How AT&T Tracks Tethering Usage

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A few months ago, we reported that AT&T is starting to crack down on iPhone tethering usage. Jailbroken users are able to tether without subscribing to an extra plan. Some new information has emerged regarding how AT&T determines who’s tethering.

In a post by Android Police a few weeks ago, it was mentioned that a separate APN (access point name) is used for a separate tethering plan:

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.

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 jailbreak 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.

If you’re jailbroken and would like to continue to tether, then it’s recommended to use PdaNet (see the screenshot above). It’s personally my favorite way of tethering, and it’s been around for quite some time (since September of 2008).

The latest version of PdaNet (version 5.01) has a new toggle, called “Hide Usage”. This, supposedly, uses the default data APN for your iPhone (instead of the tethering-specific APN). We’re not exactly sure what the different levels do. We’ve reached out to June Fabrics for some information regarding this, and will update this post once we receive it.

Now that this information has spread all around the web, I’m sure AT&T (and other carriers, for that matter) are looking for new ways to block people from tethering without paying for it (come on, why pay extra for a tethering plan when we’re already paying for data?).

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[via Redmond Pie via Android Police]