For phone numbers that are porting to Twilio’s platform, the billing cycle begins as soon as a port date is scheduled. Normally, a port date is scheduled roughly 7 days before the number is expected to port to Twilio. If you attempt to cancel a port during this time, you may be charged for one month of service. In order to avoid the possibility of fees, it’s best to submit cancellation requests as soon after the initial port request as possible.