We all know about the popular Google Voice Service. It's a VoIP based service through which any person with a Google Voice account can call any regular phone number from a PC or mobile phone connected to the Internet.
For a user residing in USA or Canada, the calls from Google Voice account are absolutely free within the country limits. For users outside North America the calls are charged according to rates specified by Google. The rates are the cheapest among any other VoIP service or Telecom service providers worldwide. Unfortunately this hugely popular service is not yet available to Google users in India.