I follow the instructions and go to settings and when I look to forward it to google chat, it's not even there. The other phone number is there, but not google chat. How come?
You must log in to gmail and make a call with Google chat. Use the same login you use for Google Voice. You may need to install the Gchat plugin when you do it. After that it should appear in Google Voice.
I made a call using google voice, but still nothing. Is it necessary to make it through gmail? is it not the same thing?
It is necessary to make it through the gmail chat. google voice and google chat are not the same thing. the google voice is just a forwarding service for phone numbers. obihai is configured through the google chat to actually send/receive calls.