I was testing the freeswitch with the gateway and when I make two outgoing calls and bridge them together, I am not able to hear the audio. But as soon as I played something on any one of the channel, both the parties can be able to here the audio. 

Did anyone face this kind of issue? Can you please help me to solve the issue? 

My machine is running on AWS behind NAT and i have done all the configuration that is specified in the freeswitch wiki page. 

P.S : when I make one outgoing to sip user and another outgoing call via SIP gateway everything works fine(both the parties able to hear the voice).