When a user calls the a Twilio phone number connected to this Twilio Function their number will be checked against the list of valid callers. If the number is valid, they'll get connected to the conference line. For the conference to start the number that's specified as Moderator needs to join the conference.

Note: This implementation does not verify that the phone number of the caller hasn't been spoofed. For a more secure version check out Conference Line with Phone Verification.