Yesterday, Google announced on the Google Voice blog that they are opening up the service to everyone.
Previously, in order to use Google Voice, you would have to get an invitation, either from Google or from someone who already had an account.
Google Voice is a free service that provides users with a phone number that can be used to ring multiple phones when you receive a phone call.
If someone calls you using your Google Voice number and you don’t answer their call, they can leave you a voicemail, which you can access online. The voicemail also gets transcribed so that you can read it using the Google Voice web interface.
Also, Google Voice allows you to send and receive text messages, either from your phone, using a Google Voice application, or by using the Google Voice web interface.
Another feature of Google Voice is that you can initiate phone calls from the web interface, which will call your phone and then call the person you wanted to talk to, as well as view your call logs online.
For a complete list of features, you should visit the Google Voice features page.