Hold down the "1" key until the speed dial calls your mailbox. It's the default speed dial on every new blackberry. Or in the phone application click menu and then "call voicemail".
Location: The Land of Ferraris, Moviestars, and Bumbs
Model: 9000
PIN: & Teller
Carrier: AT&T
Posts: 590
your voicemail has an access number attached to it for different carriers. You can't access voicemail without that number programmed into the phone for voicemail retrieval. Its not a Blackberry issue, its a service provider issue. Call your service provider and have them assist you with the setup, they will.
or you can just call your own number and press either # or * (can never remember which is which) and put in your password (if you havent set one up, some carriers have it defaulted to the last four of the phone number)
On my Pearl, you can't change your greeting unless you empty your voicemail box of both new and saved messages. So the procedure is 1) call your voicemail; 2) empty your mailbox of new and saved messages; 3) listen for the prompt and follow it for a couple of links until you get to the one that lets you change your greeting. (They really should have made this feature easier to use!!)