The line was with 24 months (2 years) agreement with the installment billing. But I was told that I could do the leasing option for 12,24 or 30 months.
With the installment billing I was told that I would have to pay the monthly installment price for the phone each month and I'll be credited for the actual plan per month. So I think in your case the leasing option for a year might be your best option. I would call your local store to verify that the 12 month leasing option can be used.
Sent from my iPhone 6+