Bypassing Three UK’s tethering block to use the iPhone Personal Hotspot

Bypassing Three UK’s tethering block to use the iPhone Personal Hotspot

Finally! It’s intricate, convoluted and definitely not worth the £5/month saving but it’s a victory none the less.

It appears Three uses layer 7 packet inspection to detect if you’re using a browser with a non-mobile user agent. Just change the damn user agent, I hear you cry. Sadly not. This does work for a few seconds before Windows sends some packets in the background that screw the whole thing up. Also, web pages show in mobile mode. During testing, I was blocked a few times. Turning Airplane mode on for a few moments and then off again cleared this.

Annoyingly, when Windows connects to a WiFi network it does some useful HTTP requests to see if you have access to the web. Once you do, it considers you fully connected. However, this lets Three know you’re tethering and they block you. The solution I have found is thus:

  1. Enable Windows firewall on your computer
  2. Use the “Windows firewall with advanced security” tool to block ALL outbound traffic from your computer. This doesn’t actually do what it says on the tin as DHCP requests and the suchlike still work
  3. Enable the personal hotspot on the iPhone and connect up to it via Wifi. Windows will say there’s “Limited connectivity”. This is ok.
  4. Browse the web using Safari on your iPhone and ensure you can flick from page to page fairly quickly. A slow connection won’t help your case here
  5. Have a VPN configured and on Standby on your computer. Ensure that, in the properties of the VPN, under Networking->IPv4->Advanced the “use default gateway on remote network” box is checked
  6. Disable the firewall rule you created. The quickest and least obtrusive way to do this is using the “Disable rule” button on the right of the firewall manager
  7. VERY QUICKLY! after this, connect up to your VPN. With any luck, you’ll connect up before Windows blabs on you. Once you’re connected, everything will go over the VPN and Three won’t be able to inspect your packets

If you fail, just try again. It’s all about getting the timing right. As I said, enable airplane mode, wait a few moments and enable it again. If you can browse the web on your phone then you’re all reset and ready to try again.

Happy to answer any questions if you leave a comment. I’m not going to hand-hold in getting or connecting to a VPN – I’m sure you can work this out yourselves 😉

12 comments

  1. Thanks for writing the article. I’m interested in finding out if this would still be the same if trying to tether an iPad to an iPhone’s hot spot?

    Any idea?

    • I’ve done it with an iPad before. The process is the same in such that you need to dial a VPN fairly quickly after connecting to the Wifi. Seems the iPad doesn’t send as much crap as Windows so it’s just a case of connecting to Wifi and then turning on the VPN quickly after.

  2. I’ve tried this method using Hamachi and Hotspot Shield VPN’s but having no luck, what VPN did you use please?

    Thanks!

  3. A very useful and well written article, thanks a lot. I saw your comment about doing this with an iPad – I presume it would be similar for a Nexus 7 or 10? (presuming of course that Three blocks those user agents at all)

    Thanks!

  4. Brilliant, although for my Win 8.1 tablet I had to leave the ‘BLOCK ALL’ rule enabled, turn on my VPN (i.e. leave it hunting trying to find a connection), disable the rule and then hey presto it worked.

    Thanks a bunch. Great info!

  5. John Winston

    I have unsuccessfully tried a different technique – connected to my VPN directly on the iPhone (via PPTP) and then connect the computer. Strangely, they are still detecting my tethering attempts.

    Does anyone have any idea how I can get OSX connected using a similar workaround?

    Cheers!

    • Sadly tethering to an iPhone connected to a VPN doesn’t push the tethered traffic over that VPN. I haven’t found a way to make it do such.

  6. Hi, this guide has been very useful to me.
    Thank You very much for that!

    However i would like to know if its possible to stay connected to the tethering without continuing the use of the vpn. (disconnect from the vpn while using tethering)

    I got this to work just once and i dont know how i actually done it.
    Do you have any idea?

  7. Why not just run a VPN client on the phone? Enable the VPN first and then enable the hotspot. All traffic will then be tunnelled over the VPN and so bypass Three’s traffic inspection.

    • Have you tried this on iPhone? It didn’t work at the time of posting this – it’d be interesting to know if it does now. I switched to Vodafone so I cannot test anymore.

    • It won’t work like that. Tethered data on iOS isn’t tunnelled through the active VPN.

      Crazy right?

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