https://github.com/meetecho/janus-gateway
We have upwards of 100 simultaneous users on it every day, and at the moment it seems to be 100% reliable.
https://www.mizu-voip.com/Software/WebRTCtoSIP.aspx
It has a nice config wizard and built-in STUN and TURN server.
https://github.com/meetecho/janus-gateway
We have upwards of 100 simultaneous users on it every day, and at the moment it seems to be 100% reliable.