1、ITU-T RECMN*U-200 93 m 4862.591 0588773 648 m INTERNATIONAL TELECOMMUNICATION UN ION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU TELEGRAPH SWITCHING INTERNATIONAL TELEX SERVICE u.200 (03/93) THE INTERNATIONAL TELEX SERVICE - GENERAL TECHNICAL REQUIREMENTS FOR INTERWORKING ITU-T Recommendat
2、ion U.200 (Previously “CCIlT Recommendation”) ITU-T RECMN*U.200 93 = 4862571 0588772 584 = 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 ques
3、tions 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 Recomm
4、endations on these topics. ITU-T Recommendation U.200 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 to exist as of 28
5、 February 1993. In its place, the IT Telecommunication Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRE3 have been replaced by the Radiocommunication Sector. In order not to delay publication of this Recommendation, no change has
6、 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 a
7、nd 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 photocopying
8、 and microfilm, without permission in writing from the ITU. ITU-T RECMN*U=ZOO 93 m 4862593 0588773 410 m CONTENTS Definitions . Abbreviations 1 2 3 4 5 6 7 8 9 10 11 12 Scope General interworking scenario . Tasks of the IWF Access to an IWF from the telex network 4.1 One-stage selection . 4.1.1 Proc
9、edure 4.2 Two-stage selection 4.3 Notes to Table 2 and Table 3a 4.3.1 Note 1 4.3.2 Note 2 4.4 Use of a Status Enquiry Function . Text transfer . 5.1 Description of text transfer modes 5.1.1 Real time . 5.1.2 Store-and-forward 5.1.3 Store-and-retrieve . 5.2 Text transfer in a packet switched environm
10、ent . 5.3 End of text transfer . Conformance to the international telex service Access to telex from other networks/services 7.1 Call Set-up . 7.2 Text Transfer Phase 7.2.1 Real time . 7.2.2 Store-and-forward . Handling of recall address 7.3.1 One-stage IWF 7.3 7.3.2 Two-stage IWF . Clearing Notific
11、ations, Journals, Advise of Status . Ineffective call attempts . Reaction to abnormal conditions Interworking by the use of a telex store-and-forward unit . Annex A . General scheme for access protocols Recomrnenda tion U.200 (03/93) Page 1 1 2 3 4 5 5 7 7 10 10 10 10 11 11 11 11 11 11 11 11 13 13 1
12、3 13 13 13 13 14 14 14 15 15 15 16 1 ITU-T RECMN5U.200 73 48b2591 0588774 357 Recommendation U.200 THE INTERNATIONAL TELEX SERVICE - GENERAL TECHNICAL REQUIREMENTS FOR INTERWORKING (Helsinki, 1993) Definitions non-telex terminal: Within this Recommendation the tem “non-telex terminai” is used for an
13、y terminal which does not belong to the international telex service or is not connected to the international telex service directly, but can be accessed via the international telex service. Abbreviations ACK ADD AU BK BMC BT CF COM DTE EO1 EOT FAXIWF GA IMA ISDN ITD ITL IWF MOB MOM MSSF ODA O/R PDN
14、PSPDN PSTN PTLXAU SEF SFU TAED TPIWF VTXCF Request for positive delivery notification Please input your international telex number Access UnitDD3 I cut off No end of message or end of transmission received, therefore message cancelled End of addres-egin text signal Conversion Facility Connected PAD
15、service signal (see Recommendation X.28)I Data Terminal Equipment End of InputDD4 End of TransactionDDS Teleflacsimile Interworking FunctionDD6 You may transmitMay I transmit? Input Message AcknowledgementDD7 Integrated Services Digital Network Input Transaction accepted for Delivery I Transmit Late
16、r Interworking FunctionDD8 Mobile Waitlwaiting Maritime Satellite Store-and-Forward UnitDD9 On-line Delivery AcknowledgementDDlO Originator/RecipientDD 1 i Positive Delivery NotificationDD12 Packet Switched Public Data Network Public Switched Telephone Network Public Telex Access UnitDD13 Status Enq
17、uiry FunctionDD14 Store-and-Forward Unit Telex Automatic Emitting DeviceDD15 Telex Packet Interworking FunctionDD 161 TelexNideotex Conversion FacilityDD171 Recommendation U.200 (03/93) 1 ITU-T RECMN*U.200 93 = 4862573 0588775 293 u.200 1 Scope 1.1 Interworking as defined in this Recommendation is c
18、onsidered: This Recommendation defines the technical interworking principles with the international telex service. i) between the international telex service and other CCITT defined services; or ii) between terminals of the international telex service and non-telex terminals connected to other netwo
19、rks; or iii) between two dissimilar networks providing the international telex service. Interworking between telex signalling Types A, B, C and D is described in Recommendation U. 15. 1.2 The objectives of this Recommendation are: - to specify in a generic form the access protocol from the telex net
20、work to the interworking function and vice-versa; to specify in a generic form the different text transfer modes, applicable to interworking; to indicate the applicability of user and exchange facilities in the case of interworking; to indicate the degree of conformance with the basic characteristic
21、s of the international telex service resulting from the interworking scenario; to define a preferred access protocol for new interworking scenarios; to give an overview of all relevant interworking Recommendations. - - - - - 1.3 The rapid evolution of data transmission and Telematic services has res
22、ulted in a large number of international standards in this field. The increasing complexity of the totality of these standards creates a need to standardize interworking procedures with the international telex service. The telex service may be provided in the future by different types of public netw
23、orks. As a result there may be a demand to interconnect these networks in order for a telex terminal on one network to communicate in a standardized way with a telex terminal on the same network, or on another network, or with a non-telex terminal of a network of another type. This Recommendation is
24、 the first of a family of interworking Recommendations. Figure 1 and Table 1 give a summary of the relevant interworking Recommendations. TU( TrX TU( TM TU( TU( TM TU( TU( IPMS VTX FAX Intex DE ISDN MOB I. To900790-911do1 NOTE - U.208 inmusataone-stage. FIGURE 1AJ.200 Organization of telex interwork
25、ing Recommendations 2 Recommendation U.200 (03/93) ITU-T RECMN*U*200 93 W 48b259L 0588776 12T TABLE 1AJ.200 Family of interworking Recommendations relation to the international telex service Title of the technical Recommendation he international telex service - General technical requirements ror int
26、erworking interworking between the Teletex service and the international telex service Technical requirements to be met in providing the international telex service within an Integrated Services Digital Network Technical requirements to be met when providing real-time bothway communications between
27、terminals of the international telex service and data terminal equipments on a PSPDN or via the PSTN Interworking between the international telex service and the public interpersonal messaging service Store-and-retrieve facility for the delivery of messages from a terminal of the international telex
28、 service to a data terminal equipment which connects to a packet-switched public data network over the public switched telephone network Technical requirements for interworking between the international telex service and the Videotex service Technical requirements to be met for the transfer of messa
29、ges between terminals of the intemational telex service and Group 3 facsimile terminals connected to the PSTN The international telex service - Interworking with the INMARSAT C system using one-stage selection Intex service - Network requirements to effect interworking with the intemational telex se
30、rviceb) The international telex service - Technical requirements for a Status Enquiry Function in an interworking scenario Intex terminals - Requirements to effect interworking with the international telex serviceb) a) As defined in 1.1. b) ntex - Provisional name. Tehcnical Rec. u.200 u.201 u.202 U
31、.203 u.204 U.205 U.206 U.207 U.208 u.210 u.220 s.34 Service RW. F. 80 F.8 i F.20 1 F.59F.60 F.83 F. 84lF.42 1 F.83 F.86 F.87 F. i 27 F.82 F. 89 F.82 Interworking Typea) I, II, III I III II I II I I II I I, II I 2 General interworking scenario The operational procedures and full range of facilities a
32、vailable for each interworking case are described in Recommendation F.80 and other associated F-Series Recommendations. The interworking capability shall be established by the provision of an Interworking Function (IWF). The method of implementation of an IWF in any physical unit is a national matte
33、r. To avoid accounting problems on international interworking relations, the point of interworking between the two networks should always be in the country where the terminal connected to the other network and/or participating on the other service is located. Therefore the international connection s
34、hould be via the telex network as shown in Figure 2. However, there are exceptions defined in the relevant F-Series Recommendations (e.g. Recommendation F.201). Recommendation U.200 (03/93) 3 ITU-T RECMN*U*200 93 4862593 0588777 066 I International Telex SeMc! i i i I i i I - - Telex Telex Telex IWF
35、 Terminal Network I Netwwk (Note 1) I I I I I : Country B Country A Other Network or SeMce NOTES 1 Within this Recommendation the term “interworking Function” or “IWF includes the following functions used in other U.200-Series Recommendations: - CF (U.201) - AU (U.202) - MrF (U.202) -TPIWF (U.203) -
36、PTW(AU (U.204) - VTXCF (U.206) - FAXIWF (U.207) - MSSFU (U.208) 2 If the destination country does not provide the IWF between the telex network and the network to which the requested terminal is connected, the WF may be provided by the originating network. FIGURE uU.200 Basic made4 for international
37、 interworking between the international telex service and other networks and services 3 Tasks of the IWF Depending on the application the IWF is responsible for the following tasks: - - - mapping of the signalling events; receipt of characters from the telex network, and conversion for forward trans
38、mission; receipt of characters of the other network, and conversion of them to start-stop characters for forward transmission to the telex network; code conversion in accordance to the relevant CCITT Recommendations; alignment of the “shift” conditions on either side of the IWF; handling of the WRU
39、signal and answerback codes; mapping of telex service signals; handling of characters received on the backward signalling path while forward transmission is in progress; mapping of clearing signals from either network; relevant procedures on the other networkkervice; packetizing - when required - in
40、 accordance with the prescribed conditions. - - - - - - - - 4 Recommendation U.200 (03D3) ITU-T RECMN*U-200 93 48b259L 0588778 TT2 4 Access to an IWF from the telex network Two basic procedures should be provided by the IWF to allow access from the telex subscriber: a) b) interactive operation, prim
41、arily to cater for manually calling telex terminals; in this procedure the Interworking Function may return prompt signals; non-interactive operation, to cater for access from Telex Automatic Emitting Devices (TAEDs). In this procedure prompt signals must not be returned. The following methods of ac
42、cessing an IWF from the telex side may be employed: i) interworking with one-stage selection; ii) interworking with two-stage selection. Accessing the IWF by two-stage selection method is necessary in the following cases: - the called address does not form a part of the telex numbering plan, e.g. Re
43、commendations E.163 and X. i 21 (not all cases), OR address; - multi-address calls; - follow-on calls; - - request for positive delivery notification; use of service parameters, e.g. delayed delivery. 4.1 One-stage selection In the one-stage selection procedure the called party will be assigned a te
44、lex number that is part of the national numbering plan. This procedure requires the registration of each non-telex terminal that wants to communicate with telex subscribers and the assignment of a telex number to it. It is the responsibility of the IWF to translate, where neccessary, this assigned n
45、umber to the relevant call number of the requested terminal. Where, however, the destination country has implemented an integrated national numbering plan, then the assigned national number of the non-telex terminal may be used by the calling telex subscriber provided this does not lead to an intern
46、ational telex address consisting of more than 12 digits to allow accommodation within the international telex signalling requirements. Figure 3 shows the elements of the access procedure, Table 2 shows how these elements different interworking scenarios and Annex A shows a general scheme for access
47、protocols. 1) Call I I 2) Cali connect I I I I 3) Called partys answerback I 4) 5) Text transfer I Identification of the calling telex subscriber are implemented in the I 6) Clearing FIGURE 3N.200 Elements of the telex access procedure (one-stage selection) Recommendation U.200 (03/93) 5 ITU-T RECMN
48、*U.200 93 W 48b259L 0588779 939 W 8 r? 3 O r? 3 C O .- Y 2 f c2g Y 8,. E o 6 Recommendation U.200 (03/93) ITU-T RECMNJU.200 93 m 4862573 0588780 b50 m 4.1.1 Procedure The procedures to be used shall generally conform to the provisions of Recommendation F.60. The telex number received by the IWF shal
49、l be verified as being proper to a registered non-telex termini The method of effecting this verification is a national matter. If the verification fails and both the telex network and the IWF are operated by the same administration, the IWF should clear backwards with the service signal NP. If the called party is a non-telex terminal the answerback of the called terminal to be returned to the calling telex subscriber at any stage of the call shall be formatted in accordance with Recommendation F.74. This indicates to the calling telex subscriber that
