2.1 Backgrounds about SIP Trunks
The SIP Trunks are used for connecting PrivateServer to a local PBX or to a SIP Voice provider. The above statement implies that a Trunk can be used both for receiving and placing calls in a bidirectional way.
The PrivateServer is designed to perform always as a client when configuring a SIP Trunk. This means that PrivateServer itself can not act as a Trunk Provider.
Even if each SIP Trunk can be used to both receive and place calls, PrivateServer has to be properly configured in order to act in a bidirectional way. By default the Inbound Trunks are configured for enabling the calls directed to external number through a different PBX. They can be later set up to let the PrivateServer receive incoming calls from a different PBX. This setup is made promoting one Inbound Trunk as an Outbound one.
From the PrivateServer version 2.5 you have two main SIP Trunk's Families:
- Secure Trunks
- Unsecure Trunks
The former ones entail both TLS and SRTP, while the latter none of them: they use just RTP over UDP (thus without TLS). Which one is to be used depends from many factors, major one is the kind of PBX on the trunk's end. For example Cisco Unity Call Manager and Avaya PBX are usually connected to PrivateServer via Secure Trunk, while SIP providers like Messagenet uses the Unsecure Trunk.
Apart the Trunk's Families you should familiarise with the Authentication model, that can be:
- Registered
- Unregistered
For each of the Families and the Authentication Models you are going to find a specific manual page describing the correct configuration and the possible parameters to be used.