I suggest you look into a Tracfone. You can read more about them at
TracFone Wireless | Prepaid Cell Phone | Pay As You Go | No Contract Cell Phone. One very nice feature is that there is free international long distance to many countries. The only cost for such a call is your minutes. If you're on a 15 minute call overseas, the only cost is that 15 minutes will be deducted from the minutes you have "banked" in your phone. For a list of the countries you can call, go to:
TracFone Service | TracFone Frequently Asked Questions
You can purchase a phone from Walmarts, the Tracfone.com website, OR from QVC.com or HSN.com. If you purchase from either of the last two places, you can probably find a phone that will give you
triple minutes for life. (Meaning, if you purchase a 400 minute card which costs $100 and which gives you coverage for one full year, you will actually end up with 1200 minutes for the same cost of $100).
If you purchase your phone from QVC.com or HSN.com, it will come with 1200 minutes on it, IF you choose one of the models which provides triple minutes for life. This offer (triple minutes) is NOT currently available from any retail store.
I have had very good reception anywhere I've traveled in the States from my Tracfone. No complaints whatsoever.