Obihai had officially announced Obi devices are supported by Google Voice. With a Google Voice account and a companion OBi device you can make and receive VoIP calls on a regular home phone. Obihai adapters have been around since 2011, with the latest update and the Google Voice official integration, the installation process is easier than before.
All you need is a Obi device (Obi100, Obi110, Obi200, Obi202), a good internet connection, a regular phone. Although you need to pay for the OBI device, after you pair it up with Google voice, you will save a lot from your phone bill every month.
First thing to do is get a Obi device, review the comparison of OBi Devices (Obi100, Obi110, Obi200, Obi202) first and choose a suitable Obi device.
OBI mostly are sold on Amazon.com. Below are links to Obi100, Obi110, Obi200, Obi202 Amazon pages.
*You might want to port your home phone number to Google Voice first if you want to keep the number for $20 one time charge. However, you will not able to port your home line number directly to Google Voice because Google's restriction. You can port the number to Tmobile or AT&T's prepaid service (cost about $10), wait for couple days after the porting process completed , then submit the port request to Google Voice.
After you received your OBI device, for example OBi202, following the procedures below to set up your OBI box.
1. Open the box and plug in the cables. AC adapter, telephone line, and ethernet cable to router.
Here is how the connection should looks like:
2. Go to your computer and visit ObiTalk.com. Register a account and following the directions.
3. Dial a test phone number from the phone connected to the OBI device when it asks.
The new setup page now have option "Sign in with Google Account" button makes the set up even easier. Accept the permission request when it asks.
4. Test your phone. Call your OBI connected home phone number to see if the phone rings. Almost done.
5. Log in to your Google voice account, make sure the option "Forwards to Google Chat" is checked.
Without this you will not able to make any call from your phone.
If you don't see the option in your Google Voice account, follow this guide to active the option: Quick trick for Missing Forwards calls to Google Chat Option in Google Voice Account