assuming a basic setup:
virtual or physical machine (assume local p is 10.0.0.10) with nettalk running on port 88(or 80, whatever).
your router has an Internet IP (if things are simple, whatismyip.com running from a browser on your nettalk server will tell you)
Ideally you have a domain name that points there already eg: Mynettalk.com
thats the ip users can use.
on the router you MUST forward the port that the users will Use to access your nettalk server assume 80 to the local
ip and Port that your Nettalk is running on 10.0.0.10 and port 88.
so an outside user can use " mynettalk.com " traffic will go to your nettalk server
i assume this how most folks use web facing Nettalk apps. it could be more complicated,...
if your router already uses port 80 you can use different port eg 88, so the user would have to enter mymettalk.com:88
if you have access to your Domain Setup there are a number of ways to make it easier for the user for example
you could forward the domain or a subdomain directly to the correct ip and port.eg: cloud.mynettalk.,com
make sure your nettalk servers firewall is not blocking your. port.