Sprint makes it easy to use Google Voice.

Little by little, Google Voice has encroached on U.S. mobile operators' turf, most recently offering to port a subscriber's carrier-assigned cell phone number for use with Google Voice's service. But now for one carrier, potential friction has given way to partnership.

Sprint and Google announced today deep integration with Google Voice that lets subscribers use their Sprint phone number as a Google Voice number to access the service's features. These include transcribed visual voice mail (manage voice messages as you would your e-mail), call forwarding (calls ring through on your cell phone, home phone, office phone, Gmail inbox, and so on), custom voice mail greetings, and competitive international calling rates, among many more offerings.

Google and Sprint have been in talks for about a year, Vincent Paquet, senior product manager for Google Voice, told CNET. "We always felt that the ultimate simplicity would be to just use [Google Voice] with your mobile phone," Paquet said. He declined to comment on details pertaining to the deal, and questions about Google's deals with other carriers.

Benefits of Google Voice Anyone could sign up for the free Google Voice service before, but today's agreement has a few notable benefits. First, Sprint simplifies getting on board with Google Voice. Previously, Google Voice users on any carrier needed to walk through a number of steps to either get a new Google Voice number, port their existing number, or let Google handle just the voice mail. The results could be confusing, with friends often collecting multiple phone numbers for a contact, depending on a several factors, including if the Google Voice user has a feature phone, or uses a Google Voice mobile app or Web-optimized site from a smartphone.

As a second benefit, all Google Voice calls will originate from the same single number--the one first issued by Sprint. Third, if you enable Google Voice, the service will replace Sprint's voice mailbox on your phone, so dialing "1" from the handset dials up your Google Voice message inbox. There is no extra set-up required. Fourth, Sprint smartphones get most Google Voice features without requiring a mobile app.

Texting is one exception to this last point, however. Sprint's rates and plans still apply for messages sent from the phone's default texting program, but Google Voice texts will remain free to the United States and Canada if you send them from the Web or from a Google Voice smartphone app.

Prepaid phones and MVNOs that ride on Sprint's network--like Boost Mobile and Virgin Mobile--are ineligible for the Sprint/Google Voice combo.

Signing up There are several ways to enable Google Voice on a Sprint phone. When new users sign up online, Google Voice will recognize Sprint numbers before guiding you through the setup process. Existing users who log in will receive a prompt to switch to the Sprint number. This is optional, of course.

We look forward to testing the service out in the coming days, and we'll likely hear much more from Google and Sprint this week at CTIA. Check back with CNET for more insights, and feel free to leave your own in the comments.