send SIP traffic from cloud to local server without port forwarding

I have 2 debian servers for telephony, the local server is connected to sip phones and the cloud server must send the calls to the local server, but the issue is that my ISP blocks port forwarding completely, so I want to make a tunnel whether it's OpenVPN or WireGuard or whatever to be able to send sip traffic from the cloud server to the local server, I need help to make this tunnel