The OBi200 allows you to make and receive phone calls using your high-speed internet, your regular home phone and a "VoIP" Internet phone service provider like Google Voice. This enables you to call free or at a fraction of the cost a traditional telco would charge. Refer to the product page and forum thread for additional details and discussion.
Our research indicates that at the time of this post, the Polycom OBi200 (Formerly OBIHAI OBi200) VoIP Telephone Adapter with Google Voice & SIP is $10 lower (20% savings) than the next best available price from a reputable merchant with prices starting from $49.99. -Corwin