

Affected users are experiencing a split second blue screen that's followed by their devices restarting, and it appears most people who are seeing issues are T-Mobile customers that began having problems last night or this morning.
Known devices with problems include the iPhone 6 Plus, the iPhone 6, and the iPhone 5s, with restarts happening at 10 to 30 minute intervals. Multiple versions of iOS 8 appear to be affected, including iOS 8.1 and iOS 8.3.
It is not clear if T-Mobile recently pushed a carrier update that's causing the problem, but a reddit user who spoke with T-Mobile's support staff said that he got the impression that T-Mobile believes a memory problem might be the cause of the restarts. "The sense I got from the technician is that a) they suspect memory problems, and b) they're getting a lot of calls about it," he wrote.Hey guys. So this morning my iPhone 6 (4 months old) started just randomly restarting itself every 20-30 minutes or so. I wasn't even using it most of the time, it was in my pocket at work (could tell because of lock screen that indicated I needed to enter my pin after a restart as opposed to finger ID). At one point I was texting my SO about it, the screen turned blue for maybe 2 seconds and it restarted.
Some users have had success putting a stop to the restarts with a hard reset, and that's the solution that T-Mobile is recommending to customers who call in. If that doesn't work, T-Mobile is instructing customers to clear out their old text messages and do a factory restore via iTunes.
Update: Many users are reporting that disabling Wi-Fi Calling fixes the issue.
Article Link: T-Mobile iPhone Users Seeing Frequent Random Restarts and Blue Screens