You can visit apple.com or visit a local apple store for unlocked iPhone.
Unless its an iPhone then it would be no.
You can check to see if your iPhone is unlocked by inserting a SIM from a different service provider and try to make a call, if its successful. Your iPhone is unlocked.
Yes, you can now buy the iPhone 4S unlocked direct from the Apple website
yes. once an iphone is universally unlocked it will work.
There are several providers of unlocking services for iPhones - both on location in Orlando, but if you don't have an unlocked iPhone yet, you could check out unlocked iphones on www.unlockediphones.net.
600
Yes
No!
No it has to be unlocked
Yes, you need an unlocked & Jailbroken iPhone. Which isn't cheap.
The iphone will be restored using the last backup so your info will be saved and it will still be unlocked.