Anyway, some of you may know about the free unlock method posted by owl74 in the Note II forum (link: http://forum.xda-developers.com/showpost.php?p=34661189, has screenshots). This turned out to work for the SGSIII, the SGSII and SGSII Skyrocket. Well this post is to verify that IT WORKS FOR THE RELAY 4G TOO!
Before proceeding: do this at your own risk. There is no guarantee it will work for you. You MUST be running a stock ROM with a stock modem. I am using the UVMA2 stock ROM with the UVMA2 modem on T-Mobile USA.
Read ALL directions first before trying this out.
This was ONLY tested on MY phone, with the UVMA2 update and modem, on T-Mobile USA.
Without further ado, here are the complete steps toward unlocking the Relay 4G (Thanks again to OP owl47):
*NOTE:* Never use the "back" button. There is an option when pressing the menu button to go back.
- First, dial Code:
- Hit option  UMTS
- Hit option  DEBUG SCREEN
- Hit option  PHONE CONTROL
- Hit option  NETWORK LOCK
- Hit option  PERSO SHA256 OFF
- WAIT exactly 30 seconds.
- Hit the menu button and select the "Back" option.
- Hit option  NW LOCK NV DATA INITIALLIZ
- WAIT exactly 60 seconds
- There will be no prompt, but reboot your phone. It should now be unlocked.
Verify that your phone is unlocked by using a SIM card from another network. I tested it using my wife's AT&T SIM card and it connected successfully.
The prompts and the menu for the Relay 4G is a bit different from the other phones, but the screenshots provided in the original link above should serve as a rough guide for what you might see. I personally never saw the 'PERSO_NV_INIT is SUCCESSFUL' prompt, but it still worked for me.
Your mileage may vary. If someone is brave enough to give it a try on earlier versions of stock ROMs, be my guest.
For a rooted UVMA2 rom, gee one posted a link to his FTP site where he is hosting a copy of the rooted rom (should be CWM flashable):
Post your success/failure below!