TURN server
What is a TURN server?
A TURN server (Traversal Using Relays around NAT) is a relay that carries a call's audio and video when a firewall, VPN or home router stops a device from reaching the media server directly. It is the fallback that lets a call connect from a hotel, an office or a school network that blocks the usual routes for real-time audio and video.
How does a TURN server work?
Real-time media prefers UDP, a fast way of sending packets that does not wait to resend lost ones. When a call starts, the device collects possible routes to the media server: its own address, the public address its router shows to the internet (found with a small helper called STUN), and a relay address on a TURN server. A process called ICE tests these routes and keeps the best one that works.
If a firewall blocks the direct routes, the device opens a connection to the TURN server instead, over UDP, over TCP or over TLS on port 443, the same port secure web pages use. The relay then passes packets between the device and the media server in both directions.
| Route | When it is used |
|---|---|
| Direct UDP | Ordinary home and mobile networks. The best quality. |
| UDP through a relay | The network allows UDP but not a direct route to the media server. |
| TCP or TLS on port 443 through a relay | Strict networks that allow little more than web browsing. |
Why does a TURN server matter in a video call?
Without a relay, a strict network produces a confusing failure: the meeting page loads, the lobby works, but the call never connects or shows black tiles. A TURN relay over TLS on port 443 looks to a firewall like ordinary secure web traffic, so it gets through most networks that allow browsing.
The relay cannot read the call. The audio and video stay protected with the call's own encryption in transit, and the relay only forwards the encrypted packets.
How does Meeto use TURN?
Each participant receives relay credentials when they join a Meeto call, covering UDP, TCP and TLS on port 443. The device picks the route by itself; there is no setting to change. If a network keeps dropping the call, Meeto can also switch to a stable relay route during the call and says so with the notice “Unstable network — switched to the stable relay route”.
Guests can run a check from the lobby with “Test your connection”, which reports whether signalling, the video channel and the “Backup relay (TURN)” work. If every route fails, it suggests trying a different network. The firewall troubleshooting guide takes it from there.
Frequently asked questions
Does a TURN relay slow a call down?
It adds one more stop on the way, and a relay over TCP or TLS copes less gracefully with lost packets than a direct UDP route. That is why a call uses the relay only when the direct routes fail; on a network that blocks them, the alternative is no call at all.
Do I need to set up my own TURN server to use Meeto?
No. Meeto provides the relay and hands each participant the credentials automatically when they join. There is nothing to install or configure on your side.
Is a TURN server the same as a VPN?
No. A VPN reroutes all of a device's traffic through another network. A TURN relay carries only the call's media to the meeting service. A VPN can even be the reason a call needs the relay, because many VPNs block the traffic real-time media prefers.
What should I ask my IT team to allow?
Ideally, outbound UDP traffic to the meeting service, which gives the best call quality. At a minimum, outbound TLS on port 443 to the relay must work. The firewall troubleshooting guide lists the symptoms and the information to send.
Put it to work
Open your Meeto account to set it up, or explore the working product first.