You could also specify which phones would ring when certain people called. (For the really annoying people in your life, you could even tell GrandCentral to answer with the classic, three-tone “The number you have dialed is no longer in service” message.)

Also very cool: Any time during a call, you could press the * key to make all of your phones ring again, so that you could pick up on a different phone in midcall. If you were heading out the door, you could switch a landline call to your cellphone.

GrandCentral also offered telemarketing spam filters, off-hour call blocking (“never ring my BlackBerry on weekends”), and a dizzying number of other functions. For people with complicated lives, GrandCentral was a breath of fresh air. It felt like a secret power that nobody else had.

Then, in 2007, Google bought GrandCentral. It stopped accepting new members, ceased any visible work on it, and, apparently, forgot about it completely. The early adopters, several hundred thousand of them, were able to keep using GrandCentral’s features. But as time went on, their hearts sank. In January, Salon.com summed it up in an editorial called, “Will the Last One to Leave GrandCentral Please Turn Out the Lights?”

As it turns out, the joke was on them. Google was quietly working on GrandCentral all along. Starting Thursday, existing GrandCentral members can upgrade to Google Voice. In a few weeks, after debugging the system, Google will open the service to all.

Google Voice starts with a clean, redesigned Web site that looks like an in-box, à la Gmail. It maintains all of those original GrandCentral features  but more important, introduces four game-changing new ones.

FREE VOICE MAIL TRANSCRIPTIONS From now on, you don’t have to listen to your messages in order; you don’t have to listen to them at all. In seconds, these recordings are converted into typed text. They show up as e-mail messages or text messages on your cellphone.