For some reason, I can't seem to find Samsung 807 model, so this is what I'll say if you want to buy that phone off eBay. If you're thinking of going with Cingular, get a phone with 850 and 1900 band support.
If you buy a Cingular branded phone, it doesn't have to be unlocked (since Cingular branded phones are set to accept Cingular SIM cards by default) and it probably already has 850 band support (if it's a reasonably recent phone anyway).
If it's NOT cingular branded, then it's especially important that you make sure the phone is unlocked (or you might have to unlock it yourself, and some phones are harder to unlock!). Also make sure that the phone supports the 850 band along with 1900 band (FYI: 900 band is NOT the same as 850!). You can technically get by with 1900 band only phone, but you'll immediately notice horrible reception, lower bars, etc. (Cingular network relies on 850 quite extensively)
Unlocking GSM cell phones to the best of my knowledge is perfectly legal in the United States and in most countries in Europe. BTW, Unlocking a GSM phone means simply removing the SIM card restriction (e.g.: The phone will accept only a certain kind of SIM card, perhaps one from a certain company. Once you unlock the phone, the phone will take in whatever SIM card you put in)
Hope this helps...
