Naven
Glossary
Firewall
A filter that decides which network traffic is allowed.
Corporate and school networks commonly block by domain, by category, or by protocol. A messenger can be unreachable because its domain is on a list, because its media ports are closed, or both — and the two fail differently: the first stops the site loading, the second lets chat work while calls silently never connect.
Relay servers exist largely to survive the second case.
Where Naven stands
Naven's calls fall back to a relay when direct connections are blocked, so a call still connects on a restrictive network. A blocked domain it cannot and should not work around.