I have an extention(x231) with a voicemail box, but I do not know the mailbox number (programming by others). When I try to assign mailbox number(mb231) that matches the extention(x231), the Flash unit says that extention already assigned. I went thru Mailbox 221 to Mailbox 252, none had extention 231 assigned. My only guess is connect a printer to the Flash and print a mailbox report. Is that a serial port or a parallel port?