Microsoft offers Xbox game pass free 15-day Trial sing up for this and then if you are a tmobile customer, it stacks with the Tmobile tuesday 30day game pass code Now you have Free 45-day – Click on Manage and turn-off ‘auto-renew’ if you don’t want it to automatically renew.
http://www.xbox.com/en-US/games/xbox-game-pass
JUST CHECKED IT STACKS UP IF YOU HAVE MULTIPLE CODES WITH MULTIPLE T-MOBILE LINES