Having had cell phones and wireless for a few years. I actually wondered what that port would be used for. I mean...What do you pay for the privilage to use a phone when your camping? Then use long distance to call your ISP or something? On dial up? Yikes!
If you have a laptop or computer made in the last 5 years it will probably take a cheap Wi-Fi card. Seems a lot less effort.
Free RV WiFi sites