1、 ITU-T RECMN*U-L 73 4862573 0588733 834 = INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU TELEGRAPH SWITCHING GENERAL u.l (03/93) SIGNALLING CONDITIONS TO BE APPLIED IN THE INTERNATIONAL TELEX SERVICE ITU-T Recommendation U.1 (Previously “CCIlT Recommendat
2、ion”) ITU-T RECMN*U-L 93 48b259L 0588739 770 FOREWORD The Telecommunication Standardization Sector (ITU-T) is a permanent organ of the International Telecom- munication Union. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a v
3、iew to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC). which meets every four years, established the topics for study by the IT-T Study Groups which, in their turn, produce Recommendations on these topics. ITU-T Recommendation U.l
4、 was revised by the ITU-T Study Group IX (1988-1993) and was approved by the WTSC (Helsinki, March 1-12, 1993). NOTES 1 As a consequence of a reform process within the International Telecommunication Union (ITiJ), the CCITT ceased to exist as of 28 February 1993. In its place, the ITU Telecommunicat
5、ion Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector. In order not to delay publication of this Recommendation, no change has been made in the text to references containing the
6、acronyms “CCITT, CCIR or IFRB” or their associated entities such as Plenary Assembly, Secretariat, etc. Future editions of this Recommendation will contain the proper terminology related to the new IT structure. 2 telecommunication administration and a recognized operating agency. In this Recommenda
7、tion, the expression “Administration” is used for conciseness to indicate both a O ITU 1994 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 t
8、he ITU. 1 2 3 4 5 6 7 8 9 10 11 12 13 ITU-T RECMN*U.L 93 m Y862591 0588735 607 m CONTENTS Signalling types Free line condition Call . Cail-confirmation signal . Signals preceding selection 5.2 Proceed-to-transmit signal Selection signals . Call-connected signal . Idle circuit condition Clearing 9.1
9、Clearing signal 9.2 Clear-confirmation signal . 9.3 Guard delay . Service signals 10.1 10.2 Waiting signals . 10.3 Service-connected signal 10.4 Backward busying signal 10.5 Retest signal 5.1 Proceed-to-select signal Signals for ineffective calls . Setting-up time . Both-way working Transit working
10、References . Recommendation U.1 (03/93) Page 1 4 4 4 4 4 5 5 5 6 6 6 6 7 7 7 8 9 9 9 10 10 10 11 ITU-T RECMNUU.3 93 W 4862573 0588736 543 W Recommendation U.1 SIGNALLING CONDITIONS TO BE APPLIED IN THE INTERNATIONAL TELEX SERVICE (Former CClT Recommendation E.l, Arnhem, 1953; amended at Geneva, 1956
11、, New Delhi, 1960, Geneva, 1964, Mar del Plata, 1968, Geneva, 1972,1976, 1980, Malaga-Torremolinos, 1984; Melbourne, 1988 and Helsinki, 1993) The CCIT, considering (a) on international telex circuits in putting through, supervising, clearing, and charging for international telex calls; that signalli
12、ng conditions in the international telex service require accurate definition of the signais to be used (b) that these signais must be such as to take into account that there are some fairly important differences in makeup between the telex networks of different countries. In some countries, selectio
13、n is done by dialling, in others by means of start-stop signais. Some networks use direct selection while others use register translators. Between some networks, subscriber automatic selection is used whilst, in relations with other networks, semi-automatic or manual selection is still being used; (
14、cl that hence it has not been possible to lay down uniform signals for all internationai telex relations. While, for certain signais, it has been possible to lay down rules valid for ail relations, for others the choice has been left between two types of signals known as type A and type B, within ea
15、ch type it has sometimes been necessary to provide alternative forms for certain signais. The signais with regard to which there is a choice are described in Tables la, lb and 2 below; (4 that it is intended that the signalling with which this Recommendation deals should apply as far as possible whe
16、n telex circuits make use of transmission devices having multiplex and signal regeneration facilities. In the case of operation over error-corrected radio circuits, Recommendaton U.20 lays down the conditions for adapting the signalling defined in this Recommendation. In the case of operation over c
17、hannels using synchronous multiplex equipment in accordance with Recommendation R.44, Recommendation U.24 lays down the conditions for adapting the signalling defined in this Recommendarion. When the signais defined in this Recommendation are transmitted via code and speed dependent systems in accor
18、dance with Recommendation R. 101, Recommendation U.25 lays down the permitted variations to the signals defined in this Recommendation. When the signals defined in this Recommendation are transmitted via regenerative repeaters the signals received from these transmission devices may lie outside the
19、tolerances stated in this Recommendation, and the permitted variations are shown in Recommendation US; (e Details of these methods of signalling are laid down in Recommendations U.11 and U.12; that additional signalling standards (types C and D) have been defined for use on international telex netwo
20、rks. 0 signalling in Recommendation U. 15, that it has been necessary to define the rules for interworking Type D signalling with Types A, B and C unanimously declares the view 1 Signalling types 1.1 In general, as far as signalling over international telex circuits is concerned, the outgoing countr
21、y should conform to the signalling requirements of the incoming country. Nevertheless, when in the case of fully automatic service this requirement would entail considerable difficulty, altemative arrangements may be adopted by agreement between the two Administrations concerned. Recommendation U.l
22、(03/93) I ITU-T RECHN*U*L 93 m 4862593 0588737 48T m 1.2 circuit. 1.3 groups-type A and type B - as given in Tables la, Ib and 2. The signals shown in clauses 2 to 10 below shall be employed under the conditions indicated. NOTE - Both the forward and backward path signals are described at the moment
23、 of their emission on the international The Characteristics of the signals defined in clauses 4, 5, 7 and 10 below can be divided into two basic . TABLE laiU.1 international telex circuits terminated on distant automatic switching equipment with semi-automatic working to subscribers Signal Call-conf
24、irmation (see clauses 4 and 5. I) Proceed-to-select (see subclause 5.1) Selection (see clause 6) Call-connected (see clause 7) Busy (see subclause 10.1) Out-of-order, number changed, number unobtainable, etc. (see subclause 10.1) Type A Permanent stop polanty Teleprinter signal(s) Teleprinter signaI
25、(s) Teleprinter signals (Note 1) Teleprinter signals followed by clearing signal Clearing signal normally preceded by teleprinter signals 25-ms puise of stop polarity (between 17.5 and 35 ms) 25-ms pulse of stop polarity (between 17.5 and 35 rns) Dial pulses, or teleprinter signals Stop polarity for
26、 at least two seconds i) 165-260-ms pulse of stop polarity followed by start polarity for 1500 ms (tolerance i 30%) (Note 2) 165-260-ms pulse of stop polarity followed by teleprinter signals and start polarity for 1500 ms (tolerance f 20%) (Note 2) i) i) Permanent start polarity i) 165-260-ms pulse
27、of stop polarity followed by start polarity for 1500 ms (tolerance f 30%) (Note 2) iii) 165-260-ms pulse of stop polarity followed by teleprinter signals and start polarity for 1500 ms (tolerance f 20%) (Note 2) NOTES 1 The teleprinter signals may be preceded by a 150-ms (I 11 ms) pulse of start pol
28、arity. 2 This sequence of signals may be repeated unit a clearing signal is sent over the forward signalling path. However, with transmission systems having significant propagation delay, e.g. satellite or multiplex systems, it may be preferable to prevent such repetitions. 2 Recommendation U.l (03D
29、3) ITU-T RECMN*U*L 73 = 486257L 0588738 316 TABLE lbLJ.1 International telex circuits terminated on distant automatic switching equipment with fully automatic working between subscribers Signal Call-confirmation (clauses 4 et 5) Proceed-to-select (subclause 5. i) Selection (clause 6) Call-connected
30、(clause 7) Call redirection signal (clause 2AJ.41) Busy (subclause 10.1) Out-of-order, number changed, number unobtainable, etc. (subclause 10.1) Changed address interception signal (clause iKJ.41) Permanent stop polarity 40-ms (+ 8 ms) pulse of start polarity Teleprinter signais 150-ms (+ 1 i ms) p
31、uise of start polarity followed by stop polarity for at least 2 seconds and possibly by teleprinter signals Cali connected signai as defined above, followed by the call redirection sequence defined in clause uU.41 Teleprinter signals followed by clearing signal Clearing signal normally preceded by t
32、eleprinter signals Call connected signal as defined above, followed by the changed address interception sequence defined in clause 1KJ.41 25-ms pulse of stop polarity (between 17.5 and 35 ms) 25-111s pulse of stop polarity (between 17.5 and 35 ms) Dial pulses, or teleprinter signals Stop polarity fo
33、r at least 2 seconds Cal connected signai as defined above, followed by the call redirection sequence defined in clause uU.41 i) ii) i) ii) iii) i 65-260-ms pulse of stop polarity followed by start polarity for 1500 ms (tolerance I30%) (Note I) 165-260 ms puise of stop polarity followed by teleprint
34、er signals and start polarity for 1500 ms (tolerance k 20%) (Note 1) Permanent start polarity (Note 2) 165-260-ms pulse of stop polarity followed by start polarity for 1500 ms (tolerance k 30%) (Note 1) 165-260-ms pulse of stop polarity followed by teleprinter signais and start polarity for i500 ms
35、(tolerance I20%) (Note 1) Call connected signal as defined above, followed by the changed address interception sequence defined in clause iKJ.41 NOTES 1 This sequence of signals may be repeated until a clearing signal is sent over the forward signalling path. However, with transmission systems havin
36、g significant propagation delay, e.g. satellite or multiplex systems, it may be preferable to prevent such repetitions. 2 The use of this signal should be avoided if possible. Recommendation U.l (03/93) 3 ITU-T RECMN*U-L 93 Y862591 0588739 252 Signal Call-confirmation (clause 4) Proceed-to-transmi t
37、 (subclause 5.2) Call-connected (clause 7) Busy, out-of-order, number changed and number unobtainable (subclause 10.1) TABLE 2N.I International telex circuits terminated on distant manual switching equipment Type A Permanent stop polarity Teleprinter signals Teleprinter signals Teleprinter signals 2
38、5-ms pulse stop polarity (between 17.5 and 35 ms) Stop polarity followed by teleprinter signals Teleprinter signals Teleprinter signals 2 Free line condition 2.1 The free line is characterized by a permanent signal corresponding to the start impulse in accordance with International Telegraph Alphabe
39、t No. 2 (ITA2) (see the Recommendation cited in i) on the forward and backward signalling paths. 3 Call 3.1 The call is characterized by an inversion to STOP polarity, received on the forward signalling path. Future designs of equipment should not recognize such an inversion as a valid call signal,
40、unless it has existed for a period of greater than 50 milliseconds. 4 Call-confirmation signal 4.1 to prove the continuity of the line and the response of the distant terminal equipment. 4.2 a delay not exceeding 150 milliseconds after the arrival of the calling signal at the receiving end. A call-c
41、onfirmation signal shall be returned over the backward signalling path following the initiation of a call The call-confirmation signal shall be returned by the receiving end as quickly as possible and in any event with 5 Signais preceding selection 5.1 Proceed-to-select signal 5.1.1 In the case of i
42、nternational telex circuits terminated on distant automatic switching equipment that cannot accept the selection information immediately (either after the reception of the calling signal or after the sending of the call-confirmation signal), a distinct proceed-to-select signal shall be returned over
43、 the backward signalling path after the call-confirmation signal, to indicate that the selection information may be transmitted. 5.1.2 signal until the moment when the proceed-to-select signal begins to be sent, should be at least 100 milliseconds. . For type A signalling, the sending duration of th
44、e stop polarity. from the beginning of the call confirmation 5.1.3 For type B signalling, the time interval between the end of the call-confirmation signal pulse and the moment when the proceed-to-select signal begins to be sent, during which the start polarity is sent, should be at least 100 millis
45、econds. 4 Recommendation U.1 (03/93) ITU-T RECMN*U=L 93 4862591 0588740 T74 W 5.1.4 During the busy hour, for 99 calls in 100, the delay in the return by the receiving system of the proceed-to- select signal must not exceed 3 seconds after the reception of the calling signai. (In certain existing ne
46、tworks, this time may be 4 seconds.) 5.1.5 If the automatic switching equipment at the receiving end can receive the selection information immediately after the sending of the call-confirmation signal, the call-confirmation signal shall constitute the proceed-to-select signal. 5.1.6 receiving the ca
47、ll signal, there shall be no proceed-to-select signal. If the automatic switching equipment at the receiving end can receive the selection information at the time of 5.2 Proceed-to-transmit signai 5.2.1 In the case of international telex circuits terminated on a distant manual switchboard, a proceed
48、-ro-rrunsmir signal shall be returned over the backward signalling path following the initiation of a call, to indicate that the teleprinter of the distant operator has been connected to the international circuit. 6 Selection signals 6.1 conformity with Recommendation U.2. The selection signals shou
49、ld be in conformity with International Telegraph Alphabet No. 2 or dial signals in 6.2 be used on international circuits, because of the difficulty in transmitting signals other than figures from dials. In the case of dial selection into a system employing letters in the national numbering scheme, figures only will 6.3 tion No. 30 (figure-shift). In the case of selection into a keyboard selection system, the prepare-for-digits signal the will be combina- 6.4 In those cases where an end-ofselection signal is required, this signal shall be combination No. 26 in figure-shift m
