T-Mobile's new promotion offers three unlimited data lines for $100

In its continuing efforts to attract more sign-ups, T-Mobile’s latest promotion offers an additional line for free for accounts with two or more lines. The offer works whether you want to add an extra phone line or a line for wearables or tablets.
The deal is available for current and new customers — the amount of data available to the free line will match up with whatever your current plan is for the other lines. If your plan does not have the same amount of data between devices, th