Nope, but I can tell you right here, it's easy.
1. First you obviously need to sign-up for Grand Central and Gizmo5.
2. After signing up for Gizmo5, you'll get a free SIP number. It looks like 1-747-330-1234
3. Log in to Grand Central and add your SIP number to the account. When you go to add the number, use the pull down and select "Gizmo". It lets GC know you use the Gizmo5 software.
That's it... when you go to make a call in GC you'll select your Gizmo5 number and it will ring in on your Gizmo5 software. Answer it and you'll hear, "This call is being connected by Level3 communications". It'll ring and the person you called will pick up...
When someone calls you, it'll ring on your Gizmo5 software and you'll hit "answer" and then go to the dialpad and hit "1" to allow the incoming call.
My call quality is better than my old AT&T landline.