Users can now port their existing cell phone number to Google Voice, making it easier to switch all of your existing friends and contacts over to your Google Voice number. Porting your number to Google Voice costs $20 and comes with a few words of warning.
First and most importantly porting your cell phone number to Google may cancel your cell phone contract, resulting in an early termination fee and a long and headache inducing process. If you want to port your existing number to Google Voice you should contact your cell phone carrier first to get a note placed on your account so that you can call them back and get a new number after the port is completed. For more details check out the Google Voice Help Center.
Even if you do this you may end up with an experience similar to that of David Kravets who writes on Wired.com that “Google Voice Porting equals LSD Trip Gone Awry.”