Sprint customers who visit the Google Voice website can hit the Enable button, which allows them to make calls from the Web using their Sprint phone number as their ID as well as linking the Google Voice number to the Sprint service itself and using Google's text-transcripted voicemail as the default. Take note that if you do switch to Google for your voicemail needs, you will lose all messages saved in the Sprint voicemail system.
Sprint announced last month that all of its customers will be able to turn their phone numbers into full-service Google Voice numbers, integrating all the included services without having to port them or take on a second phone number. Google Voice integration means Sprint customers' current number will be able to ring on multiple phones by default, and Google Voice's voicemail services will replace the Sprint voicemail interface. Sprint customers that already have separate Google Voice numbers will be able to switch to it as their primary phone number, and all of the Google Voice features will no longer require the dedicated app.