A voice mail message takes some time before it begins to play.
Perform this procedure to resolve the delay in the appearance of voice mail messages:
Refer to Cisco Unity Messages for more details.
Voicemail behavior problems
Delayed response: tone, call stage, music, greeting, prompt, message, announcement, etc.
While listening to voicemail messages
When checking mailbox
Unity version earlier than 3.1(2)
Unity version 3.1(2) or later