When I did this in the past, they prorated the old plan, then pro rated the new plan. So you should see a credit for the unused old plan's month in advance and a charge for the new plan's month in advance.
You won't get charged a full month of the old plan and a full month of the new plan.
What get's dicey is the minutes used. When they pro rate, they also look at your calls made. If you have 300 minutes a month, then halfway through decide get a different minute plan. They look at how many calls you made for the first half of the month. If it is more than 150, but still less than 300, they charge you the minute overage charge for all calls over the 150 minutes. For example, say you made 200 calls in the first 2 weeks of the plan. You will pay per minute charges for the 50 calls over 150.
If you're changing your plan to have MORE minutes, then you should always backdate it. If you're moving down in minutes, then you should future date it. This will keep you from seeing prorated charges and any overages due to funky proration of minutes due to On Demand cahnges.
The reason your first bill is prorated is because when you sign up, you're not asked to pay for anything up front. Afterwards, the only time you should see prorations on your bill will be if you do On Demand changes.Message Edited by risu on 07-13-2009 09:31 AM