Line 2 is a new line and requires monthly device payments for 24 months.
The bill reflects both device payments and a bill credit for one line over 24 months equal to the amount off to get the device for free or reduced in cost. The bill credit starts one to two billing cycles after purchase and includes additional credits for the previous payments.
If you pay off the device payment agreement balance early, then you forfeit any unpaid credits.
For example, this is the current promotion for the Samsung Galaxy S10 models that is almost a full BOGO deal. The second device is only partially discounted at $750 off instead of "free" after bill credits.
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