During the port-away process from Twilio, we ensure service continuity in line with general telecom industry practices. Here’s how it works:

• Ongoing Service: Twilio provides ongoing voice and SMS service to numbers being ported away for ten days after the scheduled port date. This overlapping coverage minimizes the likelihood of downtime.
• New Carrier Responsibility: After the ten-day period, your new carrier is responsible for providing voice and SMS service. As long as your new carrier executes the port properly and can provide both voice and SMS service, you should experience no downtime in connection with a port-away request.

Apart from US toll free numbers, Twilio provides ongoing voice and sms service to the numbers until Twilio receives the port completion confirmation from their current carrier. Twilio will not release the numbers on its own to prevent any outages; instead, the Twilio team will wait for the confirmation from its carrier partner that the port-out is successful. Customers will also receive a notification regarding the same, and the Twilio console allows you to check the port out status. 

In terms of US toll-free numbers, Twilio waits for the customer's approval confirmation for 24 hrs; if no response is received, then the port will be rejected and if the customer approves the port request, Twilio confirms approval with the gaining carrier. And releases the number from its inventory after 10 days. 

This approach ensures a smooth transition and continuity of service during the porting process.