ICE, STUN, and TURN are used to establish a MEDIA connection between two devices on different networks separated by firewalls and NAT servers. They do not apply to signaling between devices which means that if you cannot establish a signaling connection between the two devices then ICE, STUN and TURN are irrelevant. There must be a signaling connection established and only then will the devices attempt to establish a media connection.
How they are used to traverse media through a Firewall and override the issue caused by Network Address Translation (NAT)? What is the role of each protocols? what are the differences? how the interaction occurs between STUN, TURN and ICE.
Through this article, STUN TURN and ICE are demystified through a Call Flow with two scenarios:
Two MRA Endpoints and WebRTC with Cisco Meeting Server