There is a detailed description at [[https://service.snom.com/display/wiki/LDAP+Directory]].

^ Setting                 ^ value                                                       ^
^ LDAP name filter        | %%(&(|(sn=%)(l=%))(telephoneNumber=*))%%                    |
^ LDAP number filter      | %%(&(sn=*)(telephoneNumber=%))%%                            |
^ Server Address          | guru3.eventphone.de                                         |
^ Port                    | 389                                                         |
^ Base                    | ''dc=eventphone,dc=de'' / ''dc=EPVPN,dc=eventphone,dc=de''  |
^ LDAP name attributes    | sn l ou                                                     |
^ LDAP number attributes  | cn telephoneNumber                                          |
^ LDAP display name       | ''%sn (%l)'' / ''%sn (%ou)''                                |
^ LDAP over TLS           | optional - use Port 636 if ''on''                           |
^ Predict Text            | ''on'' if you want to use T9                                |