I signed up for Google Voice forever ago when it was still known as "Grand Central", before Google bought it. I had a phone number for it but I never really utilized it until Google turned it into Google Voice and created more options for voice-mail management.
At the time, I was with Sprint and they had just implemented conditional forwarding where they did not charge an additional fee to forward calls. Conditional forwarding is the ability to forward calls to a different number based on certain conditions. In the case of Google Voice, you set up a conditional forward to your Google Voice number based on a call going to voicemail.
Once you forward to Google, you can do several things - you can just answer the call with it's voice-mail service and you can also tell it to forward to another phone number for a certain number of rings before rolling back to voice-mail.
Google's voice-mail is nice - it transcribes if it's able, it's accessible via phone as traditional voice-mail is, you can have it send you text messages of the transcripts, and there's various smartphone apps for iPhone, etc and native support in Android. There's also a mobile web interface if all else fails.
Checking voicemail is a task that I abhor, so being able to see transcripts of messages is a great thing. They are generally accurate enough to get the gist of it - I'd say I have to listen to about 10-20% of the messages I get anyway.
Recently, Google opened up voice to all of its account holders. I have multiple Google accounts for various things, so I recently added some numbers.
My main number is still mostly unused - I have given it out to some things, but it forwards to my cell phone number. Since number portability is so common, I expect to have the same cell phone number forever and so the ability to have another number that you own and can forward anywhere isn't of much use to me at the moment.
What is useful is a second phone number that I can give out to individuals and organizations for which I believe it might be used in an attempt to solicit without my consent. This phone number goes nowhere but a voice-mail box for which I recorded a greeting - and an email is sent to my main gmail account. Like most people, I don't want to receive cold calls on my phone, particularly my cell phone. I recently subscribed to the Star Tribune and gave them this number - they can leave voice-mails to their hearts content about being a subscriber on my dead end voice-mail box, and I can still get any relevant messages from them. I plan to employ this number for most everything I have to give out to organizations from now on, and is a convenient number to use for the alumni associations of my Alma Maters too.
I'm very happy with the Google Voice service so far. Like most things Google does, they do it well and they constantly iterate.
