Use an existing Google Voice number
If you already have a Google Voice number you want to continue using as your Fiber Phone number, it's a simple process.
Sign in to Fiber using the email and password you use for your Fiber account. Your Account page appears.
Under Plan Details, click Manage Plan.
In the Overview section, under Subscribe to Additional Services, click Add to Plan next to Phone.
Follow the on-screen instructions and select Use your current Google Voice number; then complete the Fiber Phone setup flow. Once completed, Fiber Phone will use your Google Voice number.
If you like, navigate to the Phone tab in Fiber to explore the Fiber Phone settings. You can start using your Fiber Phone number on your devices through Google Hangouts right away.