Here's what works for me on the stock Sprint 6.1. Go to settings, personal, phone, services, highlight time synchronization and click the settings box, un-click the automatic sync with mobile network box. Then go to setting, system, clocks and alarms, time, and set your home time zone to GMT-8 Pacific US. I would only recommend this if you need to sync to an exchange server because it causes some other minor phone functionality issues that you have to work around, but it's the only guaranteed way that I've been able to keep the time right on my phone, and most importantly sync appointments correctly with my exchange server and Outlook, for work. These settings can also cause issues when I'm traveling out of the state. I've just become accustomed to resetting what I need to so the phone behaves the way I need it to when Im in AZ, because it works perfectly everywhere else. Its kind of a tail wagging the dog situation.