According to information on Cellmapper.net, the nearby tower out on US-70/25 has bands 2 & 4 (PCS & AWS). Do you have Internet service at home (e.g. DSL, cable, etc)? If so you might benefit from either using WiFi Calling or a CellSpot femto-cell.
Update: T-Mobile does not have a 700 MHz license in Madison Co and it appears that there are at least two TV stations that would need to be rechanneled before they can use their 600 MHz license there.
Thanks! Cellmapper android app and web site was exactly what I was looking for. By loading the app on my phone I was able to verify the tower that I'm hitting, levels, and frequency.