220.127.116.11 Creating a Voice Message
The server MUST add the audio content for a voice message as a file attachment on the message, in accordance with the procedures for attachment handling, as specified in [MS-OXCMSG] section 18.104.22.168. The server MUST set the PidTagAttachLongFilename property ([MS-OXCMSG] section 22.214.171.124) and the PidTagAttachMimeTag property ([MS-OXCMSG] section 126.96.36.199) as specified in section 188.8.131.52.
In some situations, a client or server can add more than one audio attachment to a particular message. For example, a voice reply to a voice message can include the original voice content for reference. In such situations, the server SHOULD add an attachment for each voice segment and define the order using the PidTagVoiceMessageAttachmentOrder property (section 184.108.40.206).