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 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).