Google Voice is Coming as an upgrade to GrandCentral
As reported in the Official Google Blog, Google is preparing to replace its GrandCentral voice service with Google Voice. Google Voice is designed to provide you with a universal number that will ring your office, home, and mobile numbers while providing a single voice mailbox and a rich set of features.
For now, only existing GrandCentral users in the US can upgrade, but Google is promising to extend availability in the near future.