How To Get A Google Voice Phone Number

1. Go to your Google Account settings

2. Under the heading "Email addresses and usernames", and next to your email address, click the "Edit" link

3. Set the Country to "United States" and click "Save"

4. Select "Language" and choose "English (United States)"

5. Go to the web page "google.com/voice":

6. Open Voice Settings

7. Click on "Get a Voice number"

8. Click "I want a new number"

9. Search for a number that you like

10. Choose a PIN and accept the terms

11. Enter a US number to associate with the account (this is mandatory to activate the Google Voice number, but can be removed once it is active, so you can use a friend's number if you don't have your own number in the USA).

12. Click "Call me now", answer the call and when prompted, enter the code

Once you've entered the code your new Google Voice number should be active.

It is also recommended to install the voice and video component for your web browser, so you can make and receive calls directly from within Gmail.  For Chrome, this component is called "Google Talk Plugin", and can be installed from within Gmail, using the Google Talk widgets.