Editors' Note: This article was originally updated Nov. 16, and has been updated to reflect that T-Mobile is extending this deal through Nov. 22.
T-Mobile frequently dangles a free fourth line of data to get families to sign up for its wireless service. The wireless carrier is doubling up its efforts through Tuesday, with an offer that adds two additional lines of data to any two-line plan at no extra cost.
T-Mobile's offer of two free lines of data went into effect on Friday, Nov. 18. Originally slated to end Sunday Nov. 20, T-Mobile now says it's extending the deal through Tuesday, Nov. 22 for both new customers as well existing T-Mobile subscribers who pay for two lines of data.
The savings can be quite substantial with this offer. A single line of unlimited data on T-Mobile costs $70 a month, with a second line running you $50; additional lines typically go for $20 each. Essentially, then, T-Mobile's offer to give you those two extra lines for free will save a family of four $40 each month.
Those free lines of data will still wind up on your monthly bill, at least initially. In the fine print for its offer, T-Mobile says that you'll get the two lines free in the form of bill credits and that it can take up to two bill cycles for those credits to kick in.
T-Mobile recently streamlined its data plans to focus on unlimited data on top of unlimited talk and text. But there's a big caveat you should know about first: under the T-Mobile One plan, video streaming is limited to 480p resolution. T-Mobile says that's DVD-quality resolution and contends that it looks just fine on a smartphone-sized screen. If you disagree, you'll either have to pay an additional $25 a month per line for T-Mobile One Plus, which lets you stream video at full resolution. T-Mobile also offers 24-hour HD streaming passes for $3 if you only need high-resolution streaming on occasion.
But since announcing this deal, T-Mobile has since clarified that you're not necessarily limited to the carrier's unlimited plan if you want to add free lines of data. Current customers on T-Mobile's Simple Choice, which offer monthly allotments of data in addition to unlimited talk and text, can add two free lines to their current plan (so long as they already have two paid lines). And new customers who activate at one of T-Mobile's retail stores can opt for Simple Choice plans as well.
T-Mobile is also planning a series of deals for Black Friday, including a free Galaxy S7 when you trade in a Galaxy S6 or Galaxy Note 5 and agree to 24 months of service or a free Gear VR headset with a $50 Oculus app store gift card for anyone who buys an S7 or S7 Edge. T-Mobile had offered Samsung Tab E or LG Gpad X tablets for just the sales tax when you agree to 24 months of service, but those deals ended on Nov. 20; instead, T-Mobile is now offering an Alcatel Pop 7 LTE tablet for just the sales tax after 24 months of bill credits while supplies last.