Can I do this... (TMobile phone on additional line)

[LaloG]

So I'm new to T-Mobile and they started an offer today that gives you a free iPhone 7 with trade in or adding a line. Now I recently purchased an iPhone 7 but refused delivery figuring I could just suck it up for a few more months and wait for the next iPhone but a free iPhone 7 is hard to pass up. Can I theoretically add a free 3rd line (yes this qualifies), trade in my 6, and put in my current SIM card in the new phone and just hold on to the new SIM card doing nothing?

 

[Applejuiced]

Yes, as long as you pay the bill you don't have to use that line with that phone. You can switch it and use on a different line.