carrier
Google Voice’s Additional Charges To Sprint Call Recipients
Apparently the charges are being incurred because the number that is used by Google Voice is being treated as a landline number by the national number database so when callers receive the call by Google Voice it ends up eating into their anytime minutes which could lead to additional fees.
Sprint has noted that there is no way of changing this at the moment and are instead encouraging users to stick with their Sprint number as their primary number instead. I guess there’s really no such thing as a free lunch.