T-Mobile is giving away free lines again, but not everyone is invited

TL;DR

• T-Mobile is rolling out a targeted “Line On Us” promotion to randomly selected customers.
• The free line is strictly a “Bring Your Own Device” (BYOD) arrangement and typically requires having at least two paid lines on the account, although additional requirements also likely apply.
• You can check eligibility by asking support to look for the “Loyalty BYOD Dec 2025” segment (ID25079) on your T-Mobile account.