1、I O i 3 CEPT T/CS*qq-b*E = 232b414 0004923 I a Page 1 69 TKS49-06 E Recommendation T/CS 49-06 (Vienna 1982, revised in Montpellier 1984) SYSTEM L1 MULTIFREQUENCY PUSH-BUTTON BIDIRECTIONAL CALL CONTROL SIGNALLING PROCEDURES Recommendation proposed by Working Group T/WG 11 “Switching and Signalling” (
2、CS) Revised text of the Recommendation adopted by the “Telecommunications” Commission: “The European Conference of Postal and Telecommunications Administrations, considering - that multifrequency push-button (MFPB) subscribers line signalling may provide faster call Set-up than decadic - that equipm
3、ent located at subscribers premises and used in private networks employs MFPB signalling techniques - that MFPB interregister signals, as specified in Recommendation T/CS 49-04 i, may be used either in the forward pulsing signalling, more and more, direction only or in both the forward and the backw
4、ard direction, recommends to the members that the call control signalling procedures specified below are used when MFPB interregister signalling is applied in both the forward and backward direction (bidirectional) between private automatic branch exchanges (PABXs) in different countries.” 1. GENERA
5、L 1.1. Field of application In System L1 MFPB bidirectional call control signalling procedures, MFPB interregister signals are used in the forward and backward direction of call Set-up. The MFPB character set of the 16-button array, according to Recommendation T/CS 46-02 2, is applied for address si
6、gnalling and service control. The signalling procedures specified in this Recommendation cover the interchange of additional information possible as compared with System L1 MFPB unidirectional signalling. Interworking with System L1 MFPB unidirectional is inherent in system L1 MFPB bidirectional, pr
7、oviding that System L 1 MFPB unidirectional user appropriate options. 1.2. Signals On international leased lines, System L1 MFPB bidirectional in accordance with Recommendation T/CS 49-04 i is used in conjunction with System L1 line signalling as specified in Recommendation T/CS 49-01 3. The signals
8、 actually used with System L1 MFPB bidirectional call control procedures, contained in this Recommendation, are given in Table 1 (T/CS 49-06). The meanings of the signals comply with Recommendation T/CS 41-01 4. The requirements for the transmission of the signals are set-out in Recommendation T/CS
9、49-01 3, T/CS 49-02 5 and T/CS 49-04 i. Edition of September 15, 1986 CEPT T/CS*49-0b*E 2326434 0004924 3 TICS 49-06 E Page 2 2. 2.1. 2.1.2. 2.2. 2.3. Signals Seizing Proceed-to-send Address Clear-request Address-complete Answer Clear-forward Clear-back Cleared Busy-extension-changed-to-free Forward
10、-service-request-recall Forward-link-recall Backward-service-request-recall Backward-link-recall Proceed-to-send-on-recall Type-of-call Class-of-service Calling-line-identity End-of-block Call-refusal Called-line-identity State-of-destination Recommendation T/CS 49-01 T/CS 49-02 T/CS 49-04 T/CS 49-0
11、1 T/CS 49-02 T/CS 49-01 T/CS 49-01 T/CS 49-01 T/CS 49-01 see Section 2.6. T/CS 49-01 T/CS 49-01 T/CS 49-01 T/CS 49-01 TICS 49-02 and TICS 49-04 T/CS 49-04 T/CS 49-04 TICS 49-04 TICS 49-04 T/CS 49-04 TICS 49-04 TICS 49-04 Table 1 (T/CS 49-06). Signals used in system L1 MFPB bidirectional call control
12、 signalling procedures. SIGNALLING PROCEDURES General The description of the call and service control signalling procedures are described by means of SDL diagrams, in accordance with CCITT Recommendations Z. 101 6, Z. 102 7 and Z. 104 8, and narrative comments. Table 4 in Recommendation T/CS 49-04 i
13、ncludes abbreviations used in System LI MFPB SDL diagrams. Nole: The SDL diagrams are included in this Recommendation to assist in the understanding of the technical text, and must only be used in association with the text. In System L1 MFPB bidirectional, the use of backward MFPB signals begins wit
14、h the dialogue phase. In multi-link connections, the address-complete signal will cause the registers of the transit switches to release and switch through the speech paths, preparing for the subsequent end-to-end transmission of MFPB codes in both directions. The registers of the originating and th
15、e terminating PABXs will not yet be released. When a service demand requires inter-PABX MFPB signalling, the request is handled by the responding PABX on an accept or reject basis, depending upon the availability of the service at that PABX. Duplex and semi-duplex transmission mode If (national) two
16、-wire links are included in a given inter-PABX network, the interchange of the dialogue phase signals will be in either a duplex or a semi-duplex transmission mode. This requires mutual agreement by the parties involved (the line signalling for two-wire links is not covered by System L1 Recommenda-
17、tions). In the duplex mode, the outgoing PABX will continue sending dialogue phase forward signals, without awaiting the backward end-of-block signal. In the semi-duplex mode, the outgoing PABX refrains from sending en-bloc dialogue phase forward signals until the outgoing PABX has indicated the end
18、 of the dialogue phase backward en-bloc signal sequence by the transmission of the end-of-block signal. Separate SDL diagrams are included for semi-duplex mode (see Section 2.4.). Signalling compatibility check By means of the signalling compatibility check (see Recommendation T/CS 49-04 i) the outg
19、oing PABX determines whether the incoming PABX is capable of System L1 MFPB bidirectional, or only System L1 MFPB unidirectional signalling. If the outgoing PABX receives MFPB dialogue phase backward signals, the result of the signalling compatibility check is positive. Edition of September 15, 1986
20、 CEPT T/CS*Liq-Ob*E E 232bYLY OOOLi725 5 M 2.4. 2.5. O 2.6. 2.7. 2.8. 2.9. TICS 49-06 E Page 3 If the incoming PABX is not capable of System L1 MFPB bidirectional signalling, it would have already released the register and not reacted to the dialogue phase forward signals. This state is shown on the
21、 SDL diagrams as the post-dialling state. If the outgoing PABX does not recognise a first dialogue phase backward signal in accordance with Recommendation T/CS 49-04 i, it changes to its post-dialling state, too. Interchange of additional information (dialogue phase) Figures 1 (T/CS 49-06) and 2 (T/
22、CS 49-06) show the signalling sequence at the outgoing and incoming PABXs line interfaces for the duplex mode of signal transmission. Figures 9 (T/CS 49-06) and 10 (T/CS 49-06) refer to the semi-duplex mode. The four state transition diagrams start with the end of selection state and include the sig
23、nalling compatibility check. The additional information interchange shall be based on the dialogue phase signals specified in Recom- mendation T/CS 49-04 i. Upon recognition of the end of the dialogue phase (i.e. upon transmission of the relevant forward and backward end-of-block signals), the origi
24、nating and terminating PABXs shall release their registers, and change to the state referred to as post-dialling state in the SDL diagrams. Register-recall Figures 5 (T/CS 49-06) to 8 (T/CS 49-06) show the register-recall procedures at the PABX line interfaces. The form of proceed-to-send-on-recall
25、signal (2,280 Hz signal or MFPB signal) indicates that the responding transit switch is capable of System L1 MFPB unidirectional or bidirectional interregister signalling. In System L1 MFPB bidirectional working, the initiating PABX will continue with the signalling compatibility check. Intrusion Th
26、e called-party-changed-to-free signal in the intrusion procedure after call set-up requires the use of the backward-service-request-recall signal. Upon recognition of the MFPB proceed-to-send-on-recall signal sent in response, the called-party-changed-to-free signal, coded as the character Ir, is tr
27、ansmitted backwards, Figures 3 (TCSI 49-06) and 4 (T/CS 49-06) refer. Clear-request on non-receipt of address information After recognition of a seizing signal, if no address information or incomplete address information is received, the incoming PABX shall time-out and dissociate the inter-PABX cir
28、cuit from any common equipment. Under these conditions, the incoming PABX shall: (a) apply the clear-request signal; (b) bar access to the inter-PABX circuit for outgoing calls until a clear-forward signal is recognised. Clear-request on encountering congestion or an engaged extension Due to supplem
29、entary services providing the possibility of changing from an unsuccessful to a successful call situation, this procedure is not foreseen with System L1 MFPB interregister signalling. It may, however, still occur when the incoming PABX has indicated that it is capable of System L1 MFPB unidirectiona
30、l signalling only, and executes the procedure specified in Recommendation T/CS 49-05 9. The outgoing PABX has to comply with that procedure after the signalling compatibility check. Audible indications Provisions must be made by the parties involved to ensure that the correct audible indications are
31、 returned to the caller when Sections 2.7. or 2.8. above apply. REFERENCES Recommendation T/CS 49-04. System LI mult$requency push-button interregister signalling. Recommendation T/CS 46-02. Multifrequency signalling system to be used for push-button telephones. Recommendation TICS 49-0 I. System L1
32、 line signalling over international inter-private automatic branch ex- change lines. Recommendation T/CS 41 -01, Signal and signalling message names und meanings. Recommendation T/CS 49-02. System LI decadic pulsing interregister signalling. CCITT Recommendation Z. 101. General explanation of the sp
33、ecification and description language (SDL). CCITT Recommendation Z. 102. Symbols and rules. CCITT Recommendation Z. 104. Semantics. Recommendation TICS 49-05. System LI MFPB unidirectional signalling procedures. Edition of September 15, 1986 CEPT T/CS*49-0b*E W 2326414 O004926 7 = TICS 49-06 E Page
34、5 SDL CHARTS uid of select Im WtgOlrig OUplRx Dode 1 Awltlq order to d 1st fpusd DPS 1 For the call set-up preceding the procedures shown, Recommendation T/CS 49-05 5 applies. Note: The connector and state indications refer to the signalling sequence SDL charts of Recommendation T/CS 49-05. I Awltlq
35、 1st JL I I I I I I fwl. called IlIn? Identltil. 1% Interrqllster Hote Thp alsuer Slgd ad thp bldlmtlmlnot-psslble Indlcatlm mly am- uhpn Intmwrklq VI th system L1 17pB uildlrect Imi. - Q F fonisd me (-1 Interrqllster (7) (*) Figure 1. (T/CS 49-06). Signalling compatibility check and duplex intercha
36、nge of dialogue phase signals (outgoing PABX). Edition of September 15, 1986 CEPT T/CS*49-0b*E TtCS 49-06 E Page 6 sulcct lm -=il spv I ce- Predlalliq fanad servlce- rep Intercqlister F“I on recall (+-J LzLzJ Avaltlng arder mb recal I Il* recall Pre-dialling Irk recall 6 on recall Figure 8 (T/CS 49-
37、06). Backward register-recall (incoming PABX). Edition of September 15, 1986 TICS 49-06 E Page 10 -, CEPT T/CS*49-0b*E 0 2326434 0004933 O Awaiting Ist o Bldirectlanal pmslble I Reascn far re- -17 fusal. called iim idmtittj. intemglster (7) Hote The alsver sigial ad the - bldlrect lonalnot-passlble
38、Indlcatlm miy DCCW uhen intlng VI th sipta L1 PFPB viidlrectlmal. Q I Idle Figure 9 (T/CS 49-06). Signalling compatibility check procedure and semi-suplex interchange of dialogue phase signals (outgoing PABX). Edition of September 15, 1986 CEPT T/CS*49-0b*E m 232b4L4 0004932 2 m ClaS- forwsd TICS 49-06 E Page 11 Clear- =w=t select lai Incmlq - fa- refusal - After cles-daun at InCrilng PPX refusal.calld (El Ilne Identltq o (z-) Postdialilq
