The billing cycle for port requests begins as soon as we are able to schedule your port date. Typically, port dates are scheduled roughly 7 days prior to the completion of the port itself. Consequently, Twilio will start billing you a monthly fee for your ported phone numbers approximately 7 days before the port date.
Once billing begins, these phone numbers will be billed monthly on the same day of the month that the port date was scheduled or on the last day of the month if that specific day does not occur in a particular month (e.g., February 28 if the port was originally scheduled on January 31).
It's important to note that for the period from when you submit your port request until we are able to schedule a port date, you will not be billed for the phone numbers. Additionally, Twilio does not charge for porting services for US numbers.
Once the porting is completed and the number is active with us, the billing cycle starts accordingly.