Found this in the Google Voice Forum.

Part 1: how to setup GV with Gizmo

1. goto »https://www.gizmocall.com/gc/open.html
2. click register and create an account right away.. doesn’t even have to be a valid email address
3. u can login to the flash app right away without validating anything
4. u will see a the dial pad with $0.00 balance. click on the $0.00
5. it will open a new window with buy credits, ignore it and click on ‘My Account’ or ‘MY’ link on the top-right
6. u will see ur new gizmo5 sip number there, copy it, come back to googlevoice and add it in the GV phone settings
7. when u click connect/contact in the GV window, remember the 2 digit code and wait for the call on the gizmo5 flash app window.
8. accept the call, wait 1 sec and then press the 2 digit code on the dial pad.
9. go back to GV page to see ur number being validated and accepted in real time.
10. Next register for an account to obtain a free US phone number with either »www.sipgate.com or »www.ipkall.com to forward your GV account to.(This is now necessary because GV now requires a US based number.)

Part 2: how to signup with ur gv invite from outside usa.

1. download and install. »www.ultrareach.com/downloads/ult···/u95.zip
2. once installed.. use ie browser. check ur ip on the map »www.privacy-gateway.com/whatismyip.html it should be somewhere in usa. u r in.
3. use ur gv invite wisely.

if ur invite says invalid or doesn’t do what its supposed to, use ie browser and the steps below.
1. copy the inv. code link into ur clip board
2. log out of gmail
3. log back into the gmail account u want the number 2b tied to
4. open a new tab and paste the link in ur clipboard.

ref : http://www.dslreports.com

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