If you do not want to receive any phone calls on your Twilio phone number, you must remove the Voice Request URL from your Twilio number and leave that field blank. Without a Voice Request URL, this phone number is considered 'out of service' for inbound calls. You will not be charged for any incoming calls nor will these calls be received and logged in your account.
To reject phone calls coming from specific phone numbers, use the <Reject> verb. As long as
<Reject> is the first verb in your response to the call, Twilio will not answer the call. If any other TwiML verbs are used before
<Reject>, the call will be answered by your application and your account will be billed. Here's an example of how you can implement this functionality.