How do cell phone data plan's handle a phone's IP address?

Question

I noticed when using my phone's data access that I have a public IP.

How is the network setup with this (using Verizon):

1. Am I behind a proxy server and the IP is the proxies, not my own?
2. If not, is there some restrictions or firewall prevention malicious activity to my phone on the Mobile Company's side?
3. If not, could I write a server application for my Droid, and connect to it from any computer on the internet?

Answer 1

Yes/No, Yes, No.

Most likely the IP is internet-facing, but with firewall policies to prevent back connections.

This prevents intrusion attempts and precludes the possibility of running any server application

Answer 2

Its a good bet that you are behind a proxy server. Try going to whatismyipaddress.com from your phone's browser. It has pretty good proxy detection.

I can't comment on the Droid but on my BlackBerry I can find out my phone's real IP address using its built-in connection diagnostics.

It may be possible to write a server application and host it on your cell phone even from behind a proxy but it would most certainly be a violation of your cell companies terms of service. I would read it very carefully before trying anything or you may end up being dropped.