Previously, Google used to send us email notifications of voice messages and we have to log on to Google Voice to play the messages, now Gmail allows us to play within the email itself via the Labs feature.

"Previously, clicking 'Play message' opened a new page in your browser, but starting today, you can play voicemails right in Gmail. Just turn on the Google Voice player from the Gmail Labs tab under Settings and whenever you get a voicemail notification, the player will appear right below the message itself." - Official Gmail Blog: New in Labs: Play Google Voice messages in Gmail

To enable this feature go to Gmail Settings --> Click "Labs" --> Enable "Play Google Voice Player in mail" --> Click "Save Changes".

When we listen to the messages in Gmail, it will update the "read" status of that call in your Google Voice account.

Google Voice also allows us to manage our communications with a single phone number and connect our home, office, mobile, and landline phone numbers to one Google Voice number and be connected wherever we go. It also blocks spam calls and can record different greeting messages for different groups of callers.

If you don't have a Google Voice account, you can apply for an invitation here.