Shared voicemail box

I have a group of users that I want them to share one mailbox, the mailbox will have the same greeting message, a professionally recorded wav file, that I have, and also should be able to listen to the messages from any of their extansions.
I’m using Asterisk 1.4.2 and odbc storage for voice messages

2 questions:
1- where to plave the wav file
2- how to make them all check the messages