2.2.2 Voice Message
Voice messages and fax messages are Message objects that follow specific conventions, including:
The value of the PidTagMessageClass property ([MS-OXOMSG] section 126.96.36.199) on the Message object, as specified in section 188.8.131.52.
The format and order of voice message and fax attachments, as specified in section 184.108.40.206 and section 220.127.116.11.
The use by the client of the PidNameAudioNotes property (section 18.104.22.168) for storing user annotations, as specified in section 22.214.171.124.
The optional inclusion of speech-to-text data in the PidNameAutomaticSpeechRecognitionData property (section 126.96.36.199), as specified in section 188.8.131.52.