[SR-Users] Kamailio Failed to have audo converstaion with RTP

Dear Daniel , I thank you for your reply , I have a server having the Astersisk ip address (192.168.10.15) , and rtp + kamailio is installed on an another pc have the following ip (192.168.10.17) which is linked to the Astersik , and on the same pc , another network card exists having the ip address (192.168.20.3 ) which is linked to a client pc having the ip address ( 192.168.20.4) . I tracked the call and i can see SIP ACK nd BYE between 20.3 and 20.4 but there is no audio conversation this is my configuration file for kamailio attached above . P.S : testing without NATING as described in the above setup . I thank you alot again for all your help .