As of last week, Apple now offers the iPhone 4 in three flavors: the AT&T iPhone 4, the Verizon iPhone 4, and the unlocked iPhone 4. The unlocked iPhone 4 can be used with phone service from any GSM carrier, and you can install apps not available from the App Store.
People have been unlocking iPhones for years, but an officially unlocked iPhone means that the device won’t risk being “locked out” from iPhone operating system updates.
Should you consider buying the unlocked iPhone?
The answer is “yes” if you plan on traveling overseas or if you think you will need to change GSM carrier and don’t want to be stuck in a two-year contract with AT&T or Verizon. You can find out more from this CNET article by Josh Lowensohn.
Karen Anderson
iPhone 4 Tips 
Now that it’s been unlocked it’ll be so much easier for me! In the past, I’ve needed to carry my iphone and then another regular phone, but now I can carry just my iphone! Also, during my last trip to the UK, I was able to finally test out this new SIM card – something called a global SIM, not really sure – from Talafone… it saved me TONS! I was worried about the roaming charges and everything and then I found this company through a friend of mine and it offers one flat rate from anywhere in the world to anywhere in the world – ONLY $0.50!!
Anyways, just thought that I’d share that little tidbit of information – maybe it’ll help out other travelers as well. The website is here, http://www.talafone.com if you want to check out 🙂