The solution for this is as follows:
1. Go to Management Console > Settings > Parameters and search for CSTA_USER_AGENTS Parameter .
2. Replace the value of this parameter with the value below:
Fanvil X,Fanvil C400,Fanvil C600,Fanvil H,Htek UC8,Htek UC9,snom3,snomD,snom7,snom8,Yealink...