Google announced official Google Voice iPhone app with a post on official blog Google has said that Apple has approved Google Voice, and app is finally available on the App Store and can be downloaded free of cost. For now, Google Voice is available only on the American app store.
Google Voice allows you to make VoIP calls at very low cost to mobile and fixed calls to a Voice ID instead are always free. Also sending SMS is free, at least in the United States, it is unclear whether it will be so in other countries. The software also supports push notifications for missed call or message.
You can download Google Voice for iPhone (Download Link). You’ll need an iPhone with iOS 3.1 or later and a valid Google Voice account to use the app. At this time, Google Voice is available in the U.S. only.