According to a few Nexus 4 and Nexus 5 users, Android KitKat now detects unauthorized Tethering on T-Mobile USA network.
A colleague of ours noticed that after upgrading to Android KitKat on a Nexus 4, Tethering & portable hotspot no longer works. Devices connected to the Wi-Fi hotspot are redirected to T-Mobile login page.
When an iPhone is connected to the Wi-Fi Hotspot from a Nexus 4 running Android KitKat, options to “Auto-join” and “Auto-login” appears.
The iPhone then tries to connect to a T-Mobile login page, but the page never loads.
We then use a Nexus 5 which came with Android KitKat pre-installed to create a wi-Fi hotspot. The result was the same, it forces connected devices to log in.
Another colleague of ours still has a Nexus 4 running Android Jelly Bean 4.3. The Nexus 4 is connected to T-Mobile USA network and without tethering plan. Devices connected the Wi-Fi hotspot created by the Android Jelly Bean-running Nexus 4 were not asked to log in.
We then inserted a working AT&T micro-SIM card into the Nexus 4 with Android KitKat. We had no issues using tethering through this phone.
At this point, it seems that Google has added codes in Android KitKat that detect unauthorized tethering. So far, it only affects Nexus phones (4 and 5) on T-Mobile USA network. We purchased the Nexus 4 and Nexus 5 from Google Play SIM-free and unlocked.
Is it possible that Google has added this “feature” to appease T-Mobile?
After all, Google has partnered up with T-Mobile (and Sprint) to sell Nexus 5.
We recommend users to wait from upgrading to Android KitKat on their Nexus 4.