For those of you owning an iPhone on the Three Mobile network you're probably be aware that tethering is blocked unless you are on the one plan. However if you have a jailbroken iPhone / iPad / iPod you can easily get around these tethering restrictions. Mobile phone operators employ number of techniques to check that the device accessing the Internet is legitimate, i.e. the device with the sim card and nothing else. Tethering can be handy in a number of situations and helps you make the most of your data allowance on your mobile plan.
Three.co.uk seem to employ a method of checking what browser is accessing the Internet as when you register a device it checks against what browser versions are available for that device.
By spoofing the browsers identify information you can get around this block.
First we need to know some browser information. From your iPhone goto Whatsmyuseragent.com
At the top where you see Your User Agent. Copy that information into NotePad exactly as it is. Now we know what Three are looking for when you browse the web.
Now for the fun part, making your iPad look like it's your iPhone when tethered.
In Cydia download "User Agent Faker" From the Big Boss Repository
Once installed head to Settings -> Scroll Down To Extensions Select Enabled to On User Agent = Custom
Paste the User Agent Information that we stored in Notes from the iPhone into that area. Of course you can always write it down or email it to yourself to make sure you're typo free.
Go into Applications and Turn On Safari
Now head back to Whatsmyuseragent.com on your iPad and check that it matches what we had on the iPhone.
Turn on tethering on your phone and bingo, tethering should now work.
This was confirmed tested as working on 21st 2013 December but Its not clear how long this workaround will last for.
We also tried using a VPN (thanks to UnoTelly for the trial) and tunnelling through but that didn't work although tunnelling was setup on the iPhone not the iPad which might explain why it didn't work.
Of course be wary of data charges, bandwidth limits. If you know of a tip to beat tethering, please write in and share.