Your billing date is determined by the activation of your phone number.
Port to Billing Date
If you port in a number, you are only charged when your port completes. On the day your number transfers and activates to your account, you are billed for your first month and the one-time setup fee.
New Number Billing Date
If you purchase a new number, you are charged when that number has activated.
On the day your number activates, you are billed for your first month and the one-time setup fee.
The activation day will now be your monthly billing date. (e.g. if your number transfers on October 10, then every month on the 10th, you will be billed for that month of service).
Can I change my billing date?
Note that there is not a way to change this in your account but you can send a request to customer service and we can accommodate this request for you.