How Does AT&T Detect Unofficial iPhone Tethering?

iPhone Tethering

As we’ve reported earlier, AT&T continues to clamp down on unofficial iPhone tethering, which is one of the main reasons users jailbreak their iPhone.

There has been a lot of debate and speculation on how AT&T detects the unofficial iPhone tethering. Android Police has provided some insight into how AT&T is able to identify users who are using the unofficial tethering option.

Android Police 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.

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.

According to Android Police, popular jailbreak apps such as MyWi and Tetherme use the tethering APN instead of using the normal data APN.

It’s not clear if PdaNet that has been updated recently to hide unofficial tethering by masking the packets uses iPhone’s normal data APN to go undetected (assuming it does). If PdaNet’s solution works then we’re quite sure that other developers will soon release an updated version of their jailbreak apps to stay ahead of the cat and mouse game with AT&T.

It is unfortunate that carriers are charging users for the tethering option or don’t allow some features or apps to work to use iPhone’s 3G data connection (work only over Wi-Fi). Ideally, we should be able to use the data the way we want as we’ve paid for it.

What do you think?

Like this post? Share it!
  • Totally agree. I’m paying my $30 for unlimited, I should BE unlimited.

  • ericdano

    Unlimited means that, unlimited. The fact that I have a iPad or whatever using the connection should not matter. It’s UNLIMITED.

    • Yo Mama

      Nope… read the fine print. It’s <2GB

      • Melvarius

        which by default makes it limited. the corporates are just so used to B’S-ing to get their grubby little paws on your cash.

        Dictionary definition: without limits or bounds…

        Corporate Definition: Whatever we say it is. Now shut it and give us your cash….

        the Fair useage cop-out that they try to cover their sorry a$$eS with imposes limits and therefore still means that the use of the term UNLIMITED is illegal / blatant lie.

        • Melvarius

          I’m not a legal bunny by any stretch of the imagination but wouldn’t they, (AT&T), be in breach of the contract by implying UNLIMITED then imposing limits? Using the term Unlimited is misleading and a mis-representation of the deal on offer.

  • Macsimos

    I have had the unlimited data plan for a few years, and yet it really isn’t unlimited. Having to pay for tethering is a complete rip-off. The ability to tether was one of the reasons why I jailbroke my iPhones in the past.

  • JB

    I think if these people check their unbilled data usage on AT&T’s website they will see their tethered traffic showing up as “broadband”. Just saying…

  • Dont Bite the Forbidden Apple

    Just to piss off At&T- you should buy an airplay, and stream neflix to your TV, via ATT 3g, all day long.

    • Tony

      Much like anyone using large amounts on their iPhones, AT&T will simply change or terminate your contract if you use too much data. Try going over 10GBs on their unlimited plan (completely legitimately)… you get a text saying continued high data use will result in additional charges or termination.

      • Itsyaboy

        That’s not true I go over 10 gbs every month about 11 or 12 watching netflix downloading games albums movies etc and I never got a message like thT

      • Jason

        10GB? lol dude your an amateur. I had a constant 120GB/m AVERAGE. I’m the only one that has netflix and My3g working together. The fact of the matter is AT&T is the fastest download that i’ve experienced aside from a cable/wifi combo. I got the text form AT&T saying that its tethering plans aren’t free and stopped jumping the turnstile after that warning. But I still avarage about 80GB/m. Anything less would be uncivilized. I can’t wait till i get confo on wether or not it can be avoided or AT&T just gives it away for free ie Sprint.

      • I just started using tethering as my main way for internet at my house. I called ATT to straighten out a bill and they automatically routed me to a department to talk about tethering being detected. I totally renounced it and said I use the internet a lot and look at a lot of videos. She asked if I wanted a tethering plan and said no, I don’t use it. Apparently they are going to keep monitoring it, I threatened to cancel my service and go to someone else. I have unlimited data, why the fuck should it matter. I’m so sick of ATT!!!!!

        • Oh yea, I forgot to mention, this month (July) I’ll end up with about 8 Gigs of usage lol. Fuck em’

      • Bay Area CA Male

        Tony… You are wrong!!!

        I have used OVER 150 GB’s on a regular basis for years! My peak month was at 192GB’s for one iPhone and I have 3 iPhones on my Fam Plan.

        I always got away with it, they never said ANYTHING!!!… And until recently i was still using that MiWi app to stream netflix and youtube thru my laptop to my TV.

        But just as someone stated above, now I will buy Appe TV to use that feature now… And Ill leave it running all night every night to teach them a lesson!!!!

        Im going for 300GB this month now!

  • jdb

    I jailbreak for four reasons:
    In-app texting
    sbs settings
    3G unrestrictor
    Other than that, I don’t really mess around with the looks or style of the phone. I only hope my tethering continues to go unnoticed. I’ve only tether about 95 mb between this month and last, and I use typically about 800mb-3gb on an unlimited plan. Am I tethering just enough to slip through the cracks? I haven’t received a notice at all…

    • Bay Area CA Male

      Hey buddy can you let me know which tethering App you use?

      If this artcile is correct then it means some of them use the native tethering APN as opposed to the “standard” or “default” APN which would trick them!

  • Rob

    It’s a straight out rip off. I pay for unlimited data so it should be just that. And as it’s mine it should not matter to AT&T how I choose to use it. if I buy an iPad why should I have to pay twice to use it with my phone?

  • Just visited in the UK, when i used O2, every action i have performed was tracked. When i switched off 3G on iphone, i have immediately received an offer for unlimited surfing for the rest of the day for 1£. The same special messages (not SMS, some pop up right on the iphone) appeared on different situation while using the iphone.
    My point is… Forget about it, your device is being tracked with every move you make, whether you like it or not.

    Sent from my iPhone. (tracked or not, this is still the best gadget out there)

  • Has any one tried to tether iPhone to iPhone?
    I wonder how that looks to AT&T. The last time the ” how does AT&T know” debate came up people were saying they look at the User agent so this might be a good test.

  • Mikekryptonite

    Anyone get the message using PDANet 5.01, to tether an IPAD to an Iphone (using level II security)? It seems this would be the least likely way to get the message.

    I may be wrong, but I was thinking traffic from a mobile device would be less likely to detect than from a pc or mac.

    Anyone have any experience with this? Would like to know if PDAnet is the current solution to this problem.

    • RiffRath

      It makes no difference what device you are tethering to it. It only matters what app you use to do your tethering.

  • jussayin

    well just to let you people know the whole business model is going to change in telecoms and every one will pay a much higher price the point is at the moment who will pay directly, either the content providers (which will pass in on to the consumer) or the consumer for different quality/type of service. the fact is the content providers are making millions if not billions every year but it is the telco’s who are spending the billions to create the networks to carry the content, these networks typically last about 5 years then they rebuild. and all the while the price erosion for the customer has made them less and less money. people moan about their bills but look back a few years and look how much you were charged for just voice, and cable etc….

    just my 10 cents worth…

  • Gigabite

    So when is AT&T going to start charging me for my unlimited talk time I usually talk to my mother for 4 to 5 hours over the phone. I wonder what they would do if I just left the phone on for like a week a one call would they charge me for going over my unlimited voice ha ha ha ha eat the poison apple and die AT&T

  • fas

    Imagine once they buy T-Mobile how they will become with their monoply.

  • Kraken

    AT&T needs a reasonable way to allow sporadic tethering use. In my case I pretty much only tether when the internet at home is down or when I travel, which comes to maybe 6 times a year. It is ridiculous for them to charge extra money every month and force you into an inferior data plan.

    With that said, I am currently traveling and tethered to my Windows 7 laptop for a few hours yesterday using the latest PDA net and level 2 hiding. No message from AT&T so far. It might be worth mentioning that I also use a VPN (on laptop) to my work network.

  • Rogers

    At least in canada rogers lets us use free hot spot at no charge.

  • Marc

    Hello friends, in my case I have jailbroken my iphone 4. I am using the Onavas app, this app is intermediary for more performance from my paln of 2G data. If I use this process it is possible that by doing so can I bypass the AT & T tracking MyWi to use on my iPhone? Well i hope!!! 🙂

  • Marc

    Sorry the app is Onavo in app store!!!

  • Terrell

    They have said I’ve tethered when I havent. After I found out they were catching people tethering I stopped but they still say I tether. I use like 5gb of data at least every month though. But I don’t get why they think I’m tethering when I’m not. It’s not just me either. My dad in another plan with AT&T has got calls saying he is tethering. Playing dumb does not work, and telling them that you use netflix all the time over 3G doesn’t either.

  • nf0rc3r

    Launch hotspot on iphone or iPad den use the wireless hotspot if “Wireless” is required to piss AT&T off.

    Scratch that. EVERYONE tether their phone on 1 June 2011 and download tons of stuff and cripple AT&T.

  • ixlr8

    This is black and white, the law calls it Bait and Switch. The way Att uses the term unlimited is the exact reason why this law was drafted. The fact that they continue to use the term unlimited is proof that they are intent on defrauding the public regardless of what the little print says. BAIT AND SWITCH!

  • Bill W

    The beauty of the free market is that you are not forced to buy this service. If you don’t like it, don’t subscribe. If you think there’s a better solution, offer it to the market. I know this seems unhelpful, but at the end of the day this is how we all subscribe … someone puts up resources to make a return on that investment, and they will maximize their return. I appreciate that, I like to invest in them in my 401k. This is an evolving market. I plan to jump to Sprint as soon as the iPhone is available on it … voting with my pocketbook.

    • famba

      That’s not the free market; that’s what is known as a Hobson’s Choice.

  • R916

    I just got off the phone with AT&T, hour long call, I was able to get ‘some’ information on how they are detecting it. he was very good at running around the question of how it is done but i was able to get him a little frustrated and he slipped in his words a bit.

    Where the Data Services Manager slipped was when he told me that the data coming back into the phone was ‘not terminating’ at the device. when i asked him to confirm what he said he wouldn’t I assume his silence is confirmation.

    They would be able to detect it probably by the MAC or IP of the device, they would still have to sniff the packets to get its src and dst it does carry some information on where the data came from(which site or service you are accessing).

    I am no programmer or hacker but i have networking experience, is there a way to spoof the phones mac address and create some kind of loopback routing which if the data is looped then it is sent to the additional device, almost like using a loopback address on a router, where if the destination is not found on that network it automatically gets sent to the loopback and/or bit bucket this way the data would appear to have terminated at the device.
    Just an Idea,

    I’ll say it again i’m not a programmer or hacker.

  • Bob

    When you use your phone as a router it injects additional information into the network packet so that it can “route” it to the correct device making the request/response (e.g. it doesn’t ‘terminate’ at the phone.

    There is no magic here, just plain-jane routing technology.

    As you might of guessed, this information is in the header of each packet and can be “sniffed”/”detected” by packet inspection (also call DPI for deep packet inspection) which isn’t easy, but it is possible. My guess is that accounts with greater-than-average data activity are added to some “hotlist” for DPI and then monitored. AT&T likely doesn’t not have the capacity to use DPI on every network device they serve, that would be a hell of a feat…but probably not too far off in the future though. 🙂

    One way to circumvent DPI is to use a VPN connection on the routed device. This then encrypts packet content information from client to server and thwarts inspection. Good luck though, most people can’t do this or dont’ know how even if they could…

  • Andy

    I’ve been tethering with MiWi for 2 years and only got the notice from AT&T after I had to replace my iphone and was locked in for another 2 years… I’m guessing they are strategic about who they send these letters to. Had I gotten it before getting a new phone I might have switched carriers.

    I wanted to confirm with Bob’s post – if I use a juniper SSL VPN (that doesn’t split traffic and sends everything to the vpn), can I assume that AT&T can’t detect tethering?

  • Sam

    How has this post not been fixed yet? NONE of the tethering apps are ABLE to use the tethering APN. That is not possible, because it would be BLOCKED by AT&T. They ALL use the Data APN. That is the only way for it to work, at all.

    This entire post is based on complete fiction.

  • zambala

    It should be against the law to circumvent the function of your device. Carriers sell data. How you access that data is non of their business. They might as well start charging more if a url contains the letter ‘b’

    They are trying to force people to buy another sim. What if carriers forced you to enter additional fixed line contracts because you had additional computers on your network?