@Brewster
I understand that unexpected charges can be concerning. With Twilio, you are typically charged for the time a call is initiated until it is ended, even if the call isn't picked up. This is because Twilio still uses telephony resources to handle and route the call attempt. However, the exact billing details can vary based on the type of number dialed and the specifics of your Twilio plan.
If you believe there has been a billing error or if you have further questions about how calls are charged, I would recommend reaching out to Twilio's support directly for a detailed explanation and to address any discrepancies. They will be able to provide the most accurate information based on your account activity.