1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU U.208 (I 0/96) SERIES U: TELEGRAPH SWITCHING The international telex service The international telex service - Interworking with the INMARSAT C system using one-stage selection ITU-T Recommendation U.208 (Pre
2、viously CCITT Recommendation) I STD-ITU-T RECMN U-ZOA-ENGL L97b 48b2571 Ob3b770 O73 ITU-T U-SERIES RECOMMENDATIONS TELEGRAPH SWITCHING u. 1-u. 10 Specific signalling schemes and interworking between signalling systems U.11-U.19 Signalling over radio and multiplexed channels U.20-U.29 Gentex signalli
3、ng U.30-U.39 Particular signalling facilities U.40-US9 Radiotelex interworking U.60-U.69 Intenvorking between new information services and telex U.70-U.79 Telex store and forward U.80-U.99 Intex service U.100-U.139 Definitions U.140-U.199 The international U.200-U.299 General - For further details,
4、please refer to ITU-T List of Recommendations. STD-ITU-T RECMN U.208-ENGL L99b W 48b259L Ob3b77L TOT W FOREWORD The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The ITU-T is responsible for studying technical, operating and
5、 tariff questions and issuing Recommen- dations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn,
6、produce Recommendations on these topics. The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993). ITU-T Recommendation U.208 was revised by ITU-T Study Group 1 (1993-1996) and was approved by the WTSC (Ge
7、neva, 9- 18 October 1996). NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. O ITU 1997 All rights reserved. No part of this publication may be reproduced or utilized in any form
8、 or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the TU. Recommendation U.208 (10/96) 1 8 9 10 11 CONTENTS Introduction Scope Methods of interworking Access procedures from the international telex service 4.1 Call establishment . 4.
9、2 Determination of the calling telex address Message deposit Clearing Reaction of MSSFU to abnormal conditions during message input . Receipt of non-processable answerback . Pause during input of message text . 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 7.10 Receipt of WRU signal during text input Receipt
10、of national variants of telex characters (Combinations 6, 7, 8 in figures case) . Receipt of ITA2 combination 10 in figures case (Bell signal) Lack of storage capacity during message input Clear by the telex subscriber without the EOT signal . Receipt of characters after the EOT signal . Receipt of
11、clear signal after the EOT signal but before the ITD sequence . Service provided by the INMARSAT C system unavailable Message delivery Delivery notifications . 9.1 Non-delivery notification Calls from MES to a subscriber of the international telex service . MES-to-MES calls utilizing the internation
12、al telex service . Page 1 1 2 2 3 4 4 4 5 5 5 5 5 6 6 6 6 6 6 6 6 6 8 8 11 Recommendation U.208 (1 0/96) Recommendation U.208 THE INTERNATIONAL TELEX SERVICE - INTERWORKING WITH THE INMARSAT C SYSTEM USING ONE-STAGE SELECTION (Helsinki, 1993; revised in Geneva, 1996) 1 Introduction 1.1 With the esta
13、blishment of the INMARSAT C system, there are benefits to be obtained if a standardized procedure is developed which will enable subscribers of the international telex service to send messages to Mobile Earth Stations (MES) participating in that system. 1.2 This Recommendation is one of a set of rel
14、ated Recommendations dealing with this subject, as follows: - - - CCITT Recommendation F.60 (1 992), Operational provisions for the international telex service. CCITT Recommendation F.68 (1 988), Establishment of the automatic intercontinental telex network. ITU-T Recommendation F.69 (1 994), The in
15、ternational telex service - Service and operational provisions of telex destination codes and telex network identification codes. - ITU-T Recommendation F.72 (1996), The international telex service - General principles and operational aspects of a store and forward facility. CCITT Recommendation F.7
16、4 (1 992), Intermediate storage devices accessedfiom the international telex service using single stage selection - answerback format. - - CCITT Recommendation F.120 (1988), Ship station identflcation for VHF/UHF and maritime mob ile-satellite services. ITU-T Recommendation F.125 (1993), Numbering p
17、lan for access to the mobile-satellite services of 1NMARSATfiom the international telex service. - ITU-T Recommendation F. 127 (1996), Operational procedures for interworking between the - international telex service and the service oflered by the INMARSAT C system. CCITT Recommendation F. 130 (1988
18、), Maritime answer-back codes. CCITT Recommendation F. 13 1 (i 988), Radiotelex service codes. CCITT Recommendation U.60 (1984), General requirements to be met in interfacing the international telex network with maritime satellite systems. TU-T Recommendation U.61 (1 993), Detailed requirements to b
19、e met in interfacing the international telex network with maritime satellite systems. - - - - 1.3 contained in the referenced F. 120-Series Recommendations. The definitions of the specific terms used in this Recommendation in relation to the mobile-satellite service are 2 Scope 2.1 The outline descr
20、iption of the INMARSAT C system and the services it may support is contained in Supplement No. 3 to Fascicle 11.4 of the Blue Book (Melbourne, 1988). It is a feature of the service offered by the INMARSAT C system that access to and from the international telex service is to be supported by the serv
21、ice provider, the originating telex subscriber using either one- or two-stage selection depending on the particular MSSFU implementation. 2.2 This Recommendation limits its application to one-stage access from the originating telex subscriber. Access using a two-stage selection procedure shall be in
22、 accordance with Recommendations F.72 and U.80. Administrations may provide either or both modes of operation. 2.3 boundaries on a bilateral basis. Access to the INMARSAT C system may be provided via the international telex network across international Recommendation U.208 (1096) 1 3 Methods of inte
23、nvorking 3.1 The characteristics of the INMARSAT C system are such that messages are forwarded on a store-and-forward basis throughout the system when intenvorking with the international telex service. Thus, conversational telex calls are not supported. 3.2 Interworking with the international telex
24、service is effected by the use of a Mobile Satellite Store-and-Forward Unit (MSSFU) which is the functional interface between the international telex service and the INMARSAT C system. It provides the following functions: intenvorking between the signalling systems used in the mobile satellite messa
25、ge transmission system and the international telex service; intenvorking between the signalling systems used in the maritime satellite message transmission system and the public telex network; routing and call control for calls between a subscriber of the international telex service and a MES; messa
26、ge transfer on a store-and-forward basis between a subscriber of the international telex service and a MES; charging within the INMARSAT system. - - - - - 3.3 The general model for intenvorking between the international telex service and the INMARSAT C system shall therefore be as shown in Figure 1
27、where the international telex service stops at the boundary with the MSSFU. The provisions of this Recommendation relate to the events which take place across that boundary. Satellite - international telex INMARSAT i ni e International network c system Telex s, U.208 Mobile earth station - -. ,/ - -
28、 -. terminal International telex service I. LI T0900820-91 /do1 Figure UU.208 -General model for interworking between the international telex service and the INMARSAT C system 4 Access procedures from the international telex service The MES will be addressed by an originating telex subscriber using
29、the numbering sequence (excluding any prefix) 58S4X1 _-_ Xg, where: 58s is the telex destination code in accordance with Recommendation F.69 (S = 1-4) 4 is the T-digit in accordance with Recommendation F.125, or end of selection signal XI - Xg are part of the MES identity in accordance with Recommen
30、dation F. 125 Figure 2 shows the recommended access procedures in the case of an originating telex subscriber operating in either interactive or non-interactive mode. Access from a telex SFU to an MSSFU shall be in accordance with Recommendation U.8 1. 2 Recommendation U.208 (10/96) Normal telex pro
31、cedures Call Call connect WRU MES NB WRU Telex A/B CI t -_-_ t I; International telex network MSSFU (Note 1) (Note 2) 4 Clear INMARSAT C system (Note 5) EOT (+) NOTE 1 - These procedures are a national matter. NOTE 2 -See 4.2.1. NOTE 3 -The ADD prompt is only sent if the return telex address cannot
32、be determined from the received telex answerback (see 4.2). The calling telex address may be preceded by a CI to iade an automatic terminal. The CI may precede the calling telex address as voluntarily submitted by the caller without any MSSFU generated prompt, as follows: a) CI ADD 50032266 b) ADD (
33、from MSSFU, see 4.2.3) CI 50032266 or NOTE 4 - EOTITD procedure, see 6.3. NOTE 5 -See 6.5. Figure 2N.208 -Call Set-up from the international telex service to an (case of manual terminal or 4.1 Call establishment 4.1.1 The originating telex subscriber will select the MES using normal telex procedures
34、. 4.1.2 matter. The procedures for call establishment between the terminating telex network and the MSSFU are a national 4.1.3 The selection information received by the MSSFU from the telex network will be verified by the MSSFU as being proper to an MES currently logged into the satellite region cov
35、ered by it. The method of effecting this verification is not the subject of international standardization. If the verification fails, the call attempt shall be cleared backwards by the MSSFU with the appropriate service signal in accordance with Recommendation F. 13 1. 4.1.4 normal telex signalling
36、procedures. If the result is positive, the MSSFU shall return the call connect signal to the originating telex subscriber using Recommendation U.208 (1 0/96) 3 4.1.5 The MES answerback returned by the MSSFU shall conform to Recommendation F.74. f 4.1.6 commencing the procedure with non-interactive s
37、ervice request (CI). if the call originates from a telex automatic emitting device, the calling telex subscriber should indicate this by F.69 code National telex number +r+= 4.1.7 international telex service, the delivery procedure described in Recommendation U.8 1 shall apply. Where the call to the
38、 MSSFU has been initiated by a telex SFU operating on behalf of a subscriber of the 4.2 Determination of the calling telex address 4.2.1 originating telex subscriber in accordance with Recommendation S.23. 4.2.2 the rules laid down in Recommendation U.74. Following the transmission of the MES answer
39、back, the MSSFU shall capture the answerback of the The MSSFU shall determine the calling telex address from the received telex answerback in accordance with 4.2.3 Otherwise, the MSSFU shall wait three seconds from the end of the calling telex answerback to enable the telex subscriber to input the c
40、alling telex address. At the end of this period and if the calling telex address cannot be determined from the received telex answerback, the MSSFU shall return the prompt signal ADD. 4.2.4 If the calling telex address is not received within 15 seconds of the ADD prompt, another prompt signal shall
41、be returned. if another 15 seconds elapse without the receipt of the calling telex address, the connection shall be cleared by the MSSFU. However, the call may be accepted by the MSSFU, and the GA prompt returned, where, in the event of non-delivery of an accepted message, alternative arrangements a
42、re in place to provide a non-delivery notification message to the originating telex subscriber, for example, spill out to an assistance position. 4.2.5 The calling telex address shall be input by the telex subscriber in the following format: The calling telex address may optionally be preceded by AD
43、D. 4.2.6 of the calling telex address. The GA prompt shall be sent by the MSSFU if text input has not commenced within five seconds of the receipt 5 Message deposit 5.1 Message input by the originating telex subscriber may commence immediately following: a) b) c) receipt of GA prompt. forwarding of
44、processable telex answerback; or input of telex address; or 5.2 abnormal conditions encountered during message deposit shall be handled in accordance with clause 7. 5.3 telex subscriber. The provisions of Recommendation F.60 regarding message length should be applied in principle. Any The MSSFU shal
45、l be transparent to the receipt of the End-Of-Message signal (N”N) from the originating 6 Clearing 6.1 signal, four times combination 26 in figures case (+). The preferred method of clearing to be applied by the originating telex subscriber is by the use of the EOT 6.2 Clearing without EOT will be t
46、reated as an abnormal condition and handled in accordance with clause 7 4 Recommendation U.208 (10/96) 6.3 The reaction of the MSSFU to receipt of the EOT sequence shall be as follows: a) If the call originated from a manual terminal, the MSSFU shall monitor for the receipt of a WR signai for a maxi
47、mum of two seconds. If a WRU signal is received, the MSSFU shall return the answerback of the MES, followed immediately by the ITD sequence on a separate line. If a WRU sequence is not received within the two-second period, the MSSFU shall return the ITD sequence. If the call originated from an auto
48、matic terminal, the MSSFU shall return the ITD sequence as soon as possible. The ITD sequence and associated message reference information must be returned by the MSSFU within a maximum of five seconds from receipt of the EOT signal. b) c) 6.4 The ITD signal should be followed by the date and time a
49、nd message reference number, as follows: ITD YY-MM-DD/HH-MM Xn x , -_- where XI -_-_ Xn is a message reference assigned by the MSSFU. It should be noted that, as the originating telex subscriber may not be aware of the location of the MSSFU handling his call, the time stamp provided may be different from the local time of the originating telex subscriber. The use of Universal Coordinated Time, in accordance with Recommendation B. 1 1 is therefore preferred. 6.5 to allow the originating telex subscriber clea
