T-Mobile is offering an additional free line to postpaid customers with two or more lines. Terms apply. See details below.
Update 3/13/2023: The offer is back.
Offer Details

Get a free line if you’re a T-Mobile postpaid customer with at least two lines through the “2022 BYOD Line P1” promotion. Eligible plans include Simple Choice Plans, Magenta Max, and T-Mobile One. To get the bonus line, message T-Force via Facebook or Twitter.
Please note, you must pay a $35 fee to activate the line, and the bonus line is not eligible for the free phone promotion.
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Bottom Line
This is a super simple way to get a free line with T-Mobile. Seems like this deal comes around once a year during the holidays.
READ MORE: SEE THE BEST BANK BONUSES HERE AND THE BEST INVESTING BONUSES HERE.