Windows terminal server and Outlook

I am assessing an organization that has a central office with a LAN, plus several remote sites. The central office LAN runs Netware, and uses Outlook for its e-mail.

The remote sites dial in to a Windows terminal server in order to access an application that they use.

One of the complaints of the central office people is that the only Outlook users who show up in an Outlook directory list are the people in the central office. The people in the remote offices, who dial in, are missing. To sent e-mail to the remote users, the central office staff must use a private email address (such as hotmail) for the remote users. Is there any way that these remote users can show up in the central office Outlook directory list? Thanks.