How to connect to the server of the mobile in 3G?

I use NetworkManage’s Unity and I want to connect P2P between two mobile How can I do this in a 3G network?

Hey.
I use NetworkManager Unity3d The question is how can I make my phone a server that I will be able to accept requests from the client I use on the phone’s network (3 \ 4G).
I use wifi and I do port forwarding so I can get requests from the client
But the problem I’m using is the 4g network of the phone so I can not do port forwarding
Can I do?