Today I noticed that every time I pulled my T-Mobile iPhone out of my pocket and tried to use it, I couldnt use Touch ID and had to enter my passcode. I didnt give it a second thought, since I was so focused on doing what I wanted to do on my iPhone.
But then I saw the following tweet from MacRumors:
And it all started to make sense. To see if thats why I kept having to enter a passcode, I placed my iPhone on my desk and left it on. It crashed with a blue screen of death four times in 45 minutes. It also crashed while I used different apps.
The problem seems to occur with T-Mobile iPhones running different versions of iOS 8. T-Mobile has yet to officially comment on the issue, though a reddit user who talked to T-Mobile support was told that it could be a memory problem.
Posts in the Apple Support Communities say the problem may be with T-Mobiles Wi-Fi calling feature. Disabling it may stop the crashes, though re-enabling Wi-Fi calling may also re-introduce the problem.
To disable Wi-Fi calling on your T-Mobile iPhone:
Go to Settings > Phone.
In the Calls section, tap on Wi-Fi Calls.
Switch the Allow Wi-Fi Calls toggle to off.
I turned off Wi-Fi calling on my iPhone, and so far, so good.
Other possible fixes for the problem include:
Performing a hard reset (Hold down the Home and Sleep/Wake button at the same time until the Apple logo startup screen appears.)
Deleting old text messages
Performing a factory restores in iTunes
Well update this article when more information becomes available.