If you own an iPhone 6, iPhone 6 Plus, or iPhone SE and use it on T-Mobile, don't update to iOS 10. Not yet, anyway. The word comes straight from the magenta carrier itself, and its outspoken CEO John Legere. The reason is that after you update your device it may in fact lose connection to T-Mobile's network. That's obviously not something anyone would want, so the advice is to refrain from making the jump to iOS 10 until the underlying issue gets fixed. Apple is working to resolve the problem, and the fix should be out within 48 hours - so you don't have to wait too long to be able to...
Source: http://www.gsmarena.com/tmobile_iphone_6_6_plus_and_se_users_shouldnt_install_ios_10_yet-news-20533.php
