This has been confirmed to work on a Yealink T46S.

On the phone's web interface, navigate to “Directory” → “LDAP” and fill out as follows – example for “EPVPN”:

Copy-paste-able text from the screenshot:

Enabled

(&(|(sn=%)(l=%))(telephoneNumber=*))
(&(sn=*)(telephoneNumber=%))
LDAP
guru3.eventphone.de
389
dc=EPVPN,dc=eventphone,dc=de
ou=EPVPN
$random
50
sn
cn
%sn
Version 3
Enabled
Enabled
Enabled

(Thanks to this message in the "DECT für Enthusiast:innen" Matrix room).

• LDAP Phonebook