Provide bridge connection route between different sim card operator

2 ports (G=G,G=C,C=C),One pair of bridge connection        ,1BGG/1BGC/1BCC
4 ports (G=G,G=C,C=C),Two pairs of bridge connection     ,2BGG/2BGC/2BCC
8 ports (G=G,G=C,C=C),Four pairs of bridge connection     ,4BGG/4BGC/4BCC

For example: A B C D  4 sim cards,  A & B belong to one operator X,  C & D belong to other operator Y

             B C are pretended to equipment ,
             A want to call D,
             then A call B at first,  then B bridge connection C,  C call D from A,
             Begin the talking between A and D.