T-Mobile subscribers may want to keep an eye on incoming text messages over the coming days. That's because the disruptive carrier is sending invitations out to select customers with an offer to upgrade their data package to unlimited 4G LTE data free of charge for the remainder of 2015.

The promotional text provides lucky recipients with a link to this landing page with all of the details. There's no extra cost and no action required; not much to complain about there.

T-Mobile does note that users will see their Data Stash and starter stash (rollover data) disappear but with unlimited data, there's obviously no need for rollover data. The free data offering starts on April 1 and runs through the end of the year. If for some reason, a user wishes to stick with their current plan, they can simply text "STASH" to 1508 by March 17.

It's worth pointing out that the offer is just for unlimited data and doesn't include other benefits that a customer would get if they were signed up for the provider's highest unlimited 4G LTE Simple Choice plan. That plan also includes access to Rhapsody unRadio and a higher data allowance for tethering.

TMONews reached out to T-Mobile for more information but there's been no reply as of writing. What they did learn (from a source that is familiar with the promotion) is that the company was simply hoping to surprise a small percentage of customers they believed would benefit from unlimited data.