STUN and TURN Servers

The configuration of the telephone system itself is located under Infrastructure under Network ▸ Telephony. For the visualization, additional servers can be configured in the Network Interfaces and in the Remote Access.

If possible, no STUN and TURN server configuration should be used. A misconfiguration can prevent a voice connection from being established. In addition, the servers used must always be trustworthy.

STUN Server

The STUN server resolves all public addresses behind a NAT for the participant. These addresses are used by the participant to establish a connection with the server. This configuration requires opening the VoIP UDP range when using a firewall.

Note: Connection establishment can take very long when using a STUN server, as each individual address is tried one after another.

Example Scenario

Participant (10.0.0.100/24) ▸ NAT (192.168.1.88/24) ▸ Telephone System

Participant (10.0.0.100/24) ▸ NAT (192.168.1.88/24) ▸ STUN Server

Connection establishment occurs simultaneously to the NAT address (192.168.1.88/24) and to the participant address (10.0.0.100/24).

TURN Server

When a TURN server is used, the UDP packets are sent directly to the TURN server. This then connects the participants with each other. This may result in higher latencies and reduced audio quality. Configuring a STUN server is not required if the TURN server is not located behind a NAT.

The settings of the TURN server must be configured simultaneously in the telephone system under Infrastructure under Network ▸ Telephony and also in the used Network Interface or in the Remote Access. A username and password are always required to use a TURN server.

WARNING: Do not use unknown public servers. This can lead to conversations being overheard. In addition, availability is not always guaranteed.

Note: The username and password of the TURN server are always transmitted in plain text to the visualization. Be sure to use different passwords for the visualization or configuration.

Example Scenario

Participant ▸ Firewall ▸ TURN Server ▸ Firewall ▸ Telephone System

The packets return via the TURN server. This acts as a relay between both endpoints.

Internal Servers

Antcas Control has its own integrated TURN and STUN server starting from Core 2. These can be configured via the telephone system settings under Infrastructure under Network ▸ Telephony under Advanced. The servers support both unencrypted and TLS-encrypted connections over the same port. The UDP and TCP ports of the services are always identical and cannot be configured separately. To also support the RFC 5780 standard, an additional alternative port is automatically used. This port is always one higher than the normal port.

Note: The username cannot contain a colon (:).

Public Servers

Antcas offers public servers in the portal. These support both UDP/TCP and DTLS/TLS connections.

• STUN: service.antcas.com:6897
• TURN: service.antcas.com:6897
  • Username: antTURN
  • Password: BlowingAntsX7000
• STUN: stun.l.google.com:19302

Note: Use of the servers at your own risk! Antcas does not guarantee that these servers are always available.