Originally Posted by Mr Ian B
Just buy an unlock code and then your friend or relative can put in a sim card for another carrier.
I don't think that is 100% true. Cariers now share blacklist. I had tmobile phone I bought off craigs list that was blacklisted shortly after I bought it. Even after I unlocked it, it would still not work on tmobile or ATT. I was able to modify the IMEI on the phone, only then was I able to use it, kinda.
Phone: I can never just pick one..
LG G2, LG F3, iPhone 5, iPhone 4s, iPhone 4, iPhone 3GS, iPhone 3, iPhone 2G, LG Optimus G, Nexus 4, HTC One, HTC One S (x3), Galaxy Note 2 Verizon (2x), Galaxy Note 2 International, HTC 8X, Nexus, Galaxy S3, HTC One X, HTC Rezound, Droid DNA, LG Optimus V, HTC Sensation, HTC MyTouch 3G, HTC Hero, Palm Pre (ya, I said it)