What's the easiest and cheapest/free way to unlock a Cricket Moto E 1st gen?

[AC Question]

I bought it from store new in box. The phone has never been activated. Cricket says they can unlock after 6 months on their service, but I want to use my Att sim from my current account. Att says it's possible but I need the phone unlocked.
Thanks.

 

[wlonsdale]

Cellunlockerdotnet. I use them all the time and they're fast