In relation to mobile phones - it means the handset is no longer tied to the original network it was sold to. When you buy a brand-new mobile, almost always it's 'locked' to a specific network - meaning it will only accept SIM cards from the samenetwork. However - it's possible to unlock it - so it will accept SIM cards from any network - not just the original one it was locked to.
In the United States, when you purchase a phone from a cell phone carrier (like AT&T or Verizon) it often has included software/hardware elements that restrict the phone so that it will only work on that one carrier.
You can 'unlock' some phones so that you can use them on other carriers, so for example some people will purchase an iPhone but want to use it on the T-mobile network instead of AT&T's network. Right now you can only do this with an 'unlocked' phone.
Yes, wether the iPhone is legally unlocked or jailbroken-unlocked.
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.
eBay or Craigslist
yes. once an iphone is universally unlocked it will work.
Yes, you can now buy the iPhone 4S unlocked direct from the Apple website
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
No!
Yes
No it has to be unlocked