Unable to hear audio from Asterisk server

Question

I am running an Asterisk server in Public IP. When I connect SIP softphones to the server, I am able to make call and conversation is possible between the softphones. However, anything that is played on the asterisk server is not heard in the softphone. In asterisk server log, I could see the message like " Playing 'hello-world.gsm' " but I could not hear any message.

Ports open for sending and receiving UDP packets in the server are 5060, 10000 to 20000, 4569, 5036 and 2727

When I setup the server inside the LAN, everything was working perfectly. So I suspect it could be related to some firewall configuration. Please help me.

Note : SIP softphones were running in a machine connected to internet using wifi dongle with Cone NAT

Answer 1

Just to clarify it seems like your asterisk box is on a LAN, and there is a NAT device which provides the public IP address. In this case, you should configure asterisk for network address translation.

In sip.conf set the following parameters to their correct values:

directmedia = no
nat = force_rport,comedia
canreinvite = no
insecure = port,invite
localnet = 
externip/externhost =

Use the sip set debug on command to verify asterisk replaces it's local address with the externip in sip dialogs to your public clients.

Also rtp set debug on can be used to show if audio (RTP) packets are reaching the asterisk box.