Google Voice is a telecommunications service by Google. Launched on March 11, 2009. Google Voice had some 1.4 million users in October 2009, 570,000 of whom used the service 7 days a week.
Google Voice is an Internet based service that allows you to give everyone one phone number and forward it to multiple phones. That means that as you switch jobs, change phone services, move, or even go on vacation, your phone number stays the same for people trying to reach you.
Google Voice also allows you to screen phone calls, block phone numbers, and apply rules based on the caller. When you receive voicemail messages, Google transcribes the message and can send you an email or text message to let you know about the call.
Google Voice is only available in the US, and you still need a phone to use it.
Google Voice accounts are free. The only feature Google charges for is making international calls. However, your phone company may charge you for minutes you use answering calls or data access for using the website, depending on your plan.
Getting an Account:
Google Voice has a limited number of slots, since each user needs a separate phone number. In order to get an invitation, you need to sign up on the waiting list.
GrandCentral, the service Google purchased to create Google Voice, had a friend-referral invitation system. Each user was given invitations they could pass on to their friends, similar to the old Gmail system. Google Voice does not work this way. Knowing someone who has an account won't help you get one. You must wait on the waiting list, although the Google Voice team has occasionally given out invites on Twitter.
Finding a Number:
Google Voice lets you select your own phone numbers from their available pool. Be aware that you may not be able to change this number again, so make it a good one. (Former GrandCentral users were allowed to spend $10 to change their number, but there's no guarantee that will remain.)
In order to make this process easy and meaningful, Google lets you search the numbers by area code and by text or number sequence. Spell out your name, find a meaningful phrase or easy to remember number sequence, like "PWN-AGES" or "1234."
Once you have a number, you'll need to set up and verify the numbers you want it to ring. Google won't let you put phone numbers in that you don't have access to answer, it won't let you forward to the same number on multiple Google Voice accounts, and it won't let you use Google Voice without at least one verified phone number on record.
Google does not forward calls to phones that need extensions, pauses, or special characters. This is a frequently requested feature, but they don't support it at this time. You need a direct line to have your number forwarded.
Google provides apps for both Android and Blackberry phones. These allow you to use Google Voice for visual voice mail, and they also allow you to use Google Voice as your outgoing phone number on your mobile phone. That means everyone sees your Google Voice number in their caller ID instead of your cell phone's number.
You can forward your calls to multiple numbers at the same time. This is very handy if you've got both a home and mobile number you want to ring. You can also set numbers to only ring during certain times of day. For instance, you may want your work number to ring during weekdays but your home number to ring on weekends.
You can make calls through your Google Voice account by accessing it on the website. It will dial both your phone and the number you're trying to reach and connect you. You can also use the Google Voice phone app to dial directly.
When you receive a call forwarded from Google Voice, you can choose to either answer the call or send it directly to voicemail. With the call screening option, new callers will be asked to state their name, and then you can decide how to handle the call. You can also set certain numbers to go directly to voicemail if you choose.
You can set your own voicemail greeting. Voicemail messages are transcribed by default. When you receive a voicemail message, you can play it back, view the transcription, or do both "karaoke style." You either need to view the message on the Internet or using a Google Voice phone app.
You can only forward Google Voice calls to US numbers. However, you can use Google Voice to dial international calls. In order to do this, you need to purchase credits through Google Checkout. Then you can either use the Google Voice mobile app or Google Voice website to make your call.
If you want to include phone contact information on a website without actually including the number, you can copy and paste a Google Voice phone widget. This will ring both you and the caller's phones without revealing your phone number to the caller.
What it isn't
Google Voice is not, however, the be-all and end-all of telephone services.
It isn't a Voice over IP (VoIP) service like Skype or Vonage. You still need a standard phone connection (cellular or landline) to and from Google Voice.
Nor is it fully integrated (yet) with the iPhone. As I write this, Apple does not allow Google Voice iPhone apps. There is however, a very good iPhone-optimized version of the Google Voice web application. Google's native Voice applications for Android and Blackberry phones are very capable, and the federal government has expressed concern, so there is hope that Apple will approve a Google Voice iPhone app.
The bottom line
In many ways, Google Voice turns your "dumb" phones into smart phones. You can understand why cell phone vendors and carriers might not be too thrilled about it: the service allows Google to insinuate itself between you and your carrier, and provides free replacements for many of their premium services.