Dear masviss. I agree with YOU at 100 percent and thanks all of You for your help in this forum. Our OS4K is serviced, I can consulation whith them too. I am staff engineer of telephony systems in state enterprise in Ukraine which is in WAR. Before 24.02.2022 I has planned to lean cources in unify academy but now its dont possible. I can learn OSK4 in practise but I dont have full manual (administrator manual or service manual) with descriptions of all funcshion, commands, etc.