The system supports H.323 IP telephones by default. If these are not required for the customer installation, we recommend that the system's SIP telephone support is disabled.
To disable SIP telephone support:
•! WARNING
The processes below require the IP Office system to reboot in order to apply any changes made. The reboot ends all current calls and services.
1.Start IP Office Manager and receive the configuration from the IP Office system.
2.Select System.
3.Select LAN1 and select the VoIP tab.
4.Check that SIP Registrar Enable is not selected.
5.Repeat the process for LAN2.
6.Click on the 
save icon and save the updated configuration back to the system.