Another interesting method I've heard that at least avoids minute usage is to get an Android phone on a cell phone plan that gives you unlimited calling to 1 or more numbers of your choice, like T-Mobile's myfaves plan. You then set your Google Voice number as one of those numbers, and as long as you're always sending or receiving through that number, you'll never run out of minutes.

Because I'm someone who does talk on the phone quite a bit (90% of which is supporting clients and calling support lines), I can't tell you how much of a relief it was to simply give in to T-Mobile and pay for their $50/month unlimited calling plan. I love not having to worry about minutes. I know you don't make many calls Bitt, but this is my experience from the other end of the spectrum. It might be $50 a month, but because that is so much lower than the competition, I still feel like I'm getting away with something.