Radio has discovered a method to make money by selling advertisements, which is an indirect means of "charging" consumers by consuming some of their time. People who buy the promoted goods are eventually paying for the radio service, as the station includes the advertising expenses in the goods price. Satellite radio businesses, such as SirusXM, have recently begun charging a monthly subscription fee for commercial-free music streaming. However, in this case, the product is exclusive—the broadcast is only available to those who pay for a membership. Since radio is a way of earning revenue, the services are provided even by private companies. On the other hand, tornedo sirens, street lights, and lighthouses are not the source of revenue for the companies so they have no incentive to provide these services. Thus, these services are provided by the government and radio stations are not provided by the government.