Recommendation T/CS (Vienna 1982, revised in Montpelier 1984)

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1 o B T/CS Page Recommendation T/CS (Vienna 982, revised in ontpelier 984) SYSTE L ULTFREQUENCY PUSH-BUTTON UNDRECTONAL CALL CONTROL SGNALNG PROCEDURES Recommendation proposed by Working Group T/WG Switching and Signaling (CS) Revised tet of the Recommendation adopted by the Telecommunications Commission: The European Conference of Postal and Telecommunications Administrations, considering that multifrequency push-button (FPB) subscribers line signaling may provide faster call set-up than decadic pulsing signaling, n that equipment located at subscribers premises and used in private networks more and more employs FPB signaling techniques, that FPB interregister signals as specified in Recommendation T/CS [] may be used either in the forward direction only or in both the forward and the backward direction, recommends to the members that the call control signaling procedures specified below are used, when FPB interregister signaling is applied in the forward direction only (unidirectional) between private automatic branch echanges (PABXS), in different countries.. GENERAL.. Field of application.2. Signals n the System L FPB unidirectional call control signaling procedures, FPB interregister signals are only used in the forward direction of call set-up, e.g. the FPB character set of the 2-button array according to Recommendation T/CS [2] is used for address signaling and service control. The signaling procedures specified in this Recommendation cover the standard call set-up and call clear-down. Enhancements providing the interchange of additional information are given as options, e.g. for recall and intrusion. On international leased lines, System L FPB unidirectional, in accordance with Recommendation T/CS [], is used in conjunction with System L line signaling as specified in Recommendation T/CS 49-0 [3]. The signals actually used with System L FPB call control procedures contained in this Recommendation are given in Table (T/CS 49-05). The meanings of the signals comply with Recommendation T/CS 4-0 [4]. The requirements for the transmission of the signals are set-out in Recommendations T/CS 49-0 [3], [5] and T/CS []. The use of the address-complete signal and the answer signal is subject to options 2 and 3, respectively. The three signals, address-complete, etension-free; address-complete, etension-busy and busy-etensionchanged-to-free, may be chosen instead of the address-complete signal (option 4). f the signals intrusion and end-of-intrusion are used (option 5), then option 3 must be applied. The four recall signals represent option 6. All options must be mutually agreed upon by the parties involved. Option provides for the use of the seizing-acknowledgement signal instead of the proceed-to-send signal.

2 TJCS Page 2 Signals Seizing Proceed-to-send Seizing-acknowledgement Address Clear-request Address-complete Answer Clear-forward Clear-back Cleared Address-complete, Address-complete, etension-free etension-busy Busy-etension-changed-to-free ntrusion End-of-intrusion Forward-service-request-recall Backward-service-request-recall Backward-link-recall Proceed-to-send-on-recall Reconnect Option Recommendation T/CS 49-0 T/CS 49-0 T/CS T/CS 49-0 T/CS 49-0 T/CS 49-0 T/CS 49-0 T/CS 49-0 T/CS 49-0 T/CS 49-0 T/CS 49-0 T/CS 49-0 T/CS 49-0 Legend:, 2, 3, 4, 5, 6: option, 2, 3, 4, 5, 6. : andatory. Table (T/CS 49-05). Signals used in System L FPB unidirectional call control signaling. Note : f option is provided, the seizing-acknowledgement procedure must be used instead of the proceed-to-send procedure. 2. SGNALNG PROCEDURES 2.. General 2... The signalling procedures are described by means of SDL diagrams in accordance with CCTT Recommendations Z.0 [7], Z. 02 [8] and Z. 04 [9], and narrative comments. Table 4 in Recommendation T/CS [] includes abbreviations used in the SDL diagrams. Note: The SDL diagrams are included in this Recommendation to assist in the understanding of the technical tet and must only be used in association with the tet. Where a service demand requires inter-pabx FPB signaling, the request is handled by the responding PABX on an accept or reject basis, depending upon the availability of the service at that PABX Set-np and clear-down of standard calls Figures, 2 and 9 (T/CS 49-05) show the signaling sequences at the outgoing and incoming PABX line interfaces for set-up and clear-down of standard calls. Following the proceed-to-send signal, the register of the outgoing PABX sends the address signals. n the case of multi-link calls, the address signals are transferred link-by-link. The registers in the transit switches should preferably work in an overlap mode of operation. The selection phase is concluded by the address-complete signal sent backwards from the destination PABX by address information analysis or internal time-out. The address-complete signal releases the registers in the terminating PABX and transit switches, initiates through-connection of the speech path and causes the transition to the end-of-selection state at the reference interfaces. n the end-of-selection state an additional signal interchange (e.g. covering options 3 or 3 and 4) may take place and cause transition to another state. For the SDL diagrams, this state is called post-dialling state Register-recall When option 5, register-recall, is provided, Figures 3 to 6 (T/CS 49-05) apply. n the case of a service-request recall, no address-complete signal will be returned. Subsequently, the signaling process reverts to the appropriate post-dialling state ntrusion The procedure for intrusion requires the provision of options 3 and 4. Figures 7 and 8 (T/CS 49-05) apply.

3 T/CS Page 3 SQzlrg bb Awaiting Selzlng adglg4gd@tmt u Aualti~ C Dclearfcward 7cleared + Aualtlq WC& to smd dlglts )Q dle %-d No Ulth dlglts qdlm 3 cptlm 3 i Aualtlq addltlrma[ kkward nfo. F97 (T/tSW-OS) A Reka.?.e cd [ C3 Ed of sel=tim Wtgo l-g = faofu-tf-w nterreglskr slg?ellir&3 (Z3 Pmtdlalllng Wtgcllng (5 B a fielaesa m% Figure (T/CS 49-05). Call set-up (outgoing PABX). c)dle

4 T/CS Page 4 zdle Seizing With opton After clear-downat ncornlng PABX No Opton3 btect address. complete With 0pt0n3 F98 (T/CS$9-05 Y Q Dlglts daddress cmp(ete Reease Cal of selecton r)end incomng c Release Figure 2 (T/CS 49-05). Call set-up (incoming PABX). u

5 T/CS Page 5 /--- n Post-dla[llng ( outgoing ) 42, k< forward sew cereq..recal AnSver \ / \ asend forward servce. req.-recal (5 asend forward inkrecal n bl&kwrd sew cereq.-orlink recal[ Q%lzedby backwardlink or sgrvlcere -reca[[ DForward S a-vcereq..reca{ QPre-dla((ng al s a-vlmmq..reca &Procwd to smd on mcell (5 DFomwd lnkrecall TPre-dia[ng on [rkrecakt Proceed to send on recall nreconmct 6 mawl;;~gm~der m-v CQ-req- nfo.dl ts al Send digits Digits (!) Send digits Dlglts 8 YEnd of sew cereq -info. detected Address coli@ete Post-dialng outgoing -9 DceeJ-- forwrd Cleared c(ear-d.wnat 4 Figure 3(T/CS 49-05). Forward register-recall (outgoing PABX).

6 T/CS Page 6 ( Post-diallng mom ng ) 0W2edzec: req.-rem aforward s$i-vcqreq.-recd Fcrvard say-vlmrec.-recal[ S+3 Sackwrd Forwrd Baci(vard Servlc& nk-recal nk-recal raq.-reca(( i Seizedby Pre-dialng forwardtlnk- Pre-dla(ng on servlce- On swvlcereq m * r~a[[ req.-r~a( -reca[[ to smd reca[ +(:Proc@d Avalting nfa.m reca~[ Recornwct c) Y JDlglts End of C#:; 5ervlcadetected rq. -lnf0. &tected Q Y uralease cd ( Post-dialng rmndng dle Figure 4 (T/CS 49-05). Forward register-recall (incoming PABX).

7 T/CS Page i Post-dla[ng Outgoing % CK AnSwr Backward saw cereq-recal Backward [nk-recal Seizedby backwardl*- or su-vlcereq -meal Swd forvard Swv cerecal Forward sew ca- req -reca[\ Pre-dlatllng m servlc- re$ -reca([ ESend forvard (nk meal [ Foward [nk-recal P=dla((lng [irkrecall,< (,:8 (!) LEDD A TUaltlngfor backwrd m-v Ce-req- nfo. Dlglts () End &Complete War& address ra detected da 5+ Add$ess cmrplete Post-dialllng ncomlng QRelease 8 cl Ckwed Cleared!3Aftm are(ease cal &clearbac cearfomwd Release clear-downat outgoing PABX Figure 5 (T/CS 49-05). Backward register-recall (outgoing PABX). ld(e

8 T/CS Page 8 &Post-dlalllng rmmlng Y &?i%-i asarsl (5 Y 0SOd,ypr-d rsca[l AForuW so-vlcsraq.-mcfdl klevard ssl-vlcera$-rscdll asswlcqreq.+-acall (3(. ) Pgf&m z= rsmmct 23 Pr+aad to send on rseall Auay;mddw Salzsdty fcmm-d sgi-vlcemq,-mcall s9-vlca- -meal ssrvice- -nfo. oy TEd of sswlcem$l.-l; QDlglts &Y Sdsase Ca[( ~w Poatdlalllng wtgolng 8el aa= Q 8sleaaQ Figure 6 (T/CS 49-05). Backward register-recall (incoming PABX). \ J

9 -r/es Page 9 Addrass Colplete of Selecton (3End!2 E; ( Postdla[llng Wtgolrg UlswcessfU ) asmfm C3 ntrusion msad SllcLOf - intruslm DEnd-ofintrusion = CJ Postdlalllng Wtgulrg m Q G) o@lease selease CL* 4 Aftw C aar-cbvnat Wtgolrg PASX Figure 7 (T/CS 49-05). Options 4 and 5 (outgoing PABX).

10 -rjcs Page 0 m:; % ) zsodbusy detected soobusy (=2 Post-dialng ncomlng Unsuccessfu( aaddress ccirplete Soo (=3 End of select[m abusy.changedtc-free sodfree d+kcted < csoofl-w X ntruslm [ ntwslon ) \ J aend-of- ntruslm cl Bus+changedto-free C-3 Post-dial[ng ncornng Y r?< ReLease ca( nrelease D Release After C(m--tin at Figure 8 (T/CS 49-05). Options 4 and 5 (incoming PABX). Edition of Septe~ber 5, 986

11 TCS Page After Cleared Cleared - ~~t~~~~wn at }{ PABX -i ear- :(=l=l :ed DLE ~ Outgoing PABX ncoming PABX Figure 9 (T/CS 49-05). Call clear-down Clear-request on non-receipt of address information When after recognition of a seizing signal, no address or incomplete address or incomplete information is received, the incoming PABX shall time-out and dissociate the inter-pabx circuit 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 recognized. Clear-request on encountering congestion or an engaged etension This procedure is optional. When an incoming PABX encounters congestion or an engaged etension, it may release the switching equipment, apply the clear-request signal and perform the procedures specified in $2.5. (b). Andible indications Provision must be made by the parties involved to ensure that the correct tones are returned to the caller when Sections 2.5. or 2.6. above apply. [] [2] [3] P [4] [5] [6] [7] [8] [9] REFERENCES Recommendation T/CS System L multfrequency push-button interregister signaling. Recommendation T/CS ultl~requency signaling system to be used for push-button telephones. Recommendation T/CS System L line signaling over international inter-private automatic branch echange lines. Recommendation T/CS 4-0. Signal and signaling message names and meanings. Recommendation TCS System L decadic pulsing interregister signaling. Recommendation T/CS System L decadic pulsing signaling procedures. CCTT Recommendation Z. 0. General eplanation of the specification and description language (SDL). CCTT Recommendation Z. 02. Symbols and rules. CCTT Recommendation Z. 04. Semantics.

Recommendation T/CS (Vienna 1982, revised in Montpelier 1984) SYSTEM L1 MULTIFREQUENCY PUSH-BUTTON INTERREGISTER SIGNALING

Recommendation T/CS (Vienna 1982, revised in Montpelier 1984) SYSTEM L1 MULTIFREQUENCY PUSH-BUTTON INTERREGISTER SIGNALING o -r/es 49-04 E B Page 1 Recommendation T/CS 49-04 (Vienna 1982, revised in Montpelier 1984) SYSTEM L1 MULTFREQUENCY PUSH-BUTTON NTERREGSTER SGNALNG Recommendation proposed by Working Group T/WG 11 Switching