7 T8 NOTES GENERAL When entering the state “CCBS idle” all timers are stopped 1. The CCBS call is set up before recall is sent to A. So, recall is sent only if the call is su
39、ccessful. During the call set-up A may be blocked, in order to avoid A being busy before recall is sent. 2. In the diagram sending of “B free for A” is not delayed in the case where B is not blocked. However, such a delay may be implemented without any impact on interactions, 3. Blocking for incomin
40、g calls, implies: - blocking of one B-channel for incoming calls. - blocking of incoming calls using the teleservice requested by CCBS. Rejected incoming calls are given busy-indication. 4. In the case where FE2 has implemented the option of deferring CCBS at A busy, this mechanism may be used also
41、at network congestion. In case of congestion “Resume CCBS” should be delayed in order to avoid a new set-up immediately. Such method does not impact the interworking with FE1 and FE3. ._ Edition of October 3 I, 1989 I r - TIS 22-08 E Page 28 Annex 2 INTERROGATION Outgoing functional entity, FE2 inte
42、rrogote CCBS 1 check response interrogation Edition of October 31, 1989r- - I H 2326434 0007907 7 HI TIS 22-08 E Page 29 Annex 3 PROCEDURE “STATUS REQUEST” Status request I Start 9 delay - sufficient for receiving response from all compatible terminals - Edition of October 31, 1989 r- Compat. “r“ mark : wait for Compat i- r1 Stop T9 result= no compat. terminal I I
