The problem with that is where I am at, there's typically no voice coverage, either. There are huge areas in rural Western, WA that you can't get a cell signal because there's hills and mountains between you and any towers. What's even more funny is that when I'm at home, I get service from one tower that is 40 miles away. If the power goes out, there's no other tower nearby to take the calls, and there's no plan for any of the telco's to put one in. Heck, the one tower that feeds 4 towns (one having a population of 4 - 5000) is typically down for a total of about a month out of the year. Instead of putting a little money into upgrading it and it's capacity, they simply put money into fixing an EDGE tower, where a 3G or LTE tower would make more sense.
The problem isn't that they can't upgrade the tower, it's that they don't want to because the other company that uses their bands would also reap the benefits of the newer tower and access due to sharing agreements. For them, keeping us on limited voice + EDGE is the best way to go, I guess.