4.1.1 Down-Level Experience
A client consults the configuration information specified in section 2.2.4 and sees that the outlookFlags parameter setting indicates that the client provides a down-level experience for the voice message object that it is about to display.
To provide the down-level experience, the client renders the voice message with all the functionality it would give to a typical Message object, as described in [MS-OXOMSG]. In particular, it enables the user to access the audio attachment that is included in the message by using the standard mechanism provided by the client for accessing attachments.
Having accessed the content of the audio attachment, the user uses an audio player application on his or her local computer that supports the attachment codec to play the audio content.