Currently, the official vMix Call TURN servers are reachable on ports 10349 and 443, both on TCP and UDP.

Access on TCP port 443 exists as a way to counter firewall restrictions on locked-down corporate networks, where outbound traffic is restricted to the bare minimum for security purposes. It works most of the time, because port 443 is used for HTTPS traffic and hence blocking it would cause web browsing issues for users.

Modern firewalls are getting clever and can notice when traffic on port 443 isn't actually HTTPS and block it, causing issues with vMix Call on corporate networks. HTTPS is based on TLS (formerly SSL) and firewalls that can detect HTTPS usually detect the TLS part without being able to go further in their inspection because the connection is encrypted between the client and the server.

In addition to TCP and UDP, TURN also supports TLS transport. So my proposal is to add TLS connectivity on the official vMix TURN servers to increase the chances of vMix Call working behind corporate networks.