To access the configuration page of the Linksys SPA3102, you simply need to do the following.

Open your web browser (internet explorer, mozilla firefox, etc), and in the address bar type in http://192.168.0.1 OR http://192.168.1.1

If this doesn't work, plug a phone into the device and dial ****110#, this will give you the IP address of the device.

You are now in the configuration page.