Teathering on an unlocked AT&T

[jameslparker2000]

I am almost sure this question has been asked so accept my apology for asking it again. I have an HTC Inspire that I unlocked and is now being used on T-Mobile network without a problem. I recently tried to use this cell as a hot spot but I get a message saying please contact AT&T. Now could I use the app Fox Fire to be able to teather or will this still be blocked from AT&T despite the fact I am not on their service?