I am not sure when I see “data stash” what should I think about it . I saw it on a big billboard in Manhattan Time Square. Checked in the net but nothing relevant appears. I found some info for t-mobile daya stash usage of data not used but I am not completely sure what this means.
Data Stash™ lets you roll forward your unused 4G LTE data – up to 20 GB worth in most cases – into the next month at no additional cost!
Data Stash is only available on select plans such as Simple Choice and Simple Choice with No Credit Check. If you want to stop worrying about data limits, make the switch to T-Mobile ONE™ where you'll get unlimited talk, unlimited text, and unlimited 4G LTE data on your smartphone. Learn more about T-Mobile ONE.