Have experts configure your Twilio or Voximplant account to create a call flow and let the users join a meeting by getting the meeting ID through an IVR. The configurations will allow forwarding an incoming call to the meeting.
Create IVRs and get custom input from users, send requests to backend services and get user details and use those details to join the user to the conference.
Configure a gateway to allow users to join through SIP to the conference.