SS7-ISUP, DSS1 Call reference

SS7-ISUP Call reference


           8  7  6  5  4  3  2  1
        1     Call identity
        2     Call identity
        3     Call identity
        4  Sign. point code .. LSB
        5 Spare | MSB.............
Call identity - A code expressing in pure binary representation the identification number allocated to the call.
Signalling point code - The code of the signalling point in which the call identity is relevant.

DSS1 Call reference

The purpose of the call reference is to identify the call request at the local UNI.

    The fields of the call reference information elements are:

           8   7   6   5   4   3   2   1
          +--------------+---------------+
          |0   0   0   0 |lenght of Crv  |
          +--+-----------+---------------+
          |f |   call reference value    | <- BRI   f=0 origination side, f=1 destination side
          +--+---------------------------+
          |      call reference value    | <- BRI PRI
          +------------------------------+
Call reference values are assigned by the originating side of the interface for a call. The numerical value of the global call reference is zero.