1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T Q.140-Q.180TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (11/1988) SERIES Q: SWITCHING AND SIGNALLING Specifications of Signalling System No. 5 ITU-T Recommendations Q.140-Q.180 (Formerly CCITT Recommendations) ITU-T Q-SERIES RECOMMENDATIONS SWITCHING A
2、ND SIGNALLING SIGNALLING IN THE INTERNATIONAL MANUAL SERVICE Q.1Q.3 INTERNATIONAL AUTOMATIC AND SEMI-AUTOMATIC WORKING Q.4Q.59 FUNCTIONS AND INFORMATION FLOWS FOR SERVICES IN THE ISDN Q.60Q.99 CLAUSES APPLICABLE TO ITU-T STANDARD SYSTEMS Q.100Q.119 SPECIFICATIONS OF SIGNALLING SYSTEM No. 4 Q.120Q.13
3、9 SPECIFICATIONS OF SIGNALLING SYSTEM No. 5 Q.140Q.199 SPECIFICATIONS OF SIGNALLING SYSTEM No. 6 Q.250Q.309 SPECIFICATIONS OF SIGNALLING SYSTEM R1 Q.310Q.399 SPECIFICATIONS OF SIGNALLING SYSTEM R2 Q.400Q.499 DIGITAL EXCHANGES Q.500Q.599 INTERWORKING OF SIGNALLING SYSTEMS Q.600Q.699 SPECIFICATIONS OF
4、 SIGNALLING SYSTEM No. 7 Q.700Q.799 Q3 INTERFACE Q.800Q.849 DIGITAL SUBSCRIBER SIGNALLING SYSTEM No. 1 Q.850Q.999 PUBLIC LAND MOBILE NETWORK Q.1000Q.1099 INTERWORKING WITH SATELLITE MOBILE SYSTEMS Q.1100Q.1199 INTELLIGENT NETWORK Q.1200Q.1699 SIGNALLING REQUIREMENTS AND PROTOCOLS FOR IMT-2000 Q.1700
5、Q.1799 SPECIFICATIONS OF SIGNALLING RELATED TO BEARER INDEPENDENT CALL CONTROL (BICC) Q.1900Q.1999 BROADBAND ISDN Q.2000Q.2999 For further details, please refer to the list of ITU-T Recommendations. Signalling System N 5 (1988) i ITU-T Recommendations Q.140-Q.180 Specifications of Signalling System
6、No. 5 Source ITU-T Recommendations Q.140-Q.180 were prepared by CCITT Study Group XI (1985-1988) and approved by WTSC in Melbourne on 25 November 1988. Those texts include the amendments to ITU-T Recs. Q.141 and Q.144 by WTSC on 12 March 1993. Those texts were originally published in Blue Book, Fasc
7、icle VI.2. ii Signalling System N 5 (1988) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying tec
8、hnical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T study groups whi
9、ch, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSC Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and
10、 IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommenda
11、tion may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval
12、 of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB pate
13、nt database. ITU 2002 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from ITU. Signalling System N 5 (1988) iii CONTENTS Specifications of Signal
14、ling System No. 5 Rec. No. Page Q.140 Definition and function of signals 3 Q.141 Signal code for line signalling 6 Q.142 Double seizing with both-way operation 11 Q.143 Line signal sender 12 Q.144 Line signal receiver 13 Q.145 Splitting arrangements . 15 Q.146 Speed of switching in international exc
15、hanges 16 Q.151 Signal code for register signalling 17 Q.152 End-of-Pulsing conditions Register arrangements concerning ST (end-of-pulsing) signal 18 Q.153 Multifrequency signal sender. 19 Q.154 Multifrequency signal receiver. 20 Q.155 Analysis of digital information for routing 21 Q.156 Release of
16、international registers . 21 Q.157 Switching to the speech position 22 Q.161 General arrangements for manual testing. 23 Q.162 Routine testing of equipment (local maintenance). 23 Q.163 Manual testing 24 Q.164 Testing equipment for checking equipment and signals 27 Q.180 Interworking of systems No.
17、4 and No. 5 . 43 Signalling System N 5 (1988) 1 SPECIFICATIONS OF SIGNALLING SYSTEM No. 5 INTRODUCTION PRINCIPLES OF No. 5 SIGNALLING SYSTEM General System No. 5 is compatible with both TASI1)and non-TASI-equipped circuits and may be applied for automatic and semi-automatic operation and both-way wo
18、rking. It requires four-wire signalling and automatic access to the outgoing circuits. The signalling equipment is in two parts: a) line signalling for the so-called supervisory signals; and b) register signalling for the numerical signals. a) Line signalling This is a link-by-link system using two
19、in-band signalling frequencies 2400 Hz and 2600 Hz, two frequencies, instead of one frequency, being adopted for the following reasons: i) Automatic detection of double seizing on both-way working; ii) Frequency discrimination between signals, no time discrimination being incorporated. Automatic det
20、ection of double seizing requires that the frequency of the proceed-to-send signal (2600 Hz) be different from that of the seizing signal (2400 Hz). The detection is achieved when one end transmits the outgoing seizing signal (2400 Hz) and at the same time receives the seizing signal (2400 Hz) from
21、the other end and not the 2600 Hz proceed-to-send signal expected. All signal recognition times are the same (125 ms) except for the seizing and proceed-to-send signals (40 ms). These two signals are not subject to signal imitation by speech and fast signalling is desired in particular to minimize d
22、ouble seizings. To avoid, with this signalling system, relatively slow signalling in non-TASI applications and in lightly loaded conditions (the more usual) of TASI applications, all signals are the continuous compelled2)type except the forward transfer signal. Continuous signals ensure TASI trunk/c
23、hannel association during the actual time this function requires. (The alternative of TASI-prefix pulse type signals would, due to the 500-ms TASI prefix, introduce a slight risk of failure to associate a trunk with a channel, and would slow the signalling in terms of restoration of the transmission
24、 path after the signalling line splits under the more usual conditions of TASI loading and in non-TASI applications.) Only the forward-transfer signal is a TASI-prefixed pulse since for this signal a slight risk of failure can be accepted because it is operator-controlled and may be repeated at will
25、. _ 1)See Supplement No. 2 in Orange Book, Volume VI.1 (1976). 2)See for this term Recommendation Q.141, 2.1.6 2 Signalling System N 5 (1988) Except for the answer signal, all the compelled signals are normal compelled3)type. For reasons of fast speed, the answer signal is overlap-compelled4)at tran
26、sit points. Fast answer signalling is desirable to minimize the risk of an abandoned call by either the called or calling party, should the verbal answer be lost due to the line splitting on answer signalling. b) Register signalling This is a link-by-link 2/6 multifrequency (m.f.) in-band en block4)
27、pulse signalling system, forward signalling only. The alternative, continuous compelled signalling, would be slow due to the long circuit propagation times in certain applications. The frequencies (700 Hz . . . 1700 Hz) are outside of the line signalling frequencies. The numerical information signal
28、ling is preceded by a KP signal (start-of-pulsing) and terminated by an ST signal (end-of-pulsing). En bloc non-overlap sending4)applies at the outgoing international register, the seizing signal being sent, and thus the international circuit being taken as late as possible, namely when the ST condi
29、tion is available in the outgoing international register. When sending, the outgoing register pulses out in a continuous sequence. The prior GO trunk/channel association due to the seizing signal is maintained by the TASI speech detector hangover during the interval between cessation of the seizing
30、signal (on receipt of the proceed-to-send signal) and the start of the register pulse out, and during the intervals between successive m.f. signals. En bloc overlap register signalling4)applies at the international transit registers and at the incoming international register to minimize the post-dia
31、lling delay. Compandors affect signalling, particularly short-pulse compound signalling (e.g. register signalling), due to distortion and the production of intermodulation frequencies. By virtue of the lin-by-link signalling and the adopted duration of the m.f. pulses, system No. 5 functions correct
32、ly in the presence of compandors. _ 3)See for these terms Recommendation Q.141, 2.1.7. 4)See for these terms footnote to Recommendation Q.151, 3.1.1 Signalling System N 5 (1988) 3 CHAPTER I DEFINITION AND FUNCTION OF SIGNALS Recommendation Q.140 1. DEFINITION AND FUNCTION OF SIGNALS 1.1 seizing sign
33、al (sent in the forward direction) This signal is transmitted at the beginning of a call to initiate circuit operation at the incoming end of an international circuit and to seize equipment for switching the call either to the national network of the incoming country or to another international exch
34、ange. 1.2 proceed-to-send signal (sent in the backward direction) This signal is sent from the incoming end of an international circuit, following the receipt of a seizing signal, to indicate that the equipment is ready to receive the numerical signals. 1.3 start-of-pulsing signal, also called for s
35、ystem No. 5 “KP signal“ (sent in the forward direction) This numerical type signal is sent on receipt of a proceed-to-send signal and may be used to prepare the incoming international register for the receipt of the subsequent numerical signals. Two different KP signals are provided to discriminate
36、between terminal and transit calls: a) KP1, terminal; and b) KP2, transit. 1.4 numerical signal (sent in the forward direction) This signal provides an element of information necessary to effect the switching of the call in the desired direction. There is always a succession of numerical signals sen
37、t. 1.5 end-of-pulsing signal, also called for system No. 5 “ST signal“ (sent in the forward direction) This numerical type signal is sent to show that there are no more numerical signals to follow. The signal is always sent in semi-automatic as well as in automatic working. 1.6 busy-flash signal (se
38、nt in the backward direction) This signal, which is sent only after the proceed-to-send signal, is sent to the outgoing international exchange to show that either the route, or the called subscriber, is busy. The conditions of use of this signal are as follows: a) An international transit exchange m
39、ust send this signal after register association, to indicate that there is congestion at that exchange or on the appropriate outgoing routes. 4 Signalling System N 5 (1988) b) An incoming international exchange must send this signal, after register association, if there is congestion at that exchang
40、e or on the outgoing routes directly connected to it, but sending the signal is optional when there is congestion beyond that exchange (when there is congestion at a point in the national network of the incoming country or when the called subscribers line is busy). This signal is optional because th
41、ere are several countries that do not send it from their national networks. Note The receipt of the busy-flash signal at the outgoing exchange will cause: an appropriate indication to be given to the outgoing operator or to the calling subscriber; and the sending of the clear-forward by the outgoing
42、 exchange to release the international connection (except when otherwise arranged, for example, in this case of observations on circuits). 1.7 answer signal (sent in the backward direction) This signal is sent to the outgoing international exchange to show that the called party has answered the call
43、1). In semi-automatic working, the signal has a supervisory function. In automatic working, it is used: to start metering the charge to the calling subscriber; to start the measurement of call duration for international accounting purposes. 1.8 clear-back signal (sent in the backward direction) This
44、 signal is sent to the outgoing international exchange to indicate that the called party has cleared. In the semi-automatic service, it performs a supervisory function. It must not permanently open the speech path at the outgoing international exchange. In automatic working, arrangements must be mad
45、e to clear the international connection, stop the charging and stop the measurement of call duration if, between 1 and 2 minutes after receipt of the clear-back signal, the calling subscriber has not cleared. Clearing of the international connection should preferably be controlled from the point whe
46、re the charging of the calling subscriber is carried out. Notes on the answer and clear-back signals. See the corresponding Notes in Recommendation Q.120. 1.9 clear-forward signal (sent in the forward direction) This signal is sent in the forward direction at the end of a call when: a) in semi-autom
47、atic working, the operator at the outgoing international exchange withdraws her plug from the jack, or when an equivalent operation is performed; b) in automatic working, when the calling subscriber hangs up or otherwise clears (as in the case of a subscribers installation with extension telephones)
48、. This signal is also sent after receipt of a busy-flash signal by the outgoing international exchange, and when there is forced release of the connection (see Recommendation Q.118, 4.3.1 and 4.3.2 for automatic working and 4.3.1 for semi-automatic working). This signal may also be sent after an abn
49、ormal release of an outgoing register in the case indicated in Recommendation Q.156 under 3.6.2 a) 1. 1.10 release-guard signal (sent in the backward direction) This signal is sent in the backward direction in response to the clear-forward signal. It serves to protect an international circuit against subsequent seizure as long as the disconnection operations controlled by reception of the clear-forward signal have not been completed at its incoming end. _ 1)See Recommendation Q.27 for
