| Google Voice works by sending an API call to Google, asking Google to dial your phone. After you answer the phone, Google then dials out to the number specified in the API request. For instance, if I wanted to call my parents, the app on my iPhone would send a HTTP request to Google with their number. Google then dials me, and once I pick up, it would dial my parents. My parents would see the Caller-ID from Google, not from my Phone. If they call back this Caller-ID, Google would answer the call, and then dial my phone, so I could speak with them. If I didn't answer, then Google would record a voicemail message. This message would be both emailed to me, and accessible via API from the application that I originally dialed them with. Google's ultimate plan is to allow you to "port" your number to their service, so that your normal, regular number becomes the one on their caller-id, and AT&T assigns you a new number that you would never give out. |