1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU F.72 (I 0196) SERIES F: NON-TELEPHONE TELECOMMUNICATION SERVICES Telegraph service - The international telex service The international telex service - General principles and operational aspects of a store and
2、 fonnrard facility ITU-T Recommendation F.72 (Previously CCITT Recommendation) - - STD-ITU-T RECMN F-72-ENGL L99b 4b259L Ob34084 b19 m ITU-T F-SERIES RECOMMENDATIONS NON-TELEPHONE TELECOMMUNICATION SERVICES TELEGRAPH SERVICE Operating methods for the international public telegram service The gentex
3、network Message switching The international telemessage service F. I-F. 109 F. I-F. 19 F.20-F.29 F.30-F.39 F.40-F.58 )I The international telex service F.59-F.89 Statistics and publications on international telegraph services Scheduled and leased communication services Phototelegraph service Mobile
4、services and multidestination satellite services MOBILE SERVICE TELEMATIC SERVICES Public facsimile service Teletex service Videotex service General provisions for telematic services MESSAGE HANDLING SERVICES DIRECTORY SERVICES DOCUMENT COMMUNICATION Document communication Programming communication
5、interfaces DATA TRANSMISSION SERVICES AUDIOVISUAL SERVICES JSDN SERVICES UNIVERSAL PERSONAL TELECOMMUNICATION HUMAN FACTORS F.90-F.99 F. 1 OO-F. 104 F. 105-F. 109 F. 110-F.159 F.110-F.159 F.160-F.399 F. 160-F. 199 F.200-F.299 F.300-F.349 F.350-F.399 F.400-F.499 F.500-F.549 F.550-F.599 F.550-F.579 F.
6、 5 80-F.599 F.600-F.699 F.700-F.799 F.800-F.849 F.850-F.899 F.900-F.999 For further details, please refer to ITU-T List of Recommendations. STD-ITU-T RECMN F.72-ENGL L77b 48b259L b34085 555 FOREWORD The IT-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecom
7、munication Union (IT). The ITU-T is responsible for studying technical, operating and 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 yea
8、rs, establishes the topics for study by the IT-T Study Groups which, in their turn, 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). IT-T Recommendation F.
9、72 was revised by ITU-T Study Group 1 (1993-1996) and was approved by the WTSC (Geneva, 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 right
10、s 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. Recommendation F.72 (10/96) 1 STD.ITU-T RECMN F.72-ENGL Lb 48b25L Ob34Bb 471 m 1 2 3 4 5 6 7
11、8 9 10 11 12 ii CONTENTS Scope General . Service requirements 3.2 Service signals 3.1 Message identification 3.3 Duration of message storage . 3.4 Maximum message length and duration . 3.5 Store full indication . 3.6 3.7 Input transaction accepted . End of transaction and end of message signal 3.8 M
12、essage security . 3.9 Advice of non-dehveryldelivery . 3.1 O Call records . 3.11 Incomplete message Facilities . 4.1 Single address . 4.2 Multi-address 4.3 Follow-on messages 4.4 Classes of delivery 4.5 Cancellation 4.6 Address correction Quality of Service . 5.1 5.2 Error protection . 5.3 Duration
13、of service 5.4 Number of circuits 5.5 Minimum storage capacity Loss probability in the store and forward procedure Access principles Access procedures 7.1 General 7.2 Access from a telex subscriber 7.3 Service request 7.4 Message input . Contents of the address line 8.1 Address line Abnormal conditi
14、ons during message input . Message status enquiry . 10.1 General procedures . 10.2 Status enquiry information field content . 10.3 The status report 10.4 Status report field content . Delivery procedure . Notification procedures 12.2 Notification delivery procedures . 1 1.7 Procedures for delivery o
15、f messages . 12.1 Types of notification . Recommendation F.72 (10196) Page 1 1 3 3 3 3 3 4 4 5 5 5 5 6 6 6 6 6 6 6 6 7 7 7 7 7 7 7 7 7 8 8 8 8 8 10 10 10 10 10 10 11 11 17 17 17 STD-ITU-T RECMN F.72-ENGL 199b D LiAb259L b34087 328 H Page 13 Delivery retry procedures . 17 13.3 Recorded message from t
16、he called subscriber i7 14 Contents of deliveryhon-delivery notifications . 17 15 Internationally interconnected store and forward units 17 . Recommendation F.72 (10/96) 111 - Recommendation F.72 THE INTERNATIONAL TELEX SERVICE - GENERAL PRINCIPLES AND OPERATIONAL ASPECTS OF A STORE AND FORWARD FACI
17、LITY (Melbourne, 1988; revised Helsinki, I993 and Geneva, 1996) The ITU-T considering (a) international telex service; that telex store and forward is included in Recommendation F.63 as an additional facility within the 0) that telex store and forward facilities have been and are being introduced by
18、 many countries; (c) store and forward facility in another country has been identified; that a requirement for access via the international telex service from an originator in one country to a telex (4 another country via Message Handling Services in accordance with F- and X-Series Recommendations,
19、that a store and forward facility in one country may be interconnected with the store and forward facility in unanimously declares that the general principles and operational aspects described in this Recommendation should be adopted for the provision of store and forward as an additional facility w
20、ithin the international telex service. 1 Scope 1.1 This Recommendation is one of a series which define telex store and forward facilities. The other Recommendations are: Recommendation U.80 - International telex store and forward - Access from a telex subscriber. Recommendation U.81 - International
21、telex store and forward -Delivery to a telex subscriber. 1.2 The service requirements and Quality of Service provisions along with the single address facility and classes of delivery specified in this Recommendation are essential for the store and forward facility. The other facilities are optional
22、and will be provided at the discretion of the Administration operating the Store and Forward Unit (SFU). 2 General 2.1 SFU, thus conversational mode connection between terminals is not provided. Within the store and forward facility, communication between terminals is on a store and forward basis vi
23、a the 2.2 The following two types of configuration have been identified as shown in Figure 1 : a) International store and forward is where a subscriber in Country A accesses the store and forward unit in Country B for the transmission of messages to that country. b) Interconnected store and forward
24、is where the store and forward unit in Country A is connected to the store and forward unit in Country B for the transmission of messages between the two countries. Recommendation F.72 (10/96) 1 Country A Telex originator A Telex network International boundary Addressee I Telex network Country B Tel
25、ex originator A Telex network Addressee Telex I network I -r- u Message delivery b Message deposit a) Case of international store and forward III Message delivery Message handling services Message deposit b Messade transfer F.400-, X.400-Series 4 b TO1 03220-931d01 b) Case of interconnected store an
26、d forward Figure 1F.72 - General model for the deployment of SFUs 2.3 procedures can be used for international traffic from a national SFU. Whilst the Recommendation addresses international and interconnected store and forward, the delivery 2.4 Limitations of access to a store and forward facility 2
27、.4.1 Administrations concerned. The configurations identified in 2.2 will be provided on the basis of bilateral agreements between the 2.4.2 An Administration operating an SFU should be responsible for the barring of intemational access from unauthorized users and for barring unauthorized types of c
28、all such as transit calls to specific countries. The method of barring shall be the responsibility of the Administration operating the SFU and is beyond the scope of this Recommendation. 2.4.3 countries. It may also be necessary for Administrations to make provision to selectively block access to SF
29、Us in other 2 Recommendation F.72 (10/96) 3 Service requirements 3.1 Message identification The SFU will provide to the, subscriber a unique message reference readily identifiable for every message, comprising: a) the date and time of message input as provided to the originating telex subscriber in
30、accordance with Recommendation U.80; and b) the message reference number as allocated and provided to the originating telex subscriber at the time of input of the message. 3.2 Service signals 3.2.1 Service signals received by the SFU All standardized telex service signals (see Recommendation F.60 fo
31、r a list of code expressions and appropriate U-Series Recommendations for their format) must be recognized by the SFU. The retry procedure will be according to the principles of Recommendation U.40. It is desirable that the SFU attempt to interpret non-standard service signal and continue with the a
32、ppropriate procedure. If the SFU is unable to interpret a non-standard service signal, the SFU should give a non-delivery notification to the calling subscriber and repeat the service signal in the format received. 3.2.2 Code expressions sent by the SFU The following code expressions may be generate
33、d by the SFU: ADD BMC Please input your international telex number No end of message or end of transmission received, therefore message cancelled IAB IMA ITD ITR LDE occ REJ TMA Invalid answerback from destination (only sent as part of a non-delivery notification) Input message acknowledgement Input
34、 transaction accepted for delivery Input transactions rejected Maximum acceptable message length or duration has been exceeded Store full, SFU unavailable Address rejected Maximum number of addresses exceeded 3.3 Duration of message storage The retry procedure applied by the SFU should be in accorda
35、nce with the principles of Recommendation U.40. However, the period for which the SFU should retain responsibility for the message should not exceed 24 hours from time of input. If delivery has not been effected, the procedure as in 3.9 should apply. 3.4 Maximum message length and duration 3.4.1 All
36、 SFUs should have sufficient capacity to accept at least 24000 characters per single message. Exceptionally, some SFUs may set this limit at 12 O00 characters or even lower. Subscribers should therefore be advised by their Administrations as to the maximum message length accepted by those SFUs to wh
37、ich they have access. 3.4.2 by the Administrations operating the SFUs. In the case of interconnected SFUs, the maximum acceptable message length of the SFUs should be agreed to 3.4.3 The maximum input duration for a single transaction should be two hours. Recommendation F.72 (10/96) 3 STD-ITU-T RECM
38、N F-72-ENGL L99b = 48b259L 0b34091 859 Sequence NNNN NNNNACK + 3.4.4 If the maximum acceptable message length or duration is reached, the sender should be advised by sending to him the service code LDE. Prior to sending the service code LDE, an attempt should be made to stop his transmission by send
39、ing the letter T, repeatedly in accordance with Recommendation S.4. Mnemonic EOM EOM(ACK) EOT 3.4.5 Transaction signal (EOT) and proceed in accordance with 3.6. After sending the service code LDE, the SFU will wait for the End of Message signal (EOM) or End of Used to request Input Message Acknowled
40、gement (IMA) of previously deposited messages, to separate messages, and to request a follow-on call. End of transaction signal, used to indicate to the SFU that the transaction has been completed and also to request message reference information for previously submitted messages not already acknowl
41、edged. 3.5 Store full indication As for EOM, except that messages already acknowledged will be delivered whatever the subsequent action by either the subscriber or the SFU. Provides message reference information and initiates clearing. Messages should cease to be accepted when the levei of store cap
42、acity is reduced to a predetermined state to ensure that any messages in the process of being transmitted to the unit can be accepted in their entirety, bearing in mind the provisions of 3.4. The unit will return the service code OCC in response to attempts to access the unit for message input. 3.6
43、End of transaction and end of message signal 3.6.1 At the end of each transaction, an End of Transaction (EOT) signal is required. This signal is +. However, for follow-on messages, an End of Message (EOM) signal is required at the end of each individual message. The functions of these signals are d
44、escribed in Table 1. Table UF.72 - Functions of end of message and end of transaction signals I Action by SFU I Function Used to separate different messages (end of message) deposited in the SFU during the same transaction for delivery to different addresses or groups of addresses. 1) Enables follow
45、-on calls to be provided by the SFU. 2) Will result in force clearing by the SFU and cancellation of the message(s) if not followed by either an address or the EOT signal. 3.6.2 expression GA should be sent to the subscriber. If there is a stop in transmission for 30 seconds without receipt of eithe
46、r an EOM or EOT signal, the code 3.6.3 shall initiate the clear down procedure. If the EOMEOT signal is not received, or transmission does not resume within a further 30 seconds, the SFU 3.6.4 The incomplete message should either be cancelled or, optionally, sent to an operator assistance position.
47、3.6.5 EOM/EOT signal has been received by sending the code expression BMC. If the message is to be cancelled before clearing the connection, the SFU should inform the subscriber that no 3.6.6 processed as in 3.6.4. In the event of clear down by the caller without an EOM or EOT signal, the incomplete
48、 message(s) will be 4 Recommendation F.72 (10/96) STD-ITU-T RECMN F-72-ENGL L97b H 4862571 Ob34092 795 3.7 Input transaction accepted On receipt of an EOT signal, the SFU should send an input transaction accepted for delivery signal (ITD) notifying the subscriber that the message(s) hashave been acc
49、epted and that delivery will be attempted. Delivery should be attempted even if the call is cleared before the ITD is sent. The ITD should be followed by the message reference(s) and, if applicable, number of messages. 3.8 Message security 3.8.1 Message acceptance 3.8.1.1 for other destinations should be refused with code expression NA for the reason of non-delivery. The SFU should only accept messages for delivery to destination addresses served by that SFU. Any messages 3.8.1.2 been received at call set-up in accordance with Recommendations U.74 and
