After 16 months of dealing with Apple, Google has released the Google Voice application for the App Store. Google submitted this application a year and a half ago, but decided not to accept it. Apple also rejected third-party apps that have Google Voice functionality too.
Eventually the government had to get involved where both parties had to disclose their relationship with each other and with carriers. Apple said that they did not like the Google Voice application because it was too similar to the functionality on the iPhone.
The Google Voice application is free and it lets you make calls right from the app. When you dial a number, it automatically appears on the iPhone Phone application and makes the call from your Google Voice number.
When you receive a call to your Google Voice number, it will come in to your regular Phone app. YOu can also send and receive text messages from the application. And you can also listen to your Google Voice phone numbers through the app. The Google Voice application lets you access the phone contact list and it makes it easy to call them using Quick Dial Contacts.
[Google Voice Blog]