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Some of the more popular promotions among knowledgeable customers is the “Line On Us” promo.
Back in the glory days of Un-Carrier, T-Mobile offered a ton of free lines to customers, but for the past few years, they’ve been few and far between (and with restrictions). The latest one was back in September, and very few customers qualified.
We thought they might be gone for good, but it seems T-Mobile has decided to surprise us with one more.
Loyalty BYOD Dec 2025
According to multiple sources, a new “Line On Us” promotion is beginning today for select customers. This free line would be an additional line on your existing account, and would require no additional purchases (other than the $35 Device Connection Charge). If you’re on a plan that doesn’t include taxes and fees (like the Experience plans), you’ll also end up paying taxes on that free line monthly.
What customers qualify, you may ask? As with many other promos of this type, no one truly knows.
What we do know for sure is that you must have at least 2 paid lines on your account. This is a standard requirement for free line promos, and has been required for every free line ever given on T-Mobile.
As for other requirements, well, we’re not entirely sure. It’s likely that, as with past promos, there are limits to how many free lines you can already have on your account. However, this time around, we don’t know for sure what that limit will be.
If you do manage to qualify, you’ll see an eligibility notice in the T-Life app, as shown below, and you may even receive a text message advertising the promo.
Either way, if your account is eligible, it will have a special “segment” on the account, which only employees can check, called “Loyalty BYOD Dec 2025”.
Of course, if you do qualify and choose to take advantage of the free line, be aware that it’s BYOD-only (bring your own device), which means you cannot finance a phone through T-Mobile on that line. In fact, we’ve seen others who have tried adding a financed device to a free line in the past and ended up losing the free line promo.
Update: Weirdly, it appears this particular Line On Us isn’t available via T-Life at all, and can only be claimed via support or in-store. That’s a bit weird given how hard T-Mobile has been pushing T-Life lately, but whatever.
The new “Line On Us”, with a promo ID of ID250791, begins today. Keep an eye out for a text (maybe) more info, and if we learn more, we’ll be sure to update this post.
