I am having some strange problem of one way voice without any NAT.I am having pstn gw on public IP, openser on public IP, and a SIP client on public IP.I am able to dial from outside phone to my SIP client. When I try to talk , the voice passes only in one direction, i.e..from SIP client to my outside phone, and not towards other side. What is the reason of this problem. Please help me.openser is having all default configuration where anyone with any name and password can be allowed to dial.