Connecting to internal Asterisk PBX

Good morning,

I’m a new user, and have so far been successful in setting up my PBX, SIP Trunk with Digium, and have registered 2 hard phones and a soft phone (can place and receive external calls).

My next endeavor is to deploy a phone to a customer located outside, and have their phone communicate with my PBX.

My LAN topology in a nutshell: ISP <–> border router <–> ASA Firewall <–> LAN
ISP=68.x.x.x; border router 192.168.0.x; LAN 192.168.1.x

I only have a single IP from the ISP, which is redirected based on incoming Port. So traffic from a remote phone using (for example) UDP Port 10001 would go to my public IP address. When the router gets it, it will forward to the firewall. The firewall gets it, and (based on a static mapping) directs it to the correct internal address. In this case it goes to the PBX, based on the incoming UDP port.

I know this must be a common scenario. But so far I’ve not been able to locate a FAQ or tutorial on how to make it work. Please let me know if you have any ideas or can point me in the right direction.

Thank you!

Google has many tutorials about do that. My recomandation is to setup a VPN with openvpn and connect external clients using that VPN.