WCS is not a SIP server, it is a WebRTC-SIP gateway server. So you need a standalone SIP PBX (OpenSIPS, Asterix etc). In this case:Maybe i haven't been clear in my previous post, we only need voice NOT video, so maybe we could setup webcallserver to act as a sip just for internal calls of users attache to our internal vpn network. This way it would be easy to have a sip software working on a raspberry.