With T-Mobile, I could sit in my living room, turn the wrong way and lose my signal. Had to go outside many times to complete a call. Couildn't get my voice mails when out of state and had to wait until I got back into Georgia, even though I had free nationwide roaming. Like Roger, I often didn't get a voice mail notice for up to a week. When I had phone problems, many T-Mobile stores wouldn't help because they only SOLD phones.
I switched to Straight Talk from Wal-Mart, with unlimited text and talk. $47.50 a month. I've only encountered a few spots, even in the mountains, where I didn't have a signal. AND NO CONTRACTS.