I just noticed that there are 192.0, not 192.168 addresses, and the whois entry for the “ISP” doesn’t look like an ISP, to me. I think there has been confusing redaction here! Doing NAT between public addresses is not something that should be happening.
However, taken at face value, the transport for that endpoint needs to have signalling and media addresses 192.0.3.1, and local network is probably 192.0.2.0/24, although you haven’t said what the inside address of VDM is. I don’t though, know how well chan_pjsip handles this sort of, multi-transport, situation, and I’m pretty sure you have to go outside the FreePBX GUI to set it up. chan_sip does not handle such configurations, at all.