T-Mobile is handing out free upgrades to select customers over the next few days that gives many of them unlimited data for the next 2+ years at no extra charge. Another upgrade will add on an extra 1GB of data for those on 2.5GB and 5GB plans.
Customers receiving the upgrades are being notified via text message that links them to a promo page with additional details. If you are on a 10GB data plan (possibly the 10GB 4-line family plan) and receive the notification, you are being bumped up to unlimited data. If you are on the 2.5GB or 5GB plans (possibly family plans as well) from years past, you are receiving an extra 1GB per month.
It should be noted that the move to the unlimited plan does change things a bit. You still get the same amount of tethered data per month you had, but you no longer get Data Stash, since you have unlimited. That means you can’t carry over a bunch of data to later be used through tethering. With the 1GB bump up, you can use that extra 1GB for normal data or tethering.
T-Mobile hasn’t announced the promo and so far hasn’t revealed many details to press, but reports of the upgrades are everywhere. According to each promo’s landing page, the change in plan starts between September 7 and 9 and runs until February 28, 2019.
From what we can tell, this isn’t something you can call to opt-in to. If T-Mobile thinks your account deserves the upgrade, they will let you know within the next day or so.