In some cases calls placed using the Conference Add Participant API, <Refer>, and <Dial><Sip> Multidial are not being properly billed for Voice Insights Advanced Features usage. We’ll be introducing a fix for new accounts created after February 24, 2021 that will result in these call flows being billed properly. The billing behavior will not change on existing accounts.
Twilio Changelog
Additions and changes to the Twilio platform