No audio

I'm evaluating the WCS4.
My environment is the following:
your webphone -- wcs4 -- asterisk -- pstn (my mobile)
The webphone successfully registred on asterisk, the call is successfully established, but when I answer the call I have no audio on both sides.
Can you please help me to find the issue?



Staff member
Are WCS4 and asterisk located in the same network?
Where is located web browser?
Full path is:
Browser - WCS4 - Asterisk - PSTN
So if all these in the LAN, you have to set local IP address in both conf/ fields
ip = {local network interface IP}
ip_local = {local network interface IP}
For first testing we recommend a server with public and static IP address and stopped firewall.
If your server is accessible via SSH you can send us ssh access to
We will check the installation. You may also send us logs: pcap and flashphoner conf and logs folders.
Pcap dump:
tcpdump udp -s 2048 -w log.pcap


Staff member
solved by
The cause of 'No audio issue' is closed UDP media ports used for WebRTC.
By default its range is [31000-32000]. It is configured in /usr/local/conf/

So when a UDP packet sent to externalIP: [31000-32000] it should be routed to this host host IP and the same port.
Therefore browser's UDP packets are not received by server. And it is cause of issue.

Please setup NAT/firewall for these ports then it should work.