[SkyPuncher]

Just because you have a US IP address, doesn't mean traffic actually gets routed through it.

My limited understanding (from one uni course) is mobile devices get a secondary identifier that the networks use for the actual routing process. While a device may officially identify as having a US IP address, the cell carriers communicate a secondary, current IP address/identifier local to the device's current position.

It's much like how DNS works. You don't route all traffic through a DNS server. You send it a readable name, then communicated directly with the IP address that's returned.

[zakki]

This is how your mobile data traffic is served by your operator:

In 3G/LTE network there are terms called Gn interface, Gi Interface, Gp interface and many others. Gn is to manage your mobility. From Gi you will get local ip address and internet access. From Gp you will be routed to you own cellular operator Gp interface.

When you are on your original cellular operator network, you will be served by Gn and Gi interface for your internet access. When you are roaming, you will be served by Gn and Gp interface of local cellular operator that will forward to your original cellular operator’s Gp. After that it will routed to Gi interface of your original cellular operator.

edited: Gn function