I really wanted to give this phone 4 stars, but due to an extremely aggravating bug in the OS, I cannot. I bought this phone the first week it was available in the US, to replace my existing Nokia Astound (8GB, 8MP camera, Symbian OS). Mainly I wanted a larger, crisp screen and a more customizable interface, and of course a nice camera. WP and the Nokia Lumia 925 seemed to offer all of this, and indeed it does.In retrospect, I now realize that the trouble started one night in mid-September when I was exploring the different menus of the WP OS. I stumbled upon the very last item on the App list, "Wi-Fi Calling." I had never had a cell phone that was even capable of Wi-Fi calling, so I was intrigued. There are three settings offered: "Wi-Fi Preferred", "Cellular Preferred", or "Wi-Fi Only." Actually there is a fourth setting: Wi-Fi Calling "On" or "Off". I didn''t really trust the technology yet, so changed the setting from "Wi-Fi Preferred" to "Cellular Preferred." Over the next month, a very aggravating thing began happening: I would pull out my phone to make a call, and get a "No Cellular Service" message. Or a message stating "You are in Airplane Mode". Or, "Cellular Service is turned off, do you want to turn cellular service on?" Reasonable responses to all of these messages never resulted in re-engagement of the cellular signal. In fact, I gradually discovered that the only thing that would return cellular service was to turn the phone off and then turn it back on, whereupon it immediately resumed its normal functions.I began missing phone calls from friends and relatives. Sometimes over a day would pass before I would realize my phone was no longer functioning as a phone. It was infuriating and extremely disappointing. I found myself apologizing to people who were trying to get ahold of me. Texts would not come through either, while it was locked into this Wi-Fi calling hell on earth. Naturally, the only time I got frustrated enough to take it back to the store was after I had re-booted it, and so it worked fine while I was at the store.I finally did some online searching, and actually stating my problem using ask.com revealed the answer: Choosing "Cellular Preferred" causes your phone to lock into Wi-Fi calling mode. I have turned off Wi-Fi calling completely, and plan never to use it again. It''s not worth almost having a nervous breakdown over. I want to like this phone, but right now it is in the dog house, and it''s going to have to work to earn my trust back.