If Sametime server setup uses an LDAP user directory rather than native Domino, then set $LPSametimeLDAP to true, thereby instructing Discovery Server to perform an LDAP lookup on a name to get the common name, which it then submits to Sametime for status updates.
Note To ensure that K-station People Awareness features work properly when third-party LDAP directories are People sources, you'll need to configure your Sametime server to work with third-party LDAP servers. Refer to the Domino 5 Administration Help topic, Referring LDAP Clients to an LDAP Directory.