Here's what I've done successfully but requires patience. Sign up with T-Mobile ($40 or $50 plan) online and they will mail you a sim card for free (for me it was $57). I did all this online. Wait their 40 days, then chat with a rep online and request an unlock code. Once received (it took one day), call and cancel the account. This is somewhat painful as they will do everything to keep you. For me, it took about $100 to unlock, but except for the phone call, the process was painless and the cost was similar to an unlocking service which I've had no experience with but read all horror stories/posts online. I use Net10 and am now running on ATT's service, getting LTE with no issues. Good luck to you.