1、ITU-T RECMN*U=206 93 4862593 0588823 TT3 W INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU TELEGRAPH SWITCHING INTERNATIONAL TELEX SERVICE U.206 (03/93) TECHNICAL REQUIREMENTS FOR INTERWORKING BETWEEN THE INTERNATIONAL TELEX SERVICE AND THE VIDEOTEX SERVIC
2、E ITU-T Recommendation U206 (Previously “CCITT Recommendation”) ITU-T RECMN*U*20b 93 U ilBb259L 0588822 93T 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, operatin
3、g 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, established the topics for study by the IT-T Study Groups which, in their turn
4、, produce Recommendations on these topics. ITU-T Recommendation U.206 was prepared by the IT-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 (ITU), the CCITT ceased t
5、o exist as of 28 February 1993. In its place, the ITLJ 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 Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector.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 Recommendati
6、on, no change has been made in the text to references containing the 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
7、 administration 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, inclu
8、ding photocopying and microfilm, without permission in writing from the ITU. ITU-T RECMN*Um20b 93 m 4862591 0588823 876 m CONTENTS 1 Introduction 2 Basic interworking service . 2.1 General 2.2 Access methods for interworking . 3 Telex-to-Videotex direction . 3.1 One-stage selection . 3.2 Two-stage s
9、election Interworking in the Videotex-to-telex direction . 4.1 Delivery procedure to telex from a one-stage TelexNideotex Conversion Facility (VTXCF) 4.2 4.3 Notifications to the Videotex user Annex A - Reactions to abnormal conditions during text input from telex . 4 Delivery procedure to telex fro
10、m a two stage TelexNideotex conversion facility (VTXCF) A . 1 A.2 A.3 A.4 AS A.6 A.7 A.8 The telex subscriber pauses during input of address information (applicable for two-stage access The telex subscriber pauses during or before input of his message The telex subscriber sends a WRU signal to the V
11、TXCF during text input . The telex subscriber sends text after an End Of Transaction (EOT) signal (applicable for two- stage access only) . The telex subscriber clears after an End Of Transaction (EOT) signal before he receives the Input Message Acknowledgement (IMA) signal (applicable for two-stage
12、 access only) . The telex subscriber sends combinations 6, 7 or 8 in figure case . The telex subscriber sends combination 10 in figure case (“BELL“) . Storage capacity overflow in the VTXCF only) Recommendation U.206 (03/93) Page 1 1 1 1 2 2 3 4 4 5 6 6 6 6 6 7 7 7 7 7 ITU-T RECMN*U.20b 73 48b2591 0
13、588824 702 Recommendation U.206 TECHNICAL REQUIREMENTS FOR INTERWORKING BETWEEN THE INTERNATIONAL TELEX SERVICE AND THE VIDEOTEX SERVICE (Helsinki, 1993) 1 Introduction 1.1 service and the videotex service, using a TelexNideotex Conversion Facility (VTXCF). 1.2 Other relevant Recommendations are: Th
14、is Recommendation defines the technical requirements for interworking between the International Telex - - - - - F.59, F.60, F.69 and other F-series Recommendations on the International Telex service aspects: F.80 on general service aspects for interworking with the International Telex Service; F.300
15、 on Videotex service aspects; U.200 on general technical aspects for interworking with the International Telex service; other U-, R- and S-series Recommendations on switching, terminal and transmission aspects of the International Telex Service; T-Series Recommendations on Videotex technical aspects
16、. - 2 Basic interworking service 2.1 General Interworking between the telex and the videotex service requires storage in both directions. The location of the storage, necessary for interworking is a national matter. The telex-to-Videotex direction is described in clause 3 and the Videotex-to-telex d
17、irection is described in clause 3. 2.2 Access methods for interworking The following methods to access the videotex service from the telex service can be provided: a) b) The method of interworking is in the telex-to-videotex direction normally based on store-and-retrieve one-stage selection is descr
18、ibed in 3.1 ; two-stage selection is described in 3.2. 2.3 principles. For calls in the videotex-to-telex direction store-and-forward principles apply. It is the responsibility of the VTXCF to perform the following conversions: - service procedures; - transmission rate; - code (see Note); - line len
19、gth; - insertion of necessary control characters (figure-shift, letter-shift, carriage return, line feed). NOTE - In the videotex-to-telex direction, the videotex terminal (or the user) shall restrict each message to the character repertoire of ITA2. However, where the VTXCF receives characters out
20、of the ITA2 repertoire, these characters shall be converted in accordance with Recommendation S. 18. 2.4 Recommendation U.206 (03/93) 1 ITU-T RECMN*U-ZOb 93 W 48b259L 0588825 649 W WRU (Note 5) Answerback (Note 5) 4 Clear b 2.5 The service requirements are described in Recommendation F.86. T X C F 3
21、 Telex-to-Videotex direction 3.1 One-stage selection The procedure to be used is the same as for a normal telex call. Figure 1 and the appending notes show the procedure in detail. International telex sernce Selection (Note 1) 7 Answerhac k (Note 3) I Videotex service Validation (Note 2) I Result (N
22、ote 2) I 4 Delivery (Note 6) v I D E O T E X S E R V I C E Retriebe u V T0900630-90/do 1 FIGURE 1/U.2 One-stage selection procedure 3.1.1 Note 1 to Figure 1 The total selection information (including the F.69 destination code and a possible national CF-prefix) for the videotex address shall not cons
23、ist of more than 12 digits. This requires the registration of each videotex user who wants to communicate with telex subscribers and assign to him a telex number. 3.1.2 Note 2 to Figure 1 Validation is done in the videotex service or in the VTXCF (at the point of registration) to get the following i
24、nformation: - - if the selection corresponds to a videotex user; status of the videotex user (could be “ABS” on a registration basis). If the validation fails, the VTXCF shall return the service signal NP and clear the call. In case the videotex user is in a registered “not ready” condition, the VTX
25、CF shall return the appropriate service signal (in accordance with Recommendation U.45) to the calling telex subscriber and clear the call. A positive validation result provides the necessary information for the individual videotex users answerback. 3.1.3 The answerback code allocated to the videote
26、x user shall be in accordance with Recommendation F.74 and shall contain the complete national call number. Note 3 to Figure 1 2 Recommendation U.206 (03/93) ITU-T RECMN*U.Zb 93 W 4862591 0588826 585 W The “abbreviated name” of the answerback could be either: - - “VTX. registered for each videotex u
27、ser; or 3.1.4 After provision of the called answerback the caller may commence transmission. See Annex A (abnormal conditions) for the reaction of the VTXCF to characters and character strings which are not possible to be displayed on the videotex side. Note 4 to Figure 1 3.1.5 If the telex subscrib
28、er sends a WRU signal in any stage of the message input the VTXCF shall return the answerback allocated to the videotex user as in 3.1.3 above. Note 5 to Figure 1 3.1.6 After reception of the clearing signal (normal clearing procedures), the VTXCF makes the message available for retrieval. Note 6 to
29、 Figure 1 A notification with the information about the presence of a received telex message should be provided to the videotex user as soon as he logs-in to this service. 3.1.7 Note 7 to Figure 1 The VTXCF may be part of the Videotex service. 3.2 Two-stage selection Interworking in the telex-to-vid
30、eotex direction, using two-stage selection, is described in Figure 2 and the appending notes. International telex service Answerback I Videdex service r- IV E Ix = Retrieve FIGURE UU.206 Two-stage selection access to a TeledVideotex Conversion Facility (VTXCF) 3.2.1 Normal telex procedures apply for
31、 call Set-up. Note 1 to Figure 2 Recommendation U.206 (03/93) 3 ITU-T RECMN*U.206 93 W 48b2591 0588827 411 W 3.2.2 Note 2 to Figure 2 Coding of the VTXCF answerback is the following: “Figs”, “CR, “LF, VTXCF National Number, “Lttrs”,“SP”,VTXCF, “SP, O O means the TNIC, e.g. “A” for Austria. To be fil
32、led with “Lttrs” according to Recommendation F.60. Example: 751200 vtxcf a. If the national telex number of the VTXCF exceeds 6 or 7 digits, the mnemonic part of the answerback may be reduced to VTX. A WRU signal may be sent in accordance with Recommendation S.23. 3.2.3 Note 3 to Figure 2 The prefer
33、red selection input format is: “CR,“LF”,NationaI address of the videotex user,“+”. “CR,“LF” is optional input. If selection input does not commence within three seconds the VTXCF shall return the service code GA. 3.2.4 Validation is done by confirming the existence of the called address. The maximum
34、 duration for this validation is three seconds. Note 4 to Figure 2 A positive validation result is not reflected to the telex subscriber. 3.2.5 The telex subscriber should start the message input after the address input. If the validation result (see 3.2.4) is negative, the VTXCF shall stop the mess
35、age input by sending a sequence of “ TTT.” characters, followed by an “NP service signal. If the telex subscriber does not stop transmission, the VTXCF shall disconnect. See Annex A (abnormal conditions) for the situation where text input does not commence or is interrupted, and for the reaction of
36、the VTXCF to characters or character strings which are not possible to be displayed on the videotex side. Note 5 to Figure 2 3.2.6 The VTXCF should consider a sequence of four times “+” (+i-) as End of Transaction (EOT). Alternatively, the telex subscriber should exchange answerbacks and clear. Note
37、 6 to Figure 2 3.2.7 In case the telex subscriber used EOT, an ITD in the form of “ITD - MESSAGE STORED is sent to the telex subscriber after completion of the transaction to the videotex data base. Note 7 to Figure 2 4 The videotex service user may send a message to a terminal connected to the tele
38、x network in accordance with the principles contained in Recommendation F.300. The method of depositing a message on the part of the videotex service user for delivery to telex is a national matter. Interworking in the Videotex-to-telex direction 4.1 A message, received from a videotex user, shall a
39、ppear like a normal telex message to the telex subscriber. Delivery procedure to telex from a one-stage TelexNideotex Conversion Facility (VTXCF) Figure 3 and the appending notes show the procedure in detail. 4 Recommendation U.206 (03/93) ITU-T RECMN*U.ZDb 93 m 4862593 0588828 358 m Videotex serwce
40、 International telex semice Call (Note 1 ) Answerback (Note 2 j Answerback (Note 3) CI Message ) Y W RU signal Answerback (Note 4) * Answerback (Note 3) Clearing b T090065i-9i/a)3 FIGURE 3KJ.206 Delivery procedure to telex from a one-stage TelexNideotex Conversion Facility (VTXCF) 4.1.1 Call establi
41、shment is done using normal telex procedures. Note 1 to Figure 3 4.1.2 The telex answerback shall be evaluated in accordance with Recommendation U.75. If the evaluation leads to a negative result, the VTXCF shall disconnect and consider the delivery attempt as unsuccessful. If the call is unsuccessf
42、ul, reattempts shall be made in accordance with Recommendation U.40, up to a limit of two hours total. Note 2 to Figure 3 4.1.3 See 3.1.3. Note 3 to Figure 3 4.1.4 The answerback received shall be compared with the one in Note 2. In case of a mismatch, a second WRU signal is sent to receive the answ
43、erback of the called subscriber again. If there is again a mismatch, the delivery attempt is considered as unsuccessful. A header ?POSSIBLE DUPLICATE MESSAGE? shall be added to the message for subsequent delivery: Note 4 to Figure 3 - - - if interruption occurred during transmission of the message;
44、if backward keying occurred during transmission of the message; if the final answerback was different from the one received at the beginning of the call. 4.2 The procedure is the same as described in 4.1 with the following exceptions: Delivery procedure to telex from a two stage TelexNideotex Conver
45、sion Facility (VTXCF) - - the answerback provided to the telex side shall be the VTXCF answerback as escribed in 3.2.1; a herald, indicating the source of the message and the recall address should be added at the beginning of the message in accordance with Recommendation F.86. Recommendation U.206 (
46、03/93) ITU-T RECMN*U=20b 93 W 4862591 0588829 294 4.3 Notifications to the Videotex user 4.3.1 cases: The VTXCF shall generate notifications and shall make them ready for retrieval by the Videotex user in both - successful delivery; - unsuccessful delivery. 4.3.2 Notification messages should include
47、 at least the following information - message reference number; - datehime of notification; - requested telex address (selection); - - expected telex answerback; - - duration and charge (optional): - received telex answerback (also, if applicable, in case of non-delivery); datehime of delivery or da
48、tehime of final delivery attempt, as relevant: reason for non-delivery of telex message, if applicable (e.g. received telex service signal, answerback check failure). 4.3.3 The format of the notification and the method of the return to the videotex user is a national matter. Annex A Reactions to abn
49、ormal conditions during text input from telex (This annex forms integral part of this Recommendation) A.l The telex subscriber pauses during input of address information (applicable for two-stage access only) If there is a delay greater than 15 seconds before starting the address input or between any characters within the address input, the VTXCF shall return an “NP service message and clear. A.2 The telex subscriber pauses during or before input of his message a) If there is a delay greater than 30 seconds before starting the message input the VTXCF shall send a
