Google Voice doesn't buy me anything since I don't have Gizmo acct. to support it. I couldn't get my Vonage main acct. to work via SIP either, and the Vonage softphone acct. only gets me 500 minutes via SIP client, so I went ahead and did a $3/mo. Skype acct., to go w/ 500 minute T-Mo plan when I got the 900. It's nice that I can send my cell's # as caller ID thru Skype, and has been working pretty well for me.