1、ITU-T RECMN+U-20L 93 4862593 0594200 012 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU TELEGRAPH SWITCHING INTERNATIONAL TELEX SERVICE u.201 (03/93) INTERWORKING BETWEEN THE TELETEX SERVICE AND THE INTERNATIONAL TELEX SERVICE ITU-T Recommendation U.201 (
2、Previously “CCITT Recommendation”) FOREWORD The ITU Telecommunication Standardization Sector (T-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 view to s
3、tandardizing 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 topics. ITU-T Recommendation U.201 was
4、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 (ITU), the CCIT ceased to exist as of 28 February 1993. In its place, the IT Telecommunication Stan
5、dardization Sector (IT-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 Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector.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 acronyms
6、“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 Recommendation, the
7、 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 the ITU. I
8、TU-T RECMN*U*20h 93 48b259h 0594202 995 CONTENTS 1 Introduction 2 Basic interworking service . 2.1 Types of interworking . 2.2 Methods of interworking Telex access to a conversion facility (CF) . 3.2 Two-stage selection 3 3.1 One-stage selection . Delivery procedure to Teletex from a CF 4.1 Service
9、principles 4.2 Text delivery . 4 Annex A - Reactions to abnormal conditions during the telex input . A . 1 A.2 A.3 A.4 AS A.6 A.7 A.8 A.9 A.10 A.11 Telex connection clearing without the end of input signal . Telex subscriber pausing during input of address information . Telex subscriber stopping tra
10、nsmission without sending the end of input signal . Telex subscriber sending a WRU signal to the conversion facility during text input . Telex subscriber sending a text after the end of input signal acknowledgement signal . Telex subscriber clearing after the end of input signal and before the input
11、 message Telex subscriber sending national variants of ITA2 characters (figure shift characters of F, G and H) . The conversion facility detecting signal distortion during text input . CFs storage capacity overflow during telex message input Telex subscriber sending a bell signal Request of optional
12、 facilities, when not provided by the CF Recommendation U.201 (03/93) Page 1 1 1 1 2 2 5 14 14 14 16 16 16 16 16 16 16 16 16 17 17 17 1 ITU-T RECNN*Um20L 93 = 4862591 0594203 821 H Recommendation U.201 INTERWORKING BETWEEN THE TELETEX SERVICE AND THE INTERNATIONAL TELEX SERVICEi) (Melbourne, 1988; r
13、evised Helsinki, 1993) 1 Introduction 1.1 the international telex service. 1.2 service. The other Recommendations are: This Recommendation defines the procedures to be followed for interworking between the Teletex service and This Recommendation is one of the series which define interworking between
14、 the telex service and the Teletex a) Recommendation F.200 Teletex service. b) Recommendation T.390 Requirements for interworking with the telex service. c) Recommendation F.201 Interworking between the Teletex service and the telex service - General principles. 2 2.1 2.1.1 2.2 2.2.1 Basic interwork
15、ing service Types of interworking Interworking between the Teletex service and the telex service consists of two directions: a) b) the telex to Teletex direction; the Teletex to telex direction. Methods of interworking considering: a) b) c) that the Teletex service can be provided upon various netwo
16、rks (see 2E.200); that an Administration2) can provide the Teletex service on more than one network (e.g. PSTN and PSPDN, etc.); that the technical constraints of the existing networks (e.g. numbering plans, etc.), the two following methods of interworking between the telex service and the Teletex s
17、ervice can be provided: i) interworking with one-stage selection; ii) interworking with two-stage selection. The service requirements of each method are described in Recommendation F.201. 2.2.2 1 Throughout this Recommendation, the term “telex” should be interpreted as referring exclusively to “the
18、international telex 2, Or a recognized private operating agency. service”, as described in Recommendations F.59 and F.60. Recommendation U201 (03/93) 1 ITU-T RECMNtU.203 93 4862593 0594204 7b8 = Teletex procedires including return of answerback code (Note 2) and clearing 4 * Teletex procedires 4 I 3
19、 Telex access to a conversion facility (CF) 4 Teletex answerback (Note 9) Cleating 3.1 One-stage selection Delimy Message outpit Clearing Recommendation F.201 describes the service principles for this method of interworking. 3.1.1 Access from a manual telex terminai Interworking in the telex to Tele
20、tex direction using one-stage selection, in case of manual terminals, is described in Figure 1 and associated Notes. Telex side cal I (Note 1) f procedures Normal telex Call connected Teletex answerback (Note 3) Calling telex answerback (Note 4) 4 1. WRU sigial (Nue 4) Teletex answerback (Note 41 Me
21、ssage input (Nue 5) Y + WRU signal (Note 6) Teletex answerback A I - End of input (+) (Note 7) MOM INote 81 Teletex side I conversion facility FIGURE 1N.201 Interworking in the telex-teTeletex direction using one-stage selection procedure (case of manual telex) 2 Recommendation U.201 (03/93) ITU-T R
22、ECMNMU-ZOL 93 4862573 0594205 bTLI = .It= Notes relative to Figure 1: 1 2 3 The total selection information should not exceed i 2 digits. See Recommendations T.390 and U.70. If the validation call is unsuccessful, the appropriate service signal in The Teletex answerback sent to the telex subscriber
23、is a rearranged Teletex terminal identification, as follows: accordance with Recommendation U.70 should be returned to the calling telex subscriber followed by the clear signal. Part 2 The length of the Teletex answerback is set to 20 characters, the eventual unused positions are filled with “k acco
24、rding to Recommendation F.60. As far as possible, the mnemoric part is included in the Teletex answerback. Examples of TTX-A/B: 4 The CF shall accept the possible occurrence of an extra WRU signal at this stage. The answerback returned by the CF is the Teletex answerback obtained during the validati
25、on call. (See Note 3.) Additionally, the CF shall accept the possible receipt of the answerback of the calling telex subscriber at this stage, either before the WRU signal described here or following transmission or the Teletex answerback. 5 6 The CF shall wait at least 15 seconds for the message in
26、put. See Annex A for abnormal conditions during text input. i) ii) i) ii) i) This procedure is recommended but not mandatory. (See Recommendation F.60.) The answerback returned by the CF is the Teletex answerback obtained during the validation call. (See Note 3.) The end of input (EOI) signal is the
27、 plus symbol (ITA No. 2 combination No. 26 Figure shift mode) repeated four times (+ + + +). This EO1 signal need not be transferred to the Teletex side. If the caller clears without the EO1 signal, the network will endeavour to deliver the message as received. However, customers must be clearly war
28、ned that the network cannot guarantee delivery in these circumstances. The CF shall wait 800 ms for WRU signal after EOI. If no WRU signai is received within this period, the terminal is considered as a manual one. A MOM signal is then sent by the CF at each call attempt. If a WRU signal is sent by
29、the telex terminal within this period the terminai is considered as a telex automatic emitting device. When the EO1 signal is received, the conversion facility shall immediately establish the delivery call to the Teletex terminal. In the case of unsuccessful calls on the PSPDN and CSPDN, the convers
30、ion facility shall make several attempts with five-second intervals measured from the end of one attempt to the beginning of the next. At each attempt, the MOM signal followed by service signals defined in Recommendation U.70, if appropriate, shall be sent to the waiting telex terminal. As a whole,
31、the telex line is not to be. held for a period exceeding 30 seconds. If all these attempts are unsuccessful, the conversion facility shall send the service message ITL + TTX + 0 (ITL - Ill transmit later) to the waiting telex terminai and clear down. it shall then be the responsibility of the Admini
32、stration operating the conversion facility to effect delivery of the message by whatever means are available. This answerback returned by the CF is the Teletex answerback obtained during the delivery call to the Teletex terminai and having the same format and content as described in Note 3. This ans
33、werback is an “on-line” delivery acknowledgement for the telex user. 7 8 ii) 9 Recommendation U.201 (03/93) 3 3.1.2 Access from a telex automatic emitting device (TAED) (Note 1) I b Interworking on the telex to Teletex direction, using one-stage selection, in case of TAEDs is described in Figure 2 a
34、nd associated Notes. Normal telex procedures Deposit Telex side I Callconnected Exchange of telex and Teletex answerbacks (Note 3) 7 WRU signal (Note 4) I -. _. Teletex answerback (Note 4) 4- Conversion facility I International interface Teletex side Teletex procedures including return of answerback
35、 code and clearing (Note 2) -, Teletex procedure (Note 9) b Delivery Message output Clearing b TO901 320-94/402 Within national network concerned FIGURE uU.201 Interworking in the telex-to-Teletex direction using one-stage selection procedure case of Telex Automatic Emitting Devices - (TAEDs) Notes
36、relative to Figure 2: Remark - Taking into account that most of the Notes related to the two figures are similar, the Notes related to Figure 2 only emphasize the differences from Notes to Figure 1. NOTES 1 to 5 6 7 Identical to Notes of Figure 1. Same as Note 7, Figure 1. i) The CF shall wait 800 m
37、s for WRU signal after EOI. The terminal is considered a telex automatic emitting device (TAED) if a WRU signal is sent within this period. The answerback returned by the CF is the Teletex answerback obtained during the validation call (see Note 3) to confirm that the connection still exists. It is
38、not a proof of delivery. No progress signal (e.g. MOM, ITL + TX + 0) will be returned by the CF to the telex automatic emitting device after the EO1 signal. When the EO1 signal is received, the CF should establish immediately a delivery call to the Teletex terminal. i) 8 The CF shall make several at
39、tempts with five-second intervals measured from the end of each attempt to the beginning of the next. It is the responsibility of each Administration operating the conversion facility to effect the delivery of the message by whatever means are available. 4 Recommendation U.201 (03/93) ITU-T RECMN*U.
40、20L 93 = 4862591 0594207 477 Telex procedures NDN (Note 11) Clearing * ledgement 3.2 Two-stage selection 3.2.1 Service principles Clause 4F.201, describes the service principles for this method of interworking. 3.2.2 Access from a manual terminal 3.2.2.1 described in Figure 3 and associated Notes. I
41、nterworking in the telex to Teletex direction, using two-stage selection, in case of manual terminals, is Deposit Telex side I Texi dqposit I +I 1 I IV) I- +- Conversion facility I Teletex side FIGURE 3LJ.201 Interworking in the telex-teTeletex direction using two-stage selection procedure (case of
42、manual telex terminais) Teletex procedures I - Validation I Delivery T090133094/a)3 Recommendation U.201 (03/93) 5 Notes relative to Figure 3 1 An example of telex procedures is: Teletex If a WRU is received by the CF, it shall return its answerback. Coding of the CF answerback is the following: CFN
43、ATIONALNUMBER J, TTx T+-= Up to 7 digits 2 Address input: see 3.2.2.2. 3 4 WRU signal should be sent immediately after the address input. If the returned telex answerback cannot be processed according to Recommendation U.74 and if no telex address was input, and no skipping indication was given see
44、3.2.2.2.1 b), then the CF shall request the telex address with a specific prompt signal: Remark - The telex address input in response to this ADD must be terminated with a “+“, Combination No. 26 of ITA2 in figure shift mode. If a telex address is not received within I5 seconds after the prompt sign
45、al ADD has been sent. the CF should proceed by sending back a GA signal. In this case, an NDN signal cannot be sent to this telex user. Recommendation F.201). 5 Validation of the Teletex address by means of a validation call or data base retrieval of the Teletex address (see 6 Validation result (see
46、 3.2.2.4). 7 See Note 5 to Figure 1. 8 EO1 is coded as four ITA2 Combination No. 26 “+ + + +“ in figure shift mode. This EO1 signal needs not to be transferred to the Teletex side. 9 10 Content of IMA is defined in 3.2.2.5. The telex user may maintain connection at this step of the procedure in orde
47、r to obtain an on-line delivery The CF may offer the follow-on message facility at this step (see 3.2.2.8). After the call reattempt procedures have been completed and the message cannot be delivered to the Teletex terminal, acknowledgement (see 3.2.2.7). 11 12 a non-delivery notification (NDN) shou
48、ld be sent to the originating telex customer (see 3.2.2.6). 6 Recommendation U.201 (03/93) ITU-T RECMN*U.ZOL 93 4862593 0594209 24T Teletex address 3.2.2.2 Address input - eetex mnemonic + - 3.2.2.2.1 Single address input format +3 Tdetex amass - Teldectmemonic t G ADD Telexaddress a) Case 1 - If th
49、e telex subscriber has a processable answerback according to Recommendation U.74, minimum address input is: + 9 Optional input + TO90135O-WdO5 Teletex address is the call-numeric string necessary to select the Teletex terminal, i.e. - If there is only one network supporting the Teletex service, the Teletex address is the national Teletex number. - If there is more than one network supporting the Teletex service, the Teletex address includes the DNICCC number according to Recommendation X. 12 I. DNIC or TCC may be separated from the national Teletex numb
