Hi ,

     Can someone explain me what is \1 and \3 doing in the subst expression ?

Input        :                    From: <sip:anonymous@10.211.160.168>;tag=41008079_nab_FFFF_isp_FFFF_cco_FFFF_igo_FFFF_mgt_78DD

subst('/^From:(.*)10.211.160.168(.*)>(.*)/From:\110.211.160.174>\3/ig');

Output     :                  From: <sip:anonymous@10.211.160.174>;tag=41008079_nab_FFFF_isp_FFFF_cco_FFFF_igo_FFFF_mgt_78DD

Regards,

Mahesh.b