You probably know by now that AT&T isn’t a fan of unofficial iPhone tethering, and they are now auto-updating accounts to paid tethering plans when they detect an iPhone users unauthorized tethering activity.

How AT&T Detects Unofficial Tethering from the iPhone

So how does AT&T know you are tethering in the first place? Apparently it’s very easy to detect from iPhone users, as AndroidPolice explains:

Jailbroken iPhones typically use the same tethering technique as a standard iPhone, the one that’s already present in iOS. This method exposes tethering activity quite readily, because the iPhone, 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.

In other words, AT&T simply looks at who is using tethered data through these APN’s, and then they cross-check these user accounts to see if they’re paying for a tethering plan. It’s that simple.



Hiding Unofficial iPhone Tethering Usage, or, How to Be Like an Android User

In order to understand how users will hide their tethering usage, we have to understand why unofficial tethering on Android isn’t taking the same heat from AT&T as iPhone users. Again AndroidPolice explains:

Android tethering, on the other hand, isn’t set up to route data through an alternate APN when the phone is in tethering mode – meaning AT&T would actually have to scan packets to determine whether or not you’re tethering. This requires diversion of AT&T’s resources (read: money), while identifying iPhone tethering is markedly simpler (read: cheap).

Because of this, AndroidPolice suggests that Android users may never have to worry about paying the unofficial tethering fee, because easy to detect Apple iPhone users dominate the AT&T subscriber base making them a more cost effective target.

In other words, if you don’t want AT&T to know you’re using an unofficial tethering app, you have to hide this by behaving more like an Android tethering app and not using the alternate APN’s. Currently, this ability is limited to the newest version of PDANet, which has a “Hide Usage” option in the app.

I’m not going to recommend using this approach to hide tethering usage, while I disagree with AT&T’s crackdown, they clearly doesn’t want users tethering without paying a fee. It’s their service, we signed up for it, we play by their rules. Is it fair? Many including myself don’t think so, but that’s the way it goes. Why bother jumping through all these hoops when you can just pay an extra $20/month and not have to worry about it?

(btw that awesome Death Star AT&T logo is also from AndroidPolice)