I have three lines and put the two phones on two of my current lines. Maybe I missed it but I didn't read anything in the seven pages of terms and conditions about needing to add a line. Now, obviously TMobile will not let you put more than one phone on a line, so if you don't have two free lines already then that will be a problem.
I have attached paragraph three of the terms and conditions where it states in a single transaction. When you click the terms and conditions link it will bring up a seven page pdf and this is paragraph three.
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