Google released Google Voice to public(well so far for people in US only) free of charge today. If you have not heard about Google Voice and want to know what it is, then watch this video below:
Once you sign up and choose a Google Voice phone number, you can add your home, work, or mobile phone to your Google Voice account, then once someone call your Google Voice phone number, all phones that you add will ring, pretty cool. Also, you can set up your voicemail in Google Voice and have your voicemail transcript sent to your email account. All your phone call history, including voicemail, text message, etc, are stored in Google Voice account.