Refer: http://pocketnow.com/2014/01/20/kitkat-broke-t-mobile-tethering
KitKat broke T-Mobile tethering
While using my Nexus 4 running various versions of Android, I never had a problem tethering my tablet to my phone, but after I got my Nexus 5 I noticed that whenever I’d try to tether, the tethered device would redirect to a “sign up for tethering page” hosted by T-Mobile. That’s not very cool, but since I’d recently upgraded my 5GB plan to T-Mobile’s “unlimited” plan, I figured it was no longer allowed. Out of curiosity, I bounced the problem off several of my friends across the country, some who still had the 5GB data plans (without any mention of tethering restrictions in their contracts). They, too, were unable to tether in a post-KitKat world — regardless of which device they were trying to tether to.
Since the old plans didn’t prohibit tethering, and are limited to a specific amount of traffic, it can be argued that it doesn’t matter where the data comes from (the device or something tethered to it). Therefore, re-enabling the tethering should be perfectly okay to do. Of course, I’m not a lawyer, nor am I dispensing with legal advice or telling you how to break any rules. I’ll let you decide for yourself if this hack is appropriate for your particular situation.
How to re-enable tethering
KitKat introduced a new “flag” which the OS sends along to the carrier to indicate whether the data is from a tethered device rather than from the device itself. So far it looks like T-Mobile is the only carrier that is using that flag.
To change things back to the way they were pre-KitKat, all one has to do is change that flag. Doing so isn’t difficult, but it does require that you have a rooted device. If you’re game, here are the steps you’ll need to take:
- Rooting and messing around with system files could render your device useless, so by continuing you’re assuming that risk
- Also, since this involves working around a carrier setting, you also need to make sure that your plan doesn’t prohibit you to tether (Note: your plan doesn’t have specifically allow you to tether, it just has to not prohibit doing so)
- Back up anything that you don’t want to lose
- OEM Unlock your device (if you have not done so already)
- Root your device (if you have not done so already)
- Using a root file explorer, navigate to /data/data/com.android.providers.settings/databases/ and make a copy of settings.db (this step is optional, but you’ll want a copy, just in case you need to restore it later)
- Install and open a SQL editor and grant it root access when prompted (I purchased SQLite Editor from the Play Store for a few bucks and it’s very easy to use)
- Tap the APPS tab and then “Settings Storage”
- Tap on settings.db then global
- Tap on the + symbol to add a new key/value pair
- In the name field type in tether_dun_required
- In the value field type in 0 (zero)
- Tap Save
- Open the Android system Settings
- Under WIRELESS & NETWORKS tap More…
- Tap Mobile networks then APNs
- Make sure your T-Mobile configuration is selected (mine is T-Mobile GPRS), then tap on it
- Make sure your APN protocol and APN roaming protocol are both set to IPv4 (it doesn’t look like tethering works with IPv6 yet)
- Make sure your APN is set to fast.t-mobile.com
- Reboot
- Enjoy your tethering!
The steps seem more difficult than they are, and I’m disappointed that Google and T-Mobile are forcing this restriction on people to whom it doesn’t apply. Nonetheless, with a little bit of know-how and rooted device, you can “fix” that oversight.
