http://www.provu.co.uk/support_snom_ldap.html

How it works

Every time a user starts to dial a number or name on the Snom phone, an LDAP lookup is sent to the openLDAP server asking for "cn", "telephoneNumber" and "displayName". Any entry in your LDAP tree which has a telephoneNumber is displayed by the Snom phone. If the user is typing in a number then the results where the "telephoneNumber" begins with the digits dialled so far are shown in a list. If the user is typing in a name then the results where the "displayName" (or "cn" if "displayName" doesn't exist) matches the characters dialled are shown in a list. The search is not case-sensitive.
Use the up and down arrows of the silver navigation button on the phone to scroll through results.

Phone Configuration

• Server Address: enter the name or IP address of the server with OpenLDAP running on it.
• Port: 389 is the standard LDAP port and OpenLDAP uses this by default. Make sure there are no firewalls blocking this port.
• Base: this is the suffix setting configured in the slapd.conf file on the OpenLDAP server. E.G. "dc=provu,dc=co,dc=uk".
• Username: this is the bind DN. For example, if there is an inetOrgPerson entry with "cn=Paul Hayes" inside an organisationalUnit called "Staff", this setting could be - "cn=Paul Hayes,ou=Staff,dc=provu,dc=co,dc=uk".
• Password: this is the userPassword attribute for the DN specified in the above setting.
• Max Hits: maximum number of results to request.

CSV to LDIF conversion 

http://wiki.kolab.org/index.php/Csvtoldap.pl