Registering a frequently used fax numbers on this machine will save you the trouble of entering them each time you send a fax.
For details on how to register, refer to Here.
When an LDAP server or Active Directory is used for user management purposes, you can search for or specify fax numbers using the server. To use the LDAP server to specify a destination, you must register the server on this machine.
The registration procedure is explained using Web Connection. For details, refer to Here.
For details on how to search using the LDAP server, refer to Here.