Google Voice logo.There are few technologies that I’ve promoted as relentlessly as Google Voice. In several columns and in a video, I’ve lauded the service for transforming how I use my phone. Instead of having one number for your home phone, another for your office, and another for your mobile, Voice gives you a single phone number for everything. When someone calls me, the service rings all my phones (or any subset of phones, depending on a schedule I’ve set). Plus, you can even answer your phone in Gmail (which is really handy when you’re in a place with bad cell coverage but great Internet coverage).

But that’s not all! Voice transcribes my phone messages and e-mails me the text, freeing me from the scourge of voice mail. Even though these transcriptions are often hilariously inaccurate, it lets me get the gist of my calls in an instant. It also lets me respond to text messages from my computer, which is much easier than fumbling on a phone. And, finally, because the service offers free calls across the country and cheap calls overseas, it has breathed new life into my home phone, which mobile phones had long ago promised to kill off. Best of all, Google Voice is free.

Yet despite my fevered proselytizing, I’d be surprised if I’ve convinced all that many people to use Voice. For many years, Google Voice were open only by invitation. The service also took some time to add key features—like text messaging—and it’s gone through a few buggy periods. (The site was unbelievably slow just after the Google acquisition.) But the biggest shortcoming, by far, has been Voice’s lack of number portability. When you signed up, you had to pick a new Voice-enabled phone number. Since most of the service’s features only work when people call your Voice number directly, that meant you had to give all your friends and work contacts new digits. For most people, this was a nonstarter.

On Tuesday, Google fixed that lingering problem. If you pay Google $20, you can sign up for Voice with your existing mobile phone number. (You can find step-by-step instructions here.) Once you convert your cell number to a Voice number, it will get all the Google superpowers you’ve been missing, including voice-mail transcription and the ability to ring all your phones simultaneously. The catch is that the Voice conversion will require you to call up your cell provider, and if you aren’t careful, it may end up costing you an early termination fee. If you’re willing to put up with a string of potentially maddening interactions with customer-service reps, then I’d highly recommend making the switch to Voice immediately.

To see why porting your number to Google Voice could be an annoying process, you need to understand how the system works. Think of it as something like an old-timey phone operator. When someone calls your Voice number, Google routes the call through the Internet to your multiple phones. In order for you to receive calls, you need to have a service plan for each of your phones—that is, you still need a cell provider, and if you want to get calls at home, you’ll still need to pay for a landline.

That’s the complication in porting your mobile phone number to Voice. If you assign the number to Google without telling your mobile provider, then Verizon or AT&T will think you’re canceling your plan. If you’re under a contract, the phone company is going to charge you a fee for canceling early. Those fees can run into the hundreds of dollars depending on what kind of phone plan you have and how much time remains on your contract. (Verizon’s fee for smartphones is $350, and AT&T’s is $325.)