If you are trying to break through a firewall you don’t own then that’s not legitimate.
replyIf you are buying firewall as a service then request a user interface or change your service provider.
Are you even acknowledging my example? Where does it exist in your bimodal model of reality of "my firewall" and "somebody else's firewall"?
replyWhat provider would you suggest somebody wanting to make VoIP calls on their smartphone switch to that allows port forwarding of the kind you describe? And which popular VoIP app would support statically forwarded ports like that?