Porting an existing number into Google Voice seems simple, but the process can quickly turn complicated. The reason: Once you port your existing mobile number into Google Voice, your current mobile service plan will be cancelled. You'll have to call your carrier and get it to restart your service and assign a new number to your phone (even though you won't be giving that number out, it still has to exist -- otherwise, your phone won't work and Google Voice won't have anywhere to actually forward your calls).

Google on making the process as smooth as possible, but you should be ready for a hassle. As , mobile carriers aren't always equipped (translation: competent) at handling this type of request, and -- unless you're planning to cancel your current service plan and switch carriers right now anyway -- you may be in for a bumpy ride.

Once your primary phone number is connected to Google Voice, you can use the service to place unlimited calls that'll come from your number -- without having to actually use your cell phone. By utilizing the Google Voice website or , you can have the service place a call to any U.S. number and route it to a landline or VOIP line for you to pick up (you can even and make/receive calls there). The person on the other line will still see the call as coming from your number, and you won't have to use your cell phone's minutes to talk.