1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU TELEGRAPH SWITCHING PARTICULAR SIGNALLING FACILITIES U .40 (03/93) REACTIONS BY AUTOMATIC TERMINALS CONNECTED TO THE TELEX NETWORK IN THE EVENT OF INEFFECTIVE CALL ATTEMPTS OR SIGNALLING INCIDENTS ITU-T Recom
2、mendation U.40 (Previously “CCITT Recommendation”) ITU-T RECMN*U-40 73 m 48b2-591 0588765 344 m FOREWORD The ITU 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
3、 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, established the topics for study by the ITU-T Study Groups which, in their turn, produce R
4、ecommendations on these topics. ITU-T Recommendation U.40 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 Intemational Telecommunication Union (ITU), the CCIT ceased to exist as of
5、28 February 1993. In its place, the ITU Telecommunication 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 Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector.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 h
6、as been made in the text to references containing the acronyms “CCIT, 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 ITU structure. 2 telecommunication administration
7、 and a recognized operating agency. In this Recommendation, 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 photocopyi
8、ng and microfilm, without permission in writing from the ITU. ITU-T RECMN*U.YO 93 m 4862591 05887bb 280 m CONTENTS 1 Ineffective outgoing call . 1.1 1.2 1.3 1.4 1.5 1.6 Non-return of the call-confirmation andor proceed-to-select signal(s) . Slow or incomplete selection No response after selection .
9、Ineffective attempts followed by service signals Ineffective calls characterized by a clearing signal without a preceding service signal . Reception of an answerback . 1.7 Possible terminal configuration 2 Ineffective incoming calls 2.1 False calls 3 Incidents following call set-up . 3.1 Idle circui
10、t without clearing signal . 3.2 No clear-confirmation . Recommendation U.40 (03/93) Page 1 1 1 1 1 2 2 3 3 3 3 3 3 i ITU-T RECMN*U.40 93 W 4862591 05887b7 117 W Recommendation U.40 REACTIONS BY AUTOMATIC TERMINALS CONNECTED TO THE TELEX NETWORK IN THE EVENT OF INEFFECTIVE CALL ATTEMPTS OR SIGNALLING
11、 INCIDENTS (Geneva, 1980; amended at Malaga-Torremolinos, 1984; and at Melbourne, 1988 and Helsinki, 1993) The CCITT, considering (4 until the call has been set up; (b) that equipment capable of automatically originating calls in the telex network can repeat unsuccessful calls that unlimited repetit
12、ion of call attempts may cause congestion in the telex network; (cl tolerable numbers of repeated call attempts and simultaneous calls; that manufacturers of automatic terminals for connection to the telex network should be given guidance on unanimously declares the following view 1 Ineffective outg
13、oing call 1.1 1.1.1 and/or the proceed-to-select signal(s) have not been received from the network, the terminal sends the clear signal. Non-retum of the call-confirmation and/or proceed-to-select signal(s) The call signal could be maintained for a maximum period of 20 s. If, within this period, the
14、 call-confirmation 1.1.2 A further call attempt must not be made within a minimum period of 20 s. 1.1.3 specifying the nature of the fault. After three such ineffective attempts, the incident should be reported to the staff at the terminal installation, 1.2 Slow or incomplete selection 1.2.1 Once th
15、e terminal has sent a call signal and has received the call-confirmation and/or proceed-to-select signal(s), transmission of the selection digits must commence within a period of between 0.5 and 7 s, depending on the national network. If this delay is exceeded, the network may clear. 1.2.2 7 s occur
16、s, between two selection digits. The same procedure applies in the event of incomplete selection by the terminal or, if an interval longer than 1.3 No response after selection 1.3.1 within 60 s, it may send the clear signal. This delay may be increased to 120 s for international calls. If, after sel
17、ection has been completed (but before the call has been set up), the terminal receives no signais 1.3.2 Further attempts may be made in accordance with 1.1.2 and 1.1.3 above. 1.4 Ineffective attempts followed by service signals 1.4.1 OCC 1.4.1.1 If, after initiating a call, the terminai receives an
18、OCC service signal followed by clear, it must wait at least 60 s before repeating the attempt. If OCC is received again, then second, third and fourth attempts shall be permitted at 180-second intervals. Recommendation U.40 (03/93) 1 ITU-T RECMN+U.40 93 m 4862591 05887b8 053 1.4.1.2 If the distant t
19、erminal is still unavailable after a maximum of four such reattempts, this should be reported to the staff at the terminal installation indicating the number called and the service code received. Ten series of a maximum of four reattempts per series may be carried out at intervals between 480 and 36
20、00 s, between each series. 1.4.1.3 abandoned as far as the automatic terminal is concerned. Should the distant terminal remain unavailable after these call series, this should be reported and the call 1.4.2 NC 1.4.2.1 before repeating the attempt. If, after initiating a call, the terminal receives a
21、n NC service signal followed by clear, it must wait at least 60 s 1.4.2.2 If the distant terminal is still unavailable after a maximum of four such reattempts, this should be reported to the staff at the terminal installation indicating the number called and the service code received. Ten series of
22、a maximum of four reattempts per series may be carried out at intervals between 480 and 3600 s, between each series. 1.4.2.3 as far as the automatic terminal is concerned. Should this second series still fail to reach the distant terminal, this should be reported and the call abandoned 1.4.3 NA, NP,
23、 NCH or the service code CI 1.4.3.1 reattempt may be made after a minimum period of 2 s. If, after initiating a call, the terminal receives an NA, NCH or NP service signal followed by clear, only one 1.4.3.2 In the event of a second failure due to a service signal specified in 1.4.3.1, the terminal
24、should abandon the call and report the incident to the staff at the terminal installation indicating the number called and the service code received. 1.4.3.3 should also be applied. If the terminal receives the service code CI followed by clear, the procedure described in 1.4.3.1 and 1.4.3.2 1.4.4 D
25、ER, ABS 1.4.4.1 30 minutes before repeating the attempt. If after initiating a call, the terminal receives a DER or ABS service signal followed by a clear, it must wait 1.4.4.2 then wait two hours before repeating the series of two attempts spaced 30 minutes apart. If the first repeated attempt is u
26、nsuccessful, another attempt may be made 30 minutes later. The terminal must 1.4.4.3 delay of 15 minutes to 2 hours. A total of 5 such series may be made with two attempts per series. If the distant terminal is still unavailable after these attempts, further series of attempts can be made after a 1.
27、5 Ineffective calls characterized by a clearing signal without a preceding service signal 1.5.1 service signal, it must wait 2 s before a second attempt. If after having made a call, the terminal equipment receives a clearing signal without previous reception of a 1.5.2 after a delay of 15 minutes.
28、If the same phenomenon occurs three times in succession, a second series of three calls may be made again 1.5.3 If the second series of calls produces the same result, the terminal equipment should definitively abandon the call and report the incident to the staff at the terminal installation indica
29、ting the number called and that no service code was received. 1.6 Reception of an answerback 1.6.1 signal and repeat the call only once after a period of 2 s. If, after having made a call, the terminal equipment receives an incorrect answerback, it may send the clearing 1.6.2 If the second attempt f
30、ails in the same way, the terminal should abandon the call and report the incident to the staff at the terminal installation, indicating the number called and the fact that the expected answerback code was not received. 2 Recommendation U.40 (03/93) ITU-T RECMN+U=40 93 48b259L 05887b9 T9T = 1.7 Poss
31、ible terminal configuration 1.7.1 Single telex line 1.7.1.1 with Table 1. Single message, single address - in this case the handling of ineffective call attempts shall be in accordance 1.7.1.2 with Table 1 on a per address basis. Single message, multi-address - in this case the handling of ineffecti
32、ve call attempts shall be in accordance 1.7.1.3 Multi-message, single addresss - in this case the handling of ineffective call attempts shall be in accordance with Table 1 for the first message. If this message is considered undeliverable, then all others are deemed to be undeliverable and it is rec
33、ommended that no call attempts should be made to this telex address in respect of the remaining messages. 1.7.1.4 with Table 1 on a per message per address basis. Multi-message, multi-address - in this case the handling of ineffective call attempts shall be in accordance 1.7.2 Multiple telex line 1.
34、7.2.1 If an automatic terminal equipment can initiate simultaneous call attempts on a number of outgoing lines, the number of such call attempts in progress at any one time shall not exceed a maximum prescribed by the Administration concerned. 1.7.2.2 In no case shall a multiple-line terminal equipm
35、ent be allowed to present the same call simultaneously on more than one telex line. Moreover, the periodicity of a given repeated call and the number of attempts to be made in case of failure shall apply to this terminal equipment as indicated in Table 1, irrespective of whether the call is presente
36、d on the same line or on different lines. 2 Ineffective incoming calls 2.1 False calls 2.1.1 The terminal should disregard any “call” signal from the network that does not exceed 50 ms in duration. 2.1.2 network, it should return the clear signal to the network. If the terminal receives no signals w
37、ithin a period of up to 30 s after it has recognized a call signal from the 3 Incidents following call Set-up 3.1 Idle circuit without clearing signal 3.1.1 Earring prior agreement to the contrary, if no signal is received after the beginning of the call or if the distant correspondents transmission
38、 stops during an incoming call (i.e. steady stop polarity on the incoming path) for a period of more than 2 minutes, the receiving terminal may clear the call and report the incident to the staff at the terminal installation, indicating the nature of the suspected fault and, if possible, the nuinber
39、 of the distant subscriber. 3.2 No clear-confirmation 3.2.1 Should the network fail to return the clear-confirmation signal after the terminal has been sending a clear signal for 10 s or more, the terminal should report the incident (giving the time at which it occurred) and withdraw the circuit fro
40、m service until the necessary action has been taken. Recommendation U.40 (03/93) 3 ITU-T RECMN*U.40 93 W 48b259L 0588770 701 W Relevant point 1.1 1.3 1.4.1 1.4.2 1.4.3 1.5 1.6 2.1 3.1 3.2 TABLE 1N.40 Summary of the required reactions to ineffective call attempts and signalling difficulties Symptoms
41、Outgoing calls No call-confirmation andor proceed-to-select No response after selection: national calls international calls occ NC ABS, NA, NP, NCH, DER or CI Clearing without a service signal Incorrect answer-back Incoming calls No signals after a “call” signal Conditions afer call establishment Id
42、le circuit (steady Z) Conditions afer clearing No clear-confimation Time-out or delay before clearing (seconds) 20 60 120 - - - - O 30 120 10 Maximum number of reattempts per series 3 3 3 4 4 1 3 2 - - - Number of series 1 1 1 10 10 1 2 1 - - - Minimum internal between series (seconds) - - - 480 to
43、3600 480 to 3600 - 900 - - - - Minimum interval between attempts (seconds) 20 20 20 6Oa) 180 a) 60 2 2 2 - - - *) In the case of OCC, the period between the original attempt and the first reattempt should be 60 s. Between subsequent reattempts this period should be extended to 180 s. VOTES I Where v
44、arious combinations of service signais are encountered, the equipment making the reattemtps shall obey the rules ippropriate to the last service signal encountered. In no case, however, shall the total number of reattempts on any one call :xceed 12. I This Recommendation is subject to amendment in the light of traffic experiments undertaken by Administrations. 4 Recommendation U.40 (03193)
