MC199244, Microsoft Bulletin, Published date: Jan 18, 2020
From Microsoft Corporation:
“Updated January 18, 2020: We are updating the roll-out timeline to provide the best possible experience. We apologize for any inconvenience. Microsoft Teams will soon change the control that announces when a user who is on a telephone joins or leaves a meeting.
We’ll be gradually rolling this out late March (previously mid-January).
The roll-out will be completed by mid-April (previously late January).
This message is associated with Microsoft 365 Roadmap ID 59919.
How does this affect me?
With this change, tenant admins will continue to configure the default sound made when telephone dial-in users enter or leave a meeting. However, meeting organizers can now decide whether or not to play a sound on a per-meeting basis.
What do I need to do to prepare for this change?
If you have not already done so, consider customizing the default announcement sound when telephone dial-in users enter/exit a meeting. Do so via the “Bridge Settings” on the “Conference bridges” page of Teams meeting policies in IT Pro Modern Portal.
Individual meeting organizers can turn the announcement sound on/off on a per meeting basis but they cannot select a new sound. Click the Additional information link to learn more. ”