Default Sim Unlock?

So i have been looking this up for a day now and I can't find anything helpful or that works. I have a att s4 active. I want to sim unlock it because its pretty much useless to me right now. I just got this phone and the guy said he got the sim unlock code from att but we have to wait 48 hours for it to go though and now he isn't texting me back at all. I don't have the money for a unlock code and i just need this unlocked asap! does any one know any working methods?