THE DRAWINGS CONTAINED IN THIS RECOMMENDATION HAVE BEEN DONE IN AUTOCAD.
         Recommendation U.74
             EXTRACTION OF TELEX SELECTION INFORMATION FROM A CALLING TELEX 
                                      ANSWERBACK
                      (Malaga-Torremolinos, 1984; amended at Melbourne, 1988)
               The CCITT,
         considering
               (a) that there is a need for automatic  address  extraction  from  a  telex
         answerback (e.g. access to a telex-Teletex conversion facility (CF) or an SFU);
               (b) that Recommendation F.60 defines a preferred structure  for  the  telex
         answerback;
               (c) that different forms of answerbacks exist;
               (d) that Recommendation F.60 bis defines a structure for a telex answerback
         associated with an intermediate document storage device,
         unanimously declares
               that  answerbacks  are  considered  "technically  processable"  (i.e.,  the
         answerback can be interpreted  unambiguously  to  determine  the  F.69  code  and
         national  call  number)  if  they  contain  the   minimum   fields   defined   in
         Recommendation F.60, separated by detectable delimiters, with allowance made  for
         the following additions:
               -   F.60 fields may or may not be in the preferred order;
               -   the Telex Network Identification Code (TNIC) should  be  preceded  and
                  succeeded by detectable delimiters:
                  i)  preceding delimiters are national call number and space,
                  ii) succeeding delimiters are national call number,  space  or  end  of
                      answerback (end of answerback means no more printable characters);
               -   one hyphen or one space with the national call number is ignored;
               -   the corresponding international access code for the "J" TNIC is:
                  i)  72, if the national call number consists of 5 digits,
                  ii) 720, if the national call number consists of less or  more  than  5
                      digits.
               The international access code for all other  TNICs  follows  Recommendation
         F.69. For conversion between TNICs and F.69 codes, see also Recommendation F.69.
               An algorithm which meets the preceding criteria is shown in Figure 1/U.74.
                                 FIGURE 1/U.74 (Sheet 1 of 2) - CCITT 76200

                                 FIGURE 1/U.74 (Sheet 2 of 2) - CCITT 76210

         Note 1 - Check the automatic emitting speed and wait for the end of  the  answerback.  The
         answerback is considered to have ended after detection of a 300 ms period of idle.
         Note 2 - "Retry" refers to another attempt to trigger the answerback.
         Note 3 - Printable figures are combination No. 17 (1) to combination No.  16  (0).  Spaces
         (combination No. 31), hyphens (combination No. 1) and equal signs (combination no. 22) are
         allowed in this field, but are ignored.
         Note 4 - Are there one or two printable letters at the end of the answerback, preceded  by
         a space?
         Note 5 - Are there one or two printable letters following immediately the  "national  call
         number" (without space between), with space after them?
         Note 6 - In the case of a letter code single "J" corresponding F.69 code is:
                -    72, if the "national call number" is 5 digits long.
                -   720, if the "national call number" is less or more than 5 digits.
         Note 7 - Are there one or two printable letters following the "national call number",  and
         is there no further printable  character  following?  One  space  between  "national  call
         number" and network identification code is allowed.
         Note 8 - Are there one or two printable letters preceding immediately the  "national  call
         number" (without space between), but with a space in front of the letter(s).
         Note 9 - If unsuccessful, perform one retry after 1.5 seconds, if allowed in the protocol.
         Note 10 - If answerback is not received automatically.















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