I've been using Google's
What does it do?
Simply put, Google Voice helps you manage your phone numbers. Sign up for the service and pick an area code. The phone number you get will then act as a central connection, forwarding the calls it receives to your home phone, cell phone, work number, and any other phone you might have.
It's easy to set up rules for what calls go where, and the service comes with handy extras like call recording and emailed voice mail transcripts. The last time I changed my landline provider, signing up for GrandCentral was an obvious choice.
Competition and competitive advantage
Now, the service isn't totally unique. My old Vonage
And if you ever change service providers, it only takes a couple of clicks to keep your Google Voice forwarding current. It's a hassle-free lifetime number -- assuming that Google stays in business forever.
Big G in the house
It's also a great example of how Google can leverage its experience from several semi-random experiments and cook up something better than the sum of the parts. The Google 411 service that made so little sense on its own has trained the voice recognition algorithms that fuel Google Voice's text transcripts. And once your call has been transcribed, you can find it with text-based searches, just like you would for Gmail messages. Sweet!
Nothing's stopping the phone companies or even Microsoft