If you are upgrading to a new iPhone, don’t forget to unlock your old one for an easier and higher resell of your old iPhone.
I’m on AT&T and totally forgot about this. I ordered the new iPhone 5 to replace my AT&T iPhone 4. AT&T actually has a page spelling out the eligibility of unlocking your iphone here. I put my request in a few days before I got my iPhone 5. However, I received and activated my iphone 5 before AT&T replied back to my unlock inquiry.
The sad news from AT&T, they only unlock your eligible iPhone ONLY if it’s still active. After calling and trying at local AT&T stores, AT&T refused to unlock my old iPhone 4 because it is no longer “active” on the AT&T network.
Reminder, unlock your old iPhone 4 or 4S first before activating your new iPhone 5!
Luckily, you can go to eBay and buy an iPhone unlock service as low as $15! All you need is to give them your IMEI number, and they set you up. You restore your phone on itunes and there it is unlocked. Feel free to use your phone internationally, sell it for $50-$100 more, or give it to friend or family to use on any carrier.