When I talked to two T-Mobile customer service people this morning, they both said that in order to use the 200MB free for life plan, you had to also have a voice or mobile data plan you were paying for for the same or some other device. I did not think that was right so I hunted down this Q & A question from this press release on 11/5/2013:
http://newsroom.t-mobile.com/phoenix.zhtml?c=251624&p=irol-newsarticle&ID=1872166
Q. If I buy a tablet device outright, do I need a service payment relationship with T-Mobile?
A. No. Bring it in to us or buy it in full from us and we'll get you on the network where you'll get 200MB of free data (plus SIM card purchase), every month, for as long as you own your device.
When I pointed this out to the second customer support rep, she backed off and said I did not need another voice or data plan.