Yeah i'm driving down the road (wife driving) and getting giddy just to send an MMS pic and i notice 3G on upper left. I'm like..wait a min.. I geeked out for a bit pulling up speedtest app. Wife, as always, rolled her eyes.
So of course i pulled up AT&T coverage map. Hasn't updated for my area. So of course i made her drive around to see how far it goes after we were done shopping. Some rural areas here and i'm pulling 2 mbps with full bars pretty much all over the place here.
The only way to find out is to be transferred to a network engineer or someone who has access to those roadmaps.
It's not an easy task to do. I found out a few towers by us were going up when I was having service issues (couldn't hold a signal with any phone, iPhone or not), they had to check a tower that was degrading in our area, and a top tier support rep was able to see when new towers were going in and where.