RTFT
I just did this yesterday!!!! You are supposed to make Apple call Verizon's Core Department when you return the phone. I couldn't get the effers to do it.
So I called Verizon and had a Verizon rep do it. The Verizon rep needs to call the Verizon Core Department to push the cancellation through so you can add a new line the next day.
How do you ask for PDI ? I did ask and CSR said no since it has contract.