I have them for my work phone (I don't choose the service) and generally my wife's phone on AT&T towers is far and away a better performer. We both tend to get phone calls, but mobile data sucks on T-Mobile in places like Bear Lake, St George, and Moab. Driving the I-15 corridor to CA there were plenty of dead spots for me where my wife had a fine signal. If you want mobile data to really work wherever you are, stick to Verizon or AT&T.