iPhone 5C network unlock?

[Lyris]

Hey forumers,
My girlfriend got an iPhone 5c from eBay and the damn thing is locked to some other cell network. She's trying to use it on AT&T, but no dice.
Googling around, it doesn't seem like there is any sensible answer to this question, so I'll ask here: how does one go about removing this restriction? Without "jailbreaking"/using hacked firmware?

[wod]

I think the only way is to find out the network the phone was originally on and they request an unlock from apple.

Otherwise jail break will remove the network lock but will be wiped off if you have reset the phone etc