InfoMagic Standards 1993 July

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THE DRAWINGS CONTAINED IN THIS RECOMMENDATION HAVE BEEN DONE IN AUTOCAD. Recommendation U.81 INTERNATIONAL TELEX STORE AND FORWARD - DELIVERY TO TELEX (Malaga-Torremolinos, 1984; amended at Melbourne, 1989) The CCITT, considering (a) that telex store and forward units exist and are being introduced increasingly into national networks; (b) that delivery procedures differ significantly between different units; (c) that a standard delivery procedure would be desirable for international working, unanimously declares the view that the international telex delivery procedure described in this Recommendation should be adopted for all future telex store and forward units. 1 Scope 1.1 This Recommendation outlines procedures for the delivery of international telex messages by a store and forward unit (SFU). 1.2 The Recommendation comprises the following: 1.2.1 Message forwarding procedure. 1.2.2 Delivery re-attempt. 1.2.3 Notification procedure. 1.3 The procedures detailed in this Recommendation specify the minimum requirement that should be provided by the telex SFU. 1.4 The procedures should apply to all classes of message delivery. 1.5 The priority and time of message delivery should be the responsibility of the telex SFU that has accepted the input message for delivery. In the case of international interworking between telex SFUs, the priority and time of message delivery may be controlled by the originating or destination SFU, subject to bilateral agreement between the Administrations concerned. 1.6 This Recommendation is one of a series which define telex store and forward services. These Recommendations are: - Recommendation F.72: International telex store and forward - General principles and operational aspects. - Recommendation U.80: International telex store and forward - Access from telex. - Recommendation U.81: International telex store and forward - Delivery to telex. - Recommendation U.82: International telex store and forward - International interconnection of telex store and forward units. Fascicle VII.2 - Rec. U.81 PAGE1 2 Definitions 2.1 The term delivery of messages applies to the forwarding of messages input into a telex SFU by an originating telex subscriber to a destination telex subscriber over an international telex network. 2.2 The term notification applies to the forwarding of an advice of delivery/non-delivery of a message to the originating telex subscriber over an international telex circuit. 3 Telex message forwarding procedures 3.1 The sequence of the message forwarding procedure components are illustrated in Figures 1/U.81 and 2/U.81. 3.2 The components of message forwarding procedures are as follows: 3.2.1 Call set-up Call set-up is the establishment of a connection by an SFU over the telex network up to and including the receipt of the call connect signal. In the event of an unsuccessful call set-up attempt, action shall be taken in accordance with S 5. 3.2.2 Called subscriber answerback validation 3.2.2.1 To ensure security of delivery the answerback of the called subscriber should be compared with the anticipated answerback of the called subscriber, if supplied by the originating telex subscriber. 3.2.2.2 The evaluation procedure is given in Recommendation U.75. 3.2.3 Store and forward unit identification The telex SFU identification shall comprise: - the service code CI, - an indication that the call is from a telex SFU, - the date and time of transmission (optional). 3.2.4 Message identification The telex SFU should transmit to the called subscriber a message identification sequence comprising: a) the message reference as allocated and advised to the originating subscriber at the time of input of the telex message for onward delivery; b) the date and time of message input as issued to the originating telex subscriber in accordance with Recommendation U.80. Figure 1/U.81 - CCITT 57543 Figure 2/U.81 - CCITT 76230 3.2.5 Answerback of originating telex subscriber The telex SFU shall transmit to the called subscriber the answerback of the originating subscriber as received at the time of message input. 3.2.6 Message text 3.2.6.1 The telex SFU should transmit to the called subscriber any message header information together with the stored message in the format in which it was originated by the calling subscriber. 3.2.6.2 The EOM/EOT separators and WRU shall not be transmitted. 3.2.6.3 If any signal is received on the backward path during the message text delivery, transmission of the message text shall be stopped for 2 seconds. If during that time further signals or a clearing condition is received, the call shall be cleared and the message delivery deemed unsuccessful, and action taken in accordance with S 5.4. If no further signals are seen on the backward path during that time, transmission of the message text shall be resumed. 3.2.7 Called subscriber answerback comparison 3.2.7.1 The answerback of the called subscriber shall be taken and compared with that received at the start of message delivery. 3.2.7.2 In the event of a mismatch of answerbacks, the answerback of the called subscriber shall be taken once again, and if there is a match with that received at the start of message delivery, the delivery of the message shall be deemed successful. If there is a second mismatch, the delivery of the message shall be considered as unsuccessful, and further delivery attempts shall be made in accordance with S 5.4. 3.2.8 Answerback of originating telex subscriber The answerback of the originating subscriber, as per S 3.2.5, shall then be sent to the called subscriber. 3.2.9 Call clearing sequence PAGE6 Fascicle VII.2 - Rec. U.81 The SFU should clear the call using normal telex clearing procedures. 4 Notification procedures 4.1 General 4.1.1 The advice of non-delivery shall be provided. It should preferably include the list of addresses rejected at the time of address validation. 4.1.2 The advice of delivery over an international telex circuit may be provided subject to bilateral agreement between the Administrations concerned. 4.1.3 Information concerning delivery/non-delivery of messages should be stored and kept available for enquiries from the originator for a pre-defined period of at least 72 hours. 4.1.4 Notification of message delivery/non-delivery may be on a "per message" or "per address" basis. This Recommendation assumes that notification will be returned on a "per message" basis. The provision of a periodic (e.g. daily) notification or journal shall be considered an acceptable form of notification. For a typical, acceptable journal format see Figure 3/U.81. 4.2 The sequence of notification forwarding procedure components are illustrated in Figures 4/U.81 and 5/U.81. S 421000Z UIT CH CI SFU CH TO: 421000 UIT CH HERE IS YOUR JOURNAL FOR 28 APR 1983 REF CALLED ANSWERBACK TOD DURATION 12345 080271666 71666 HKTEL HX 1005 3.1 12987 051261848 261848 THQPH G 1043 2.1 36365 07222500 KDD TOKYO J22500 1240 1.8 36365 0230652464 TRANS A LSA 1240 1.9 Fascicle VII.2 - Rec. U.81 PAGE1 36365 02105827847 CDN MARCO MTL 2045 1.8 36365 423635 423635 HERTZ CH -ABW CANCELLED 41696 07514899 14899 CWI HQ PS 1633 6.0 89635 090522222 -ABS PENDING 89777 023232323 232323 RCAEX UR 1731 1.6 89900 02105566412 -DER CANCELLED PAGE6 Fascicle VII.2 - Rec. U.81 --------- TOTAL MINS 18.3 TOD 1983 04 29 0401 SFU CH S 421000Z UIT CH FIGURE 3/U.81 Typical journal format Figure 4/U.81 - CCITT 57552 Figure 5/U.81 - CCITT 76240 4.3 The components of notification forwarding procedure are as follows: 4.3.1 Call set-up The call set-up should be in accordance with S 3.2.1. 4.3.2 Originating subscriber answerback validation 4.3.2.1 To ensure security of delivery of the notification, the answerback of the originating telex subscriber is taken and compared with the answerback taken from the subscriber at the time of message input. 4.3.2.2 The evaluation procedure is given in Recommendation U.75. 4.3.3 Store and forward unit answerback The answerback of the telex SFU shall be transmitted to the called subscriber. 4.3.4 Store and forward unit identification The telex SFU identification shall be transmitted as per S 3.2.3. 4.3.5 Message identification The telex SFU shall transmit to the called subscriber the message identification sequence issued at the time of input of the message. The format of the message identification should be in accordance with S 3.2.4. 4.3.6 Notification message The notification advice may comprise for each applicable address of a single or multi-address message the following: (See Figure 6/U.81 for example of suggested format.) Example of Delivery Advice 5519751 19751 MIPEN DK Address - Expected A/B DELIVERED Fascicle VII.2 - Rec. U.81 PAGE1 19751 MIPEN DK Advice - Received A/B 18:00 01M 20S Time of Delivery - Duration Example of Non-Delivery 5519751 19751 MIPEN DK Address - Expected A/B NOT DELIVERED Advice - Received A/B (See Note) OCC 4 Reason - No. of Attempts. Note - Only used if incorrect answerback is reason for non-delivery. FIGURE 6/U.81 4.3.6.1 Non-delivery advice - selection information (telex address) - expected answerback (as provided at message input) - notification, i.e. "NOT DELIVERED" - received answerback (if applicable) - reason for non-delivery - number of attempts. 4.3.6.2 Delivery advice - selection information (telex address) - expected answerback (as provided at message input) - notification, i.e. "DELIVERED" PAGE6 Fascicle VII.2 - Rec. U.81 - received answerback - date and time of delivery - duration of call. 4.3.7 Called subscriber answerback validation 4.3.7.1 Answerback comparison of the called subscriber shall be in accordance with S 3.2.7. 4.3.8 Telex SFU answerback The answerback of the SFU shall be transmitted to the called subscriber. 4.3.9 Call clear The calling telex SFU should clear the call using normal telex procedures. 5 Delivery re-attempt procedures 5.1. The principles of Recommendation U.40 shall be applied for all delivery/notification re-attempt requirements. 5.2 If the service signal RDI or NCH is received during call set-up more than once in any one message delivery/notification attempt cycle, the message shall be considered undeliverable. 5.3 Recorded message from called subscriber 5.3.1 If the recorded message is followed by clear, the message shall be considered undeliverable. 5.3.2 Action to be taken by the telex SFU if the recorded message is not followed by clear, needs further study. 5.4 In the failure of an established connection per cases mentioned in S 3.2.6.3 or 3.2.7.2 above, one further attempt to deliver the message may be made after an interval of at least 3 minutes; in this case the message text shall be preceded by POSSIBLE DUPLICATE MESSAGE. 5.5 The action to be taken when a notification cannot be delivered should be the responsibility of the Administration offering the telex SFU service and is a national matter. Fascicle VII.2 - Rec. U.81 PAGE1