Insight Communications offers phone service over their cable broadband modems. Many of the phone features are exactly like other phone service such as call forwarding. To enable call forwarding on a Insight Communications digital phone follow the directions below.
Recently Gizmo5 added the ability to configure your Google Voice account within the Gizmo5 interface which allows for you to configure any SIP device (soft or hardware) to have free voice. I happened to have a SPA-2000 around so the below describes how to configure a Sipura SPA-2000 using Gizmo5 and a Google Voice account for free voice. For this howto you will need a SPA-2000, a Gizmo5.com account, and a Google Voice account.