Grand Central is Google's free telephone management system.
I've been a Grand Central user since 2007, though we haven't really incorporated it into our life in a big way. Whenever we need to submit a phone number in a public way (we have it engraved onto the back of an iPod, for example), I always use our GC number. Grand Central is being replaced by something called Google Voice.
Right now, the Google Voice service is only available to Grand Central users, but Google is offering a notification sign-up list.
I wrote the following about Grand Central in November 2007:
GrandCentral is a free service which allows you to route calls made one central phone number (which you get from GrandCentral) to your selection of destination voicemail boxes an other phones. Here are some features:
* Screen Callers - GrandCentral looks up callers from its address book and shows you who's calling. If they're not in the book, it asks the caller for their name and stores it.
* Block Callers - Just add numbers to a blacklist.
* Listen In - Hear people leaving messages, and pick up if you wish.
* Call Record
* Notifications - receive email or SMS voicemail notifications
* Ring Different Phones - ring different phones based upon who is calling
* Greetings - different greetings based upon caller numbers
* RingShare - custom rings for callers by their ID
* WebCall - people call you from a web page without showing your number
* CallSwitch - while talking to someone on any of your phone locations (cell, home, work, other cell, etc.), press the star (*) key - all your other phones will ring and you pick one up, the call is transferred - very cool
* Click2Call - while using the Web interface for GrandCentral to view contacts, click "Call" - GC will call you, and call the contact for you
GrandCentral is in beta, and currently on "by invitation" from other users, but you can request an invitation on the site. GrandCentral was acquired by Google in June 2007. Here is Google's description of the service:
GrandCentral offers many features that complement the phone services you already use. If you have multiple phone numbers (e.g., home, work, cell), you get one phone number that you can set to ring all, some, or none of your phones, based on who's calling. This way, your phone number is tied to you, and not your location or job. The service also gives you one central voice mailbox. You can listen to your voicemails online or from any phone, forward them to anybody, add the caller to your address book, block a caller as spam, and a lot more. You can even listen in on voicemail messages from your phone while they are being recorded, or switch a call from your cell phone to your desk phone and back again. All in all, you'll have a lot more control over your phones.
GrandCentral will no doubt be monetized at some point. Perhaps it will become a pay service, or perhaps Google will find a way to insert ads in the onilne content or (hopefully not) in the phone messaging system. Perhaps it provides a solution for you.