I think many read the "21 Hours Talk Time" thing and are under the impression that this phone will last 21 hours of constant use. Best I have done is 8 hours of solid use meaning the phone screen was on for 8 solid hours streaming video on Netflix and Youtube, playing games, texting, Facebook, Twitter, etc. on 4G with no WIFI connection and a fairly weak 4G signal to boot. I'll take that any day. I think to that the strength of the 4 G signal plays a major effect on battery life on 4G. If I get a really weak signal the phone gets pretty hot and uses battery a lot faster. I have been thinking of just switching mine to 3G only as I can stream video in my area with no buffering on 3G so don't see any advantage to 4G unless I was trying to download a large file which I rarely do. I really don't think the "battery level" readings are all that accurate at times either. I wanted to run mine down till it shut off last night. It hit red and said connect a charger. It took me well over an hour, close to two hours of constant use with everything turned on I could imagine to get the thing to shut off. With mild to moderate use, I could go a couple days without a charge and have once when I plugged the charger in but didn't get it pushed in all the way I guess and phone didn't charge overnight. I am just pleased that I don't have to carry a charger with me to work anymore and can get through a whole 12 hour shift and to home with plenty a charge left. Mine is normally at around 30-35% when I plug it in to charge after a 12 hour shift which I use the phone a lot during my down time.