Well I've had my Halloween nightmare. I've been having reception issues with my iPhone 5. Slow LTE etc. So the AT&T chat guy he'd send me a new sim because even though it usually doesn't make a difference, it's worth a try. After sending a regular sim instead of nano, it finally came today and I changed it out. Low and behold, the new nano sim is giving TERRIBLE reception. 2 Mbps LTE!!! So I get back with chat and they said I can't switch back to my old sim. After many hours going back forth AND LOTS OF HASSLE... My AT&T original nano sim is working again. Not great reception. About 5 Mbps LTE. But still better than 2!