1、 - ITU-T RECflN*U-45 93 486259% 0588843 664 M INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU TELEGRAPH SWITCHING PARTICULAR SIGNALLING FACILITIES u.45 (03/93) RESPONSE TO THE NOT-READY CONDITION OF THE TELEX TERMINAL ITU-T Recommendation U.45 (Previously
2、“CCIlT Recommendation”) ITU-T RECMN*U.45 73 m 48b259L 0588844 5T0 = 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 questions and issuing Recom
3、mendations 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 Recommendations on these topi
4、cs. ITU-T Recommendation U.45 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 (U), the CCITT ceased to exist as of 28 February 1993. In its pla
5、ce, the IT 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 Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector.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 has been made in the text to r
6、eferences containing the acronyms “CCIlT, 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 and a recognized operating
7、agency. In this Recommendation, the expression “Administration” is used for conciseness to indicate both a O IT 1994 Ail 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 per
8、mission in writing from the ITU. ITU-T RECMN*U.45 93 = 4862593 0588845 Li37 CONTENTS Page 1 Definition . 1 2 Scope 1 Call attempts to terminals already in the not-ready condition Activation of the not-ready condition during an established connection . 3 4 1 2 Recommendation UA5 (03/93) ITU-T RECMN*U
9、.45 93 m 4862591 0588846 373 Recommendation U.45 RESPONSE TO THE NOT-READY CONDITION OF THE TELEX TERMINAL (Melbourne, 1988; revised Helsinki, 1993) The CCIT, considering (a) program-controlled exchanges in the international telegraph, telex and gentex networks; (b) terminal; the increasing use of m
10、odem electronic terminals, telex automatic emitting devices (TAEDs) and stored- the desirability of standardizing the network and terminal responses to the various not-ready conditions of the and recognizing the need to keep the response as short as possible in order to avoid unnecessary charging; u
11、nanimously recommends the adoption of the following procedures in response to the not-ready condition of the telex terminal in new equipments and as far as possible in existing equipments. 1 Definition 1.1 The following term used in this Recommendation is defined as follows: the not-ready condition
12、of the telex terminal: The status of a terminal which prevents the return of the call connect signal or answerback sequence in response to a valid incoming call signal or WU signal respectively. Alternatively, the status which develops within a terminal during an established connection as a result o
13、f the exhaustion of the printing paper, or equivalent recording medium, and which results in premature clearing of the connection. 2 Scope The provisions of this Recommendation apply only to printed service signals. 3 Call attempts to terminals already in the not-ready condition 3.1 For networks whi
14、ch do not utilize the additional information characters allowed by 10.1.2AJ.1, then a call attempt to a terminal in the not-ready condition and connected to that network shall receive the standard service signal DER. constructed in accordance with Table 1KJ. 1 and 10.1.2KJ. 1. It should be noted, ho
15、wever, that some Administrations use the standard service signal ABS to signal the not-ready condition as a result of loss of power at the called terminal. 3.2 An an exception to the above, the service codes listed in Recommendation F.131 shall be used when a call attempt is made from the internatio
16、nal telex network to a ship-earth station participating in the maritime mobile service or the maritime mobile-satellite service and which is not capable of accepting the call. 3.3 For networks which can utilize these additional information characters, then a call attempt to a terminal in the not-rea
17、dy condition and connected to that network shall receive the expanded version of the standard service signal DER, constructed in accordance with Table 1KJ.1 and 10.1.2AJ.1. 3.4 where the caracter strings PFL, EXM and NAB have meanings as listed in 4.1.1F.60. The additional information characters sha
18、ll be in accordance with Table 1 for the not-ready conditions listed, Recommendation U.45 (03/93) 1 - ITU-T RECMN*U.45 93 = 4862591 0588847 20T 3.5 For call re-attempts in accordance with Recommendation U.40, it is important that there is no confusion between the basic and expanded form of the servi
19、ce signal. For this reason, the format of the service signal train specified in 1O.l.uU.l shall be rigidly applied, where the standard service signal is delimited by a carriage-return and line-feed sequence at beginning and end. The standardization of a specific response to the PFL. EXM and NAB cond
20、itions is for further study. 3.6 It should be noted that where an expanded form of a U.l service signal transits networks which apply signalling conversion rules in accordance with Recommendation U. 15, then the additional information characters will be discarded by the conversion process and only t
21、he standard service text (i.e. c I 1 DER t E) will be translated by the Type D transit centre. 4 Activation of the not-ready condition during an established connection 4.1 During an established connection, the transition to the not-ready condition in the receiving terminal will generally be indicate
22、d by an escalation from a PAPER LOW to a PAPER OUT situation. For terminals which use electronic memory as the recording medium, this will be equivalent to STORE LOW and STORE FULL conditions. The procedures to be applied during this transition are a national matter. 4.2 On reaching a PAPER OUT (or
23、equivalent) condition, one of the following procedures should be applied: 4.2.1 The receiving terminal shall send a clearing signal to initiate immediate clearing of the connection. 4.2.2 be activated. Preferably, in new terminals and as far as possible in existing terminals, the following sequence
24、of events will 4.2.2.1 Interrupt the incoming text as per Recommendation S.4. 4.2.2.2 Send the following character sequence at automatic speed t = 4 EXM t E to indicate exhaustion of the recording medium. 4.2.2.3 Send the clearing signal to initiate clearing of the connection. (See Table 1.) 4.2.2.4
25、 forward transmission is for further study, The reaction of automatic calling devices (terminals, CF. SFU) to the receipt of EXM and clearing during 4.2.3 initiate clearing in accordance with 4.2.1 above. If the transmitting terminal fails to respond to the request to stop transmission, then the rec
26、eiving terminal shall 4.3 Further incoming calls to this terminal will be handled in accordance with clause 3 above. 4.4 recommended that the procedures of 4.2.2.2 and 4.2.2.3 be applied. In the situation where a transmitting terminal is about to reach a PAPER OUT condition, then it is 2 Recommendat
27、ion U.45 (03/93) ITU-T RECMN*U.45 93 48b259L 0588848 L4b TABLE 1N.45 Response to the not-ready condition in the telex terminal Not-ready condition of terminai During established connection: imminent exhaustion of printing paper (or equivalent recording medium) During call Set-up: (Note i) - Power fa
28、ilure - Lack of text recording medium - Failure of answerback Effect at exchange Response of terminai a) Initiate clearing as per national requirements, or b) Interrupt i/c text as per Recommendation S.4; Transmit the sequence t = 4 EXN t E; Initiate clearing as per national requirements. (Note 3) N
29、o current Non-receipt of call connect Non-receipt of valid answerback sequence NOTES 1 2 3 4 See also 3. I. Or technical failure presenting the same conditions at the exchange. Service signal constructed in accordance with 10.1.2R.J. 1. Should the incoming text fail to stop, then clear as per a). Signai sent by exchange None (Note 2) 4 PFL t = 1 DER t = 1 EXM t 3. DER t = 1 NAB t 1 DER t = (Note 4) Recommendation U.45 (03/93) 3
