Dial *321[EXT]
Where [EXT] is, you need to put the extension number of the voicemail, in the following example it would be 102
Dial *321102
Dial the Password which is the voicemail PIN
Dial 0 for advanced mailbox options
Dial 1 to record the unavailable message
Once you have finished recording the voicemail message, press #
To accept the voicemail recording, press 1
To listen to the voicemail recording, press 2
To rerecord the voicemail message, press 3