For the best rate program yes, you need an activated AP or the voucher. For the old fashioned call in rates, who knows. Before you didn't need it to book the rate just have it at check-in. Now we don't know because it may have changed. There may or may not be call in rates like they used to have. I have heard rumors that there will be and I hope so but won't bank on anything until I see it happen. And if they do happen I don't know if they will change it where you will need to have the AP or not.