Google Inc. (NASDAQ:GOOG) has been having some success with Google Voice. The service has about 1.42 million users and 570,000 of them use it every single day. The numbers were revealed in an FCC document filed by Google and discovered by BusinessWeek.

The same document revealed Google’s plans to expand the Voice service abroad. Google Voice allows users to have a universal number that forwards to a person’s mobile phone, work phone, or home phone. Google Voice was developed through the acquisition of GrandCentral. Google supposedly payed close to $50 million for GrandCentral in July 2007.

Google is making use of the GrandCentral VoIP service that they acquired back in July 2007.  GrandCental has been rolled into a service called Google Voice. Google Voice includes all of the features that GrandCentral had when the property was acquired plus several additions.

Google Voice allows users to sync phone numbers and transfer calls to all of their devices.  Voice calls can be converted into text messages and there is the ability to call multiple parties.  Another feature that Google voice has that gives Skype some competition is discounted international calls.

Through Level 3, Google has already reserved 1 million phone numbers. “If you are a GrandCentral user, over the next few days you will be prompted to upgrade to Google Voice.  Currently only GrandCentral users have access to Google Voice, but we will be opening up the new service to new users soon,” stated the GrandCentral website.

[via ReadWriteWeb]

GrandCentral^[1] is a service that has the ability to connect one phone number to all the devices that one owns. For example, a home, work, and cell phone can all ring at once and can be used interchangeably in mid-conversation.

Rules can also be set so that family members or friends get redirected to certain devices. There is also a feature called ListenIn that allows users to listen to their voicemail in real-time while callers are leaving messages. Voicemails can be made from MP3s and conversations can be recorded at any time.

And now Google owns the company. Google bought the company because they believe GrandCentral “enhances the collaborative exchange of information between our users^[2].” Google is moving the technology onto their own networks and GrandCentral’s team will start working at Google. The service is still in Beta mode and to gain access, invitations are needed.

TechCrunch broke the acquistion rumor about a week ago^[3]. The suspected amount spent on GrandCentral is roughly $50 million.

[1] GrandCentral.com
[2] Official Google Blog: All aboard
[3] TechCrunch: Deal is Confirmed: Google Acquired GrandCentral