I have been told that it would be cheaper to buy a US SIM card than to use my existing UK one when I come over for a month in October. Can I get a card that I can use anywhere in the US and make calls back home or are they 'zoned'. Last time I was over I bought one from Walmart, but it was very limited, and I couldn't call home. I do have a tri band phone that will work on US system. I have found this but don't know if it's value for money or will give me roaming coverage anywhere I need. A little help and advice would be nice, thanks.
Giok