Carrier integration with Google Voice may not be a Sprint exclusive for much longer, as Google product manager Vincent Paquet told CNET today that "we are having discussions with other carriers about this." It's the first time we've heard that integration with other carriers is even in the cards, although it isn't much to go by. The feature was introduced on Sprint in the US a year ago, and lets customers either use their current Sprint number for Google Voice or replace their carrier-provided number with one from Google. While users can port their existing phone number over to Google Voice from any carrier, the process costs $20 and usually involves canceling your current contract, which can carry an expensive early termination fee. While Paquet didn't offer any other details on who would get the feature next, it'll have to be one in the US, which is still the only country in which Google Voice is offered.