Delete Voice Mail on Phone that has never had a pin assigned?

I have a Polycom 311 desk phone that was originally assigned to an employee who left before setting up the phone. I plugged in the phone in our spare office, but there are voice mails on it. There was never a pin assigned and I cannot find a way to "reset" or delete the voice mails without this pin. Is there a generic pin that I can use until phone has a "real" owner?