With so much news lately about Google Voice, those who haven't kept up on every tiny development have found themselves lost. What exactly is Google Voice? Is it a phone redirecting service? VoIP? Voicemail? All of the above? None of the above? Even some of our staff members are confused about what Google Voice offers and why people would want to use it, so we thought it would be helpful to offer a guide to Google Voice for those just tuning in.

Google Voice originated as GrandCentral, an independent company that hit the scene in 2005. GrandCentral allowed users to register a new phone number and direct it to ring multiple phones; it could also collect messages and act as your personal switchboard operator. This sounds boring on the surface, but it provided a number of cool features, such as the ability to listen in on voicemail messages as they were being left or to tell a specific number that your phone number is no longer connected (great for stalkers and crazed PR people, who are kind of like stalkers). Google acquired GrandCentral in 2007, and promptly sat on the project for nearly two years before it relaunched the service as Google Voice in March of 2009.

Google didn't just take GrandCentral and slap a colorful logo on it, though. The search giant made a number of improvements on the already nifty service, and it has become a must-have for the handful of early adopters who were lucky enough to get in either as a grandfathered GrandCentral user or through an invite. Let's look at what you can get out of the (currently) free service.

Calls

Users can register phone numbers in practically any area code they want, choosing local or faraway destinations. Under Google, the service now allows you to choose words or witty phrases that your phone number spells out (not present under GrandCentral), so have fun and good luck trying to grab (312) 55-BALLS. You cannot port an existing number of yours to Google Voice, however, which may be viewed as a downside to those who are married to a longtime cell number or the like. (Update: Some readers have written in to say that it is possible to port a number.)

After that, the most basic service that Google Voice offers is call forwarding. Forward calls to as many or as few numbers as you like, and you can even forward them to different phones based on who's calling. This is helpful if you're like me and don't want check-ins from the boss going to your cell phone, but you do want calls from dear ol' mom and dad. You can also set certain groups (or individuals) to be sent directly to Voicemail, to the Spam folder, or block the call altogether.

Another useful feature is the ability to screen callers—you can either have the calls sent directly to your phone with no filtering, or you can have Google ask them to say their name first. The service will ring you, tell you who's calling, and give you the option to take the call or send them to voicemail. This is nice for numbers that you don't recognize, as you wouldn't know who they're from otherwise. You can also change this behavior depending on a group (Friends, Family, Work, etc.) or an individual basis. So it's possible to always screen unknown numbers, for example, and always forward your friends directly. This is where the service gives you the ability to listen in on voicemails as they are being left, too.

Receiving calls is just the beginning. Through Google Voice, you can also make free calls to any US number. These will appear to originate from your Google number even when you're calling from your cell or your home line—the receiver's caller ID will show your Google number (therefore not giving away your other numbers).

You can also record phone calls that you've received, although this functionality does not work with outgoing calls you make. But if someone dials in, it's possible to record interviews, catch important details for transcription later, or come up with some other nefarious plan for your Google Voice recordings. It's very helpful, although it would be more helpful if these recordings were transcribed like voicemails are (read on).

Voicemail

By far the coolest feature of Google Voice's voicemail is that the service automatically transcribes the voice messages left by callers and then sends the transcription to you through a variety of mediums. For example, I receive my voicemails via text message and e-mail when they come in. Not only is this faster than listening to the message a few times to get all the details, but it also gives me a written record that is easily stored for future reference. Keep in mind, however, that the transcription is not always 100 percent accurate—from experience, I find that it's about 80 percent, though you can usually fill in the blanks by looking at the context.

In any case, you can always listen to the voice recordings online. Additionally, you can download an audio file of the recordings for your records, or grab some embed code for putting embarrassing postings on the Internet (nota bene: people will usually be unhappy if you do this without their permission). Or, if your voicemail is better suited for someone else—another family member, a coworker, etc.—you can forward the message onto that person.

SMS and miscellaneous features

When people SMS your Google Voice number, the message will go directly to one or more (however many you have set up) mobile phones. You can respond to those SMSs directly from the phone, and that response will appear to come from your Google Voice number. The cool part, though, is that you can also send and receive SMSs right from the Google Voice Web interface, meaning that you don't have to whip out your phone every time you want to text your friend to ask why he's late picking you up—assuming you're in front of a computer already, that is. Google Voice lets you archive your SMS logs too so that you can reach them anytime from the website.

For those worried about wasting mobile phone minutes, Google Voice lets you transfer your calls to another phone, right in the middle of the call. When you're on a phone call and press the * button, your other phones listed on the account will ring. When you pick up the phone you want to use (say, your home landline), you can hang up on the original phone and your call will still be in progress.

There are a handful of other features that Google Voice offers, but those are most of the big ones. Those of us at Ars who have been using Google Voice since the GrandCentral days are really pleased with the changes Google has made thus far, and we have begun using it for everyday things like our work-related calls and routing calls between phones.

Whether all of these services will remain free forever is still up for debate. But, given Google's usual patterns, it's unlikely that the company will begin charging regular users for the service. Based on their other services, Google probably has some plan up its sleeve to offer a version of Google Voice for businesses that it will charge for (similar to its already-existing Google Apps package). If you can get access to Google Voice, give it a try, if only for the call filtering and voicemail transcribing features.