This issue is generally due to clients having problems setting up the media path to the media broker.
Please check the following:
1. Media Broker configuration issues
- CIDR configured on Sip network doesn't pick up the media broker's internal traffic interface.
- The Sip network CIDR is configured as 'all' but you have interfaces for both external and internal traffic on the Media Broker.
- Wrong IP configured on WebRTC local address (can't be 127.0.0.1)
- Wrong IP configured on WebRTC external binding (can't be 127.0.0.1)
- Please see Understanding MediaBroker Ports for more information.
- If no Media Broker is configured the call will not set up in the first place.
2. A firewall is blocking the media path
- The WebRTC public port (defaults to 16000) is not open on all firewalls between client and media broker.
You can check this externally from a simple port checker like https://pentest-tools.com/discovery-probing/udp-port-scanner-online-nmap
- The firewall not configured to forward from WebRTC public Address/port to local Address/port
3. A VPN is blocking the media path
Some VPNs may not be configured to allow 2 way UDP. Clients connecting via VPN may experience no Voice and Video. An indication of this problem may be seen in the media broker proxy.log with the following error message repeatedly output.
ERROR com.alicecallsbob.porth.rtp.proxy.routing.ProxyConnection - can't processOutgoingPacket for RTCP because remote is null
A PCAP trace may also show no STUN responses to incoming STUN requests from a client connecting via a VPN. In the following image no STUN response is seen leaving the Gateway.
4. Video device needs to support h264 or VP8
The media broker can transcode h264 and VP8 so endpoints need to be able to support one of these codecs to ensure end to end video
5. Mic and camera are not available
Firefox and IE will not share the camera with other apps. Please ensure these browsers have access to these media inputs