jhawkkw
Chinchillin'
It might work in an AT&T or international phone. Neither of my original AT&T Notes were identified on the my t-mobile page when used on a phone plan. I never tried them with the sim from my T-Mobile 7.0+ as the thirty dollar phone plan is just a better value than any T-Mobile prepaid tablet plan.
At this point in time, from my understanding, it's only available on certain tablets (or at least that's what their website seems to infer). Also, it seems that you can't set it up yourself currently since the ability to is not on their website, so getting it activated on a phone seems impossible because a store rep would obviously see it's not a tablet.