D-Link DVG-7022S User Manual page 64

Select TCP/IP, and then click Properties.
Select "Use the following IP Address " and enter IP address, Subnet Mask, and Default Gateway.
Please note that an IP address in the same domain cannot be reused. Then, enter the DNS server
IP address (varies in different networks. consult your ISP's service for information). Click the "OK"
button and after completing the settings, users can use both the VoIP and network services
concurrently.