The settings of CoWork Calls are set by default so that conferences via voice and video immediately work GDPR-compliant if all participants have a connection to the internet. For the negotiation of the voice and video connection, an STUN server¹⁾ is required, which is pre-populated with services located in Germany. The actual voice and video connection then takes place exclusively on secured channels between the participants.

If the negotiation of the connection is also to take place in the local network or via other, private servers, the default setting can be changed.

At least one STUN server is required to exchange connection data between the participants of a call. The STUN servers are asked for information on which IP and port the respective client could be reached. The clients then set up their own network among themselves, over which voice and video are transmitted in encrypted form.

Examples of public STUN servers can be found here.

To revert to the default servers, all servers can be removed and then saved.

Note: No more than 5 servers should be entered because otherwise the connection setup can be negatively affected.

A TURN Server is being used as a relaying party when no other connection candidates can be found between end clients. That means that, e.g. one client is available by IPv6 only while another is available via IPv4. In that case, both clients can not directly establish a connection for audio and video calls. A TURN server mitigates this problem by offering separate connections to both end clients and linking them internally.

TURN servers usually require an authentication which can be provided via username and password. The most popular TURN server is CoTurn, which can also be self-hosted.

Note: No more than 5 servers should be entered because otherwise the connection setup can be negatively affected.

The Transport policy defines how the registered TURN servers are to be used:

• All connections are allowed (public IPs and relayed connection): The best option for connecting the clients to each other is determined automatically.
• Only relayed connections are allowed (only TURN servers are used): The TURN server is always used to connect the clients to each other.

The Connection Settings are used to define the way in which the audio and video connection between the participants of a call will be established. Depending on your server's environment, you can select Dynamic settings where the i-net Clear Reports server determines connection ports automatically or select Fixed to provide specific connection ports.

• Timeout: How long will a user's call be kept alive for other participants, when the user's connection went bad.

Like a web server, the server must be directly accessible from the browser on the specified port and optional external address. This port must be open in the firewall in front of the server. If fixed ports are set, no STUN servers are used to get through a firewall. The STUN servers are only used by the browser to get through the firewall of other clients.

• UDP Port: the fixed UDP port to be used for connections
• TCP Port: the fixed TCP port to be used for connections
• Public NAT addresses: is required if the local IP address of the server is not the address that the browser sees from the outside, e.g. because:
  • the server is behind a reverse proxy
  • or port forwarding to the server is used in a firewall
  • or the server is running in a Docker container and the port has been published with the parameter –publish (-p)

Note: A fixed port assignment may also be necessary if the server is running in a Docker container, as no dynamic ports can be opened here. An exception would be the use of the host network. It is recommended to define both UDP and TCP ports and assign both to the host system.

Dynamic ports must be used if the i-net Clear Reports server cannot be reached directly by the browser because it is located behind a NAT or firewall in an internal network. A connection is established from a local dynamic port via an external STUN server. The server must allow outgoing UDP connections from the configured port range to any address, including the STUN servers.

• *Minimum UDP Port: The minimum port to be used for UDP connections. It is deactivated with the value 0. Maximum UDP port:** the maximum port to be used for UDP connections. It is deactivated with the value 0.
• The ports must be in the range 1024-65535. If no ports are defined, they are determined by the system. Specifying the port range also determines the number of clients that can be connected at the same time.

Call Reactions are a list of emojis that can be sent in a connected call session. They are intended to provide feedback to the speaker or cheer up the conversation. The configuration of the list enables administrative users to make sure which emojis can be sent to a conversation.

Note: the reactions are restricted to the configured ones for the WebAPI as well.