I have an Asterisk server configured at home. It works well, and I am able to make calls to other devices internally over LAN or Wi-Fi - as well as outbound to a VoIP provider. I use CSipSimple as the client on Android (and Jitsi on my Ubuntu laptop).
I have also configured an OpenVPN server, which is also working as expected for both Ubuntu and Android devices. I can ping, ssh, etc across it.
I want to be able to make a call to a LAN or Wi-Fi client at home, over the OpenVPN connection from my Android phone using CSipSimple (I haven't allowed Asterisk clients to register from the Internet, only from the LAN subnet).
CSipSimple is able to register and make calls - but I cannot hear any incoming audio on my phone. The call info shows no packets coming in. Calls over OpenVPN using Jitsi on Ubuntu work properly, but CSipSimple on Android does not work.