Hello, Philip
I am Igor, an Independent Advisor and I will be glad to help you with this question.
When someone leaves a voicemail message for a user in your organization, the voicemail is delivered to the user's mailbox as an email message attachment. Using mail flow rules to apply message encryption, you can prevent those voicemail messages from being forwarded to other recipients. When you enable protected voicemail, users can listen to protected voicemail messages by calling into their voicemail mailbox or by opening the message in Outlook, Outlook on the web, or in Outlook for Android or iOS. Protected voicemail messages can't be opened in Skype for Business or Microsoft Teams.
Go to
https://admin.microsoft.com and sign in using an account with global administrator permissions.
Select Show all and then go to Admin centers > Exchange.
In the Exchange Admin Center, select Mail flow > Rules.
https://docs.microsoft.com/en-us/microsoftteams...
Hope it helps!
Best Regards
