Google is preparing to launch Google Voice, which is based on the GrandCentral telephone service that it acquired in July 2007. It'll offer a single number that can ring home, work and mobile phones, discounted international calls, an online voicemail inbox and the ability to screen calls by listening in 'live'. In addition, Google Voice can provide transcripts of voicemail and will archive SMS text messages sent or received via the service. Google Voice is currently only available to US-based GrandCentral users, although Google says it'll be offered to other people soon. [Google blog]