It is the responsibility of the project owner to adhere to the local laws and regulations regarding "Do Not Call" lists. Twilio does not handle these lists and we do not refuse attempts to call and send messages to these phone numbers.
If you try to send an SMS message to a phone number on a "Do Not Call" list, Twilio will attempt to send these messages. Messages may show up in your logs as "Sent". However, if the 'To' number is on a Do Not Call list, these messages may be filtered by the recipient's carrier.
We recommend that the project owner maintain and update their own calling and SMS messaging lists so that it is up to date with the phone numbers on the "Do Not Call" lists.