PCS1 will be a prepaid carrier. That means you will be paying for services that you will use. whereas postpaid is you are paying for service you already used. The advantage of prepaid, is PCS1 will be able to provide you with an annual discount. You would pay 10 times the monthly rate, and you would get service for 1 year. The only disadvantage is if you were to reduce your services in the middle of your annual term, you will not receive a prorate since you already paid for services you will use. If you decide on annual discount, make sure you will be happy not only with PCS1, but your plan.
If you decide to add services however, you would receive a prorated charge that would coincide with your current plan. When your initial term date ends, you would have the option to pay annually for all of your service lines.