T-Mobile silently killed off its $10 per month 200MB data plans, a leaked document reveals. A company spokesperson verified the news with Fierce Wireless. This decision is most likely due to the growing demand for mobile data as smartphone applications continue to evolve. Grandfathered customers will not be affected by this new policy, but will need to pay full price for a device and sign up for a "Value" plan when upgrading in order to maintain their existing service plan. T-Mobile now requires its smartphone customers to have a minimum data plan of 2GB or higher, which starts at $20 per month. While this change may make sense for most smartphone users, existing customers who are light on data and heavy on savings might have a different perspective when it's time to buy a new phone. Check out an extreme closeup of T-Mobile's document after the break.