T-Mobile customers looking to expand their wireless plans might have a new opportunity to snag an extra line without paying monthly fees, but finding out if you're eligible isn't exactly straightforward.
According to The Mobile Report, the wireless carrier rolled out a "Line On Us" promotion today called "Loyalty BYOD Dec 2025," which gives certain customers a free additional line. The twist is that T-Mobile hasn't made it easy to check your eligibility—you won't find this offer in the T-Life app, so you'll need to call customer service or head to a store to see if you qualify.
To be eligible for the free line, you'll need at least two paid lines already on your account. That's been the baseline requirement for all of T-Mobile's previous free line promotions. There's also a $35 fee to activate the new line, and you must bring your own device.
Financing a phone through T-Mobile on this free line isn't allowed and could result in losing the promotion altogether. If your plan doesn't bundle in taxes and fees (like the newer Experience plans), you'll still need to pay the monthly taxes on the free line.
What makes this offer tricky is that T-Mobile hasn't clearly spelled out all the qualification rules. The carrier likely caps how many free lines you can already have on your account before becoming ineligible, but those details remain unclear. Store employees can apparently see a "Loyalty BYOD Dec 2025" tag on qualifying accounts, but regular customers have no way to check this on their own.
If you think you might be eligible, keep an eye out for notifications in the T-Life app or text messages about the offer. These types of free line promotions were common during T-Mobile's "Un-Carrier" days but have become increasingly rare over the past few years. The last similar offer launched in September and only a small group of customers qualified.
Source: The Mobile Report
