Why do some used cell phones (same service provider) work in your area but some don't?

Question

I'm looking at used cell phones on eBay and I'm wondering why some say they will work in my area and some won't even though they are the same service provider (ie. 2 identical phones, both from Verizon, but I'm in CA and the phone from NY will work but the one from WI won't...) What gives?

Oh, and what does 'unlocked' mean in reagrds to cell phones and why is that important when buyinga used cell phone?

Answer 1

I'm not really sure about the original question about similar phones not working for you in your area, but an unlocked phone is one that is no longer "locked" by a particular provider (whomever it was originally bought from). So the good thing about that is if say the person you are buying it from bought it from Cingular and your buying it but use Verizon then you will be able to do so. If it's a locked phone, you can only use it with the original service provider.