I have an iPhone 4s and 5. Both contracts are expired and I'd like unlock them in case I decide to use them on another network. Lots of websites will do this for a fee, but can I do it myself?
They can only be used globally. The 5 is already SIM unlocked for global use.
No you cannot. Not compatible with other networks in the USA.
Or limited use. No carrier unlocks as of today for use in the USA.