Back in February of this year Microsoft announced the retirement of Exchange UM services in favour of Cloud voicemail that has been around for a while. Both of these services use your Exchange mailbox to store voicemail messages while Exchange UM had some nicer UI elements for playing and previewing voicemail messages and some different features, cloud voicemail just comes as a message with a standard Mp3 attachment in the Mailbox. If your using Cloud voicemail with Microsoft teams you do get a play control like also the Cloud Voicemail service has an Audio transcription service which is reasonably accurate. Accessing Voice Mails programmatically Accessing these voice messages is pretty easy they are all just messages in your mailbox (usually the Inbox but they can have been moved to other folders) that have a MessageClass of IPM.Note.Microsoft.Voicemail.UM.CA ref https://docs.microsoft.com/en-us/openspecs/exchange_server_protocols/ms-oxoum/102b3a8b-1aad-4f29-90a3-998262d9fa2
Pushing the Envelope in Messaging and Office 365 Development