T-Mobile is handing out a free extra line to its customers, and it could save you $40

The offer applies to those on the new T-Mobile One plan as well as Simple Choice customers, although, as of January, new users can no longer sign up for Simple Choice. The One plan guarantees unlimited data — with the typical footnote of throttling past a 28 GB threshold — at $70 per month for the first line, $50 for the second, and $20 for each additional line thereafter. T-Mobile was already running a promotion under which customers could receive two lines for $100, after agreeing to auto pay. Coupled with the free extra line, that means one could open three lines for the same $100, as opposed to the normal price of $140.

For that deal, however, you need to be a One customer. Up until T-Mobile improved the plan last month, that came with a few unique caveats.

In its initial incarnation last fall, One reduced the quality of all streaming video to 480p, and restricted data tethering to pedestrian 3G speed. Customers could avoid these restrictions with the One Plus plan, but that came at an extra $25 per line, per month. When Verizon revived its own form of unlimited data several weeks ago, T-Mobile did away with the shortcomings to stay competitive.

One customers now receive 10 GB of LTE tethering each month, and video streaming is handled at whatever resolution is specified by the content provider. The plan also comes with international data and calling in 140 countries around the world and T-Mobile Tuesdays deals, good for the aforementioned free pizza, among such other things as movie tickets.

The carrier notes that the free line can be used for any purpose, be it another smartphone or tablet, smartwatch, or hot spot. T-Mobile says the promotion is only running for a limited time, but customers can keep the free line as long as they remain on an eligible plan and in good standing with the company.

See T-Mobile’s 3rd Line Free Offer