It seems like in certain areas, I pull out my Sprint iPhone 5, and I see it say "Extended" on the carrier portion of the display. I know this area has great signal from Sprint. It seems that in certain areas around my neighborhood, despite having a decent enough Sprint signal, it will roam on Verizon when it's in my pocket? I know this sounds weird, but it really is. Could it be that Verizon has 700Mhz or lower bands that improve "in building" therefore, "In pocket" coverage? The minute I pull the phone out of my pocket, it'll change from Extended to Sprint after a few seconds of holding the phone outside of my pocket. I know the problem is not with Sprint, as I have an iPhone 4 on T-Mobile as well, and when I pull out the phone from my pocket, sometimes I see that I have no service, in an area that I know has service. I just don't want to be missing calls just because my phone is in my pocket, being carried around like I have carried any other phone.