SS7 - ISUP Forward call indicators parameter

           8  7  6  5  4  3  2  1
        1  H  G  F  E  D  C  B  A
        2  P  O  N  M  L  K  J  I

A               National/international call indicator
0               call to be treated as a national call
1               call to be treated as an international call
               This bit can be set to any value in the country of origin.
               In the international network this bit is not checked.
               In the destination country, calls from the international
               network will have this bit set to 1.

C B             End-to-end method indicator (Note)
0 0             no end-to-end method available (only link-by-link method available)
0 1             pass-along method available (national use)
1 0             SCCP method available
1 1             pass-along and SCCP methods available (national use)

D               Interworking indicator (Note)
0               no interworking encountered (No. 7 signalling all the way)
1               interworking encountered

E               End-to-end information indicator (Note) (national use)
0               no end-to-end information available
1               end-to-end information available

F               ISDN user part indicator (Note)
0               ISDN user part not used all the way
1               ISDN user part used all the way

H G             ISDN user part preference indicator
0 0             ISDN user part preferred all the way
0 1             ISDN user part not required all the way
1 0             ISDN user part required all the way
1 1             spare

I               ISDN access indicator
0               originating access non-ISDN
1               originating access ISDN

K J             SCCP method indicator (Note)
0 0             no indication
0 1             connectionless method available (national use)
1 0             connection oriented method available
1 1             connectionless and connection oriented methods available (national use)

bit L           Spare
bits P-M        Reserved for national use

NOTE - Bits B-F and J-K constitute the protocol control indicator.