I set up an R-Pi 3G Modem combo with wvdial and it's working perfectly. I can access everything on the internet from the Pi. But when I try to access the Pi from the internet there is nothing, zero connection. As far as I can tell there is no firewall so I have no idea what blocks the data. If I connect the Pi to my LAN I can access it through my local network.
Can't access Rasperberry Pi over the internet
ppp;3g;wvdial
Possibly, your 3G provider gives you a private IP address from one of these ranges10.0.0.0 - 10.255.255.255172.16.0.0 - 172.31.255.255192.168.0.0 - 192.168.255.255In this case, you're behind ISP's NAT and can't access Pi from the internet, but you can access the internet from Pi.