Will Tmobile Fav5 Plan work on a non-compatible fav5 cell phone?

Im currently on a tmobile fav5 plan but i broke my fav5 cell phone and I just want to buy a regular unlocked cellphone because those fav5 phones are a little too expensive. Will fav5 still work if I use an unlocked phone? I've heard some people say that it works and some people says it doesn't so im confused. Please answer only if you work for tmobile, or have talked to a tmobile representative about it, or is currently doing it. thanks!