If using a fixed IP address on your phones you can enable a setting on the phone called DHCP which will enable a router configured for a dynamic IP address to provide a connection to your phones - please follow the instructions below:
Step 1: Using the SPA, press the Setup button.
Step 2: Go to Network (9) using the Navigation button.
Step 3: When the Network section appears, go to DHCP Enable (1). Select Edit soft key. Set it to Yes by pressing y/n soft key. Press Ok soft key.
You may need to re-boot your phone after doing this so that the phone then receives an internet connection from your router.