AT&T is able to easily identify unauthorized tetherers resulting in warning notices for customers, according to a new report. Android Police says that this is because of the tethering technique employed by that uses an alternate APN.
Jailbroken iPhones typically use the same tethering technique as a standard , the one that’s already present in . This method exposes tethering activity quite readily, because the , when in tethering mode, sends traffic through an alternate APN (AT&T access point/router) for the express purpose of identifying the traffic as tethered data. This makes it extremely easy for AT&T to identify whether or not an iOS device is utilizing tethering, and just how much of their data is consumed via tethering.
Some tethering applications for iOS make use of alternative methods and route tethered traffic through the phone’s normal data APN, but by and large, most jailbreakers stick with the stock application because it’s easy to use and doesn’t require any complicated setup. In fact, many iPhone users for the sole purpose of avoiding AT&T’s tethering fees (for why, see next section). These are the people AT&T’s is going after.
Recently JuneFabrics released an update to their PdaNet tethering app for iPhone which claims to be able to hide your tethering usage from carriers. There have been mixed reports on its success.