3CX includes a company phonebook where you can save contacts for company-wide access. This company phonebook is synced with the phonebooks of IP Phones as well as the 3CX apps.
Tested with: 3CX, local PBX Version 20.0 Update 6 (Build 724 Release) - Gigaset P710 / P810(B) / P82x / P85x(B)W
The phonebook is without user interaction automatically updated once a day and when provisioning is started.
You can open the 3CX phonebook via: