ITU-T U 220-1993 International Telex Service - Technical Requirements for a Status Enquiry Function in an Interworking Scenario - Telegraph Switching - International Telex Service .pdf

1、ITU-T RECMN*U.220 33 4862533 0588849 082 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU TELEGRAPH SWITCHING INTERNATIONAL TELEX SERVICE u.220 (03/93) THE INTERNATIONAL TELEX SERVICE - TECHNICAL REQUIREMENTS FOR A STATUS ENQUIRY FUNCTION IN AN INTERWORKING

2、 SCENARIO ITU-T Recommendation U.220 (Previously “CCITT Recommendation”) ITU-T RECMN*U-220 93 W 48b259L 0588850 8T4 W 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

3、, operating 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 ITU-T Study Groups which, in

4、 their turn, produce Recommendations on these topics. ITU-T Recommendation U.220 was prepared 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 CC

5、IT ceased to exist as of 28 February 1993. In its place, the ITU 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 Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector.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 Re

6、commendation, 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 ITU structure. 2 teleco

7、mmunication 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 mechan

8、ical, including photocopying and microfilm, without permission in writing from the ITU. ITU-T RECMN*U-220 93 m 48b2592 0588852 730 m CONTENTS Page 1 Scope 1 2 General principles 1 2.1 Access types 1 2.2 Applicability for a telex subscriber . 1 Types of functions to be provided by the SEF 3 Access pr

9、otocols . 3 Access protocol by use of an access number different from the normal WF number . Access protocol by use of the same access number as the normal IW number 2.3 2 3.1 3.2 3 5 Recommendation U.220 (03/93) 1 ITU-T RECMNtU.220 93 4862591 0588852 677 Recommendation U.220 THE INTERNATIONAL TELEX

10、 SERVICE - TECHNICAL REQUIREMENTS FOR A STATUS ENQUIRY FUNCTION IN AN INTERWORKING SCENARIO (Helsinki, 1993) 1 Scope 1.1 The provisions of this Recommendation are limited to enquiries concerning messages handled by an IWF in accordance with the relevant U-Series Recommendations. Status enquiry in re

11、spect of messages deposited into a telex SFU for delivery to the International Telex Service are handled in accordance with Recommendations F.72, U.80 and U.81. The provisions of this Recommendation should be applied to future implementations and, as far as possible, to existing implementations of I

12、WF and SFU, in the latter case, as an alternative to the provisions of Recommendations F.72, U.80 and U.81 in respect of status enquiry. 1.2 This Recommendation defines: - a Status Enquiry Function (SEF) which will be always associated with an Interworking Function (IWF) or a store-and-forward unit

13、(SFU); the protocols to be applied to enable a subscriber of the International Telex Service to request status information about one or more messages previously deposited; the format of the status information to be provided to a subscriber of the International Telex Service by an SEF in response to

14、a status enquiry. - - 1.3 The service requirements, relevant to a Status Enquiry Function are defined in Recommendation F.89. 2 General principles 2.1 Access types Access to an SEF can be provided in one or both of the following ways: 2.1.1 Function (IWF). By use of an access number, different from

15、the number used for the message deposit in an Interworking For the case that the message was deposited in a one-stage IWF, this type of access can only be applied. The relating protocol is described in 3.1. 2.1.2 By use of the same access number as used for the message deposit in an IWF. The relatin

16、g protocol is described in 3.2. 2.2 Applicability for a telex subscriber 2.2.1 where store-and-forward principles apply for the telex-to-non-telex direction: In an interworking environment, access to an SEF is normally applicable only for these interworking cases - telex-to-Teletex (see Recommendati

17、on U.201); - telex-to-facsimile (see Recommendation U.207); - telex-to-Inmarsat C (see Recommendation U.208). Recommendation U.220 (03/93) 1 ITU-T RECflN*U*220 93 = 486259L 0588853 503 2.2.2 provides information about delivery to the destination subscribers mailbox (or user agent) only: For interwor

18、king cases where store-and-retrieve principles apply in the telex-to-non-telex direction the SEF - telex/DTE (PSTN) (see Recommendation U.205); - telex/IPMS (see Recommendation U.204); - teleflideotex (see Recommendation U.206). Provision of information about delivery to the destination user is for

19、further study, 2.2.3 The provisions in this Recommendation can also be applied in case of a telex store-and-forward unit (SFU) for both, a basic teledtelex environment and a mixed environment where the SFU is used for telex and non-telex destinations. 2.3 Types of functions to be provided by the SEF

20、 2.3.1 Information about single messages (ENQ) The provision of information about a single message is only possible in cases where a message reference information was provided by the IWF at the deposit of the message. This is normally only possible in case of a two-stage IWF. However, where an IMA w

21、as used in case of a one-stage IWF a message reference information is available also in this case. 2.3.2 Journal (JOU) The provision of information in the form of a Journal (information about all messages relevant to the calling telex answerback) is possible in all cases where the answerback of the

22、calling telex subscriber was captured at message deposit. This is always the case in a two-stage IWF and most times in case of a one-stage IWF. 2.3.3 Cancel (CAN) The provision of this function is only allowed for messages, addressed to destinations of certain services, Le. where the definition of t

23、he interworking allows the cancellation of previously deposited messages (see specific F-Series Recommendation, e.g. F.87). 2.4 The SEF shall ensure that information about messages shall be provided only to the originator. The relation between the subscriber and the deposited messages is checked by

24、the IWF on the basis of the information contained in the subscribers answerback in one of the following ways: - the national number and the TNIC, both captured under use of the rules laid down in Recommendation U.74; or - on a character-by-character comparison where the answerback is not processable

25、 in accordance with Recommendation U.74. 2.5 As the SEF needs information (request and message reference information) from the calling telex subscriber, the access protocol is normally interactive and can therefore be used with manual telex terminals only. The access to an SEF for Telex Automatic Em

26、itting Devices (TAEDs) using a non-interactive protocol is for further study. 2.6 message or after successful delivery of an NDN. Normally, information about a message will be deleted in an IWF either after successful delivery of the Where an SEF is also provided in the IWF, information about the st

27、atus of a message shall be available for enquiry at least 72 hours after acceptance. 2.7 character. Any input into the SEF by the calling telex subscriber shall be on a single line and shall be terminated by a “+“ 2.8 subscriber. Any response provided by the SEF should start within three seconds aft

28、er a request by the calling telex 2 Recommendation U.220 (03/93) ITU-T RECMN*Um220 93 = 4862571 0588854 44T = 3 Access protocols 3.1 The access procedure is shown in Figure 1 and the appending notes. Access protocol by use of an access number different from the normal IW number Nmai telex procedures

29、 1 SEF answerback (Note li I WRU signal (Note 2) Answerback (Note 2) D Request (Note 3) D GA? (Note 4) +- Request (Note 4) + Service provision (Note 5) GA (Note 6) -_- 7- Clearing (Note 6) I S E F FIGURE 1AJ.220 Access to an SEF using a separate access number 3.1.1 Coding of the SEF answerback shall

30、 be in accordance with Recommendation F.60 and shall contain the following information: Note 1 to Figure 1 “Figs”, “CR, “LF, National Number, “Lttrs”, “SP, ENQ, “SP”, O O means the TNIC as in Recommendation F.69, e.g. “F for FRANCE. Example: 666001 enq f 3.1.2 A WRU signal shall be transmitted in ac

31、cordance with Recommendation S.23. On the basis of the answerback received (see 2.4), the SEF shall check if the status of one or more messages is stored for the calling subscriber. If no status of a message is stored the SEF shall return “NA” and disconnect. Note 2 to Figure 1 3.1.3 The calling tel

32、ex subscriber shall input his request, consisting of Note 3 to Figure 1 - a service request identifier; - - the message reference information as received at the message deposit; the end of address signal (+). Service request identifier and message reference information shall be separated by a space

33、character. The following service request identifiers may be provided by the calling telex subscriber: ENQ CAN JOU (the SEF shall also accept the complete word ENQUIRY) (the SEF shall also accept the complete word CANCEL) (the SEF shall also accept the complete word JOURNAL) Recommendation U.220 (03/

34、93) ITU-T RECMN*U.220 33 4862533 0588855 386 = In the JOURNAL case a message reference information is not necessary to be provided by the calling telex subscriber. 3.1.4 Examples: ENQ xxxxx+ CANCEL xxxxx+ JOU+ ENQUIRY xxxxx+ EN xxxxx stands for the message reference information, Note 4 to Figure 1 I

35、f the te.;x subscriber does not commence input within five seconds, the SEF sha send a “GA? prompt. In response, the telex subscriber shall provide his request as in 3.1.3. If the telex subscriber does not start within another 15-second period or pauses for 15 seconds, the SEF shall return “NP and c

36、lear the call. If the telex subscriber does provide an invalid service request the SEF shall return the relevant code expression and disconnect. 3.1.5 If the SEF identified a message reference information as relevant to a message (when applicable) belonging to the calling telex subscriber, the SEF w

37、ill, according to the service request identifier, provide the following information. Note 5 to Figure 1 If the SEF could identify a message reference information, to which no message status is available for the caller the text “NO MESSAGE shall be returned followed by a “GA” as in 3.1.6. 3.1.5.1 In

38、case of ENQ, followed by a valid message reference, the status of the message containing: a) message reference information; b) status of the message, either: - “delivered”; or - “not yet delivered”; or - “not delivered”; or - “cancelled”, c) called address; d) e) f, g) answerback or terminal identif

39、ication received (where relevant); number of delivery attempts (if relevant); latest reason for non-delivery (if relevant); datehime of last delivery attempt (optional) “not yet delivered” stands for: - - - message is in transmission phase; and/or message is scheduled for additional delivery attempt

40、s; or first delivery attempt did not commence, “not delivered” means that no further attempt will be made to deliver the message. The content of the message is no longer available. The format of the status provision is a national matter. Where the calling telex subscriber provided an ENQ indicator i

41、n relation to a multi-address message the status of the message should be provided in a Journal form as described in 3.1.5.3. 4 Recommendation U.220 (03/93) ITU-T RECMN*U-220 93 m 4862593 0588856 232 Normal telex proceches IWF answerback (Note 1) 4 WRU (Note 1) 4 Answerback (Note 1) + ADD prompt (No

42、t- 1,5) +-. Telex address (Note 1 I 5) GA (Notes 1,5) Rqet (Note 2) Seruce provision (Note 3) 4 GA (Note 4) 4 Clearing (Note 4) 4 + -_- b 3.1.5.2 In case of CAN, information containing: - message reference information; - - called address: - the words; time of message deposit (may be part of the mess

43、age reference information); - “CANCELLED or - “UNABLE TO CANCEL” in case the message is in transmission; or - “DELIVERED. I w F The format of the information is a national matter. 3.1.5.3 the same information as for a status provision (see 3.1.5.1). In case of JOU+, or ENQ+, a Journal containing for

44、 each message (and address in the case of multi-address) The format of the Journal is a national matter, but shall show the information for one message (or address) on a single line. The order of the information lines shall be as the messages where submitted, the latest being the first. A pause of t

45、hree seconds shall be inserted in the text stream after every five lines of status information to facilitate clearing of the connection by the originating telex subscriber. An example for a Journal can be found in Recommendation U.8 1. 3.1.6 Note 6 to Figure 1 After the information provision the SEF

46、 shall send a “GA” prompt and wait 15 seconds to allow the telex subscriber a new request. If no new request or clearing is detected the SEF shall clear in accordance with Recommendation S.20. 3.2 The access procedure is shown in Figure 2 and the appending Notes. Access protocol by use of the same a

47、ccess number as the normal IWF number FIGURE 2N.220 Access to the SEF using the same access number as the normal IWF number Recommendation U.220 (03/93) ITU-T RECMN*U.220 93 m 48b259L 0588857 159 m 3.2.1 Same procedure as for the normal IWF protocol, as defined in the relevant U-Series Recommendatio

48、n. Note 1 to Figure 2 3.2.2 Instead of the input of the called address, the telex subscriber shall input his request as in 3.1.3. If no message is stored for the calling subscriber the IWF shall react as in 3.1.2. Note 2 to Figure 2 3.2.3 See 3.1.6. Note 3 to Figure 2 3.2.4 See 3.1.7. Note 4 to Figu

49、re 2 Instead of a new service request identifier the telex subscriber may input a new called address as relevant to the MrF. 3.2.5 In accordance with Recommendation U.200, this ADD prompt does not apply to a TPIWF (see Recommendation U.203) and to a VTXCF (see Recommendation U.206). Note 5 to Figure 2 6 Recommendation U.220 (03/93)