Outlook and exchange do not support calendars using POP3. OWA would be a better solution for remote connectivity.
Can you give more details of exactly what you mean please? Are you trying to open calendars which belong to someone else’s mailbox or your own? What method are you using to open them “remotely” as you put it? Are these Exchange mailboxes? Exchange 2003 does not allow opening someone else’s calendar in OWA, but Exchange 2007 does. What version of Exchange? If not Exchange, what mail system please? We can only guess and take a stab in the dark without the details. Thanks!