It is a great product, I ordered OBi110 from Amazon.
The most great part is:
OBi110 can work with Google Voice.
The product is provided by Obihai.
To Setup it work with Google Voice, go to OBiTALK.
After setup, I can use this phone to call US or Canada phone for free.
Here is the guide for configuration and setup.
http://www.obihai.com/googlevoice.html