Nokia provides telecom equipment and services that are used to build wireless and fixed-line networks, operating in four segments. The firm's mobile networks segment, which sells equipment and services to telecom carriers to power public wireless networks, is its largest, followed closely by network infrastructure. Network infrastructure focuses on fixed networks, including infrastructure, solutions, and components for IP networks, optical networks, and submarine networks. Cloud and network services is a nascent segment catering to enterprises with "as-a-service" platforms. Nokia also has a sizable research division and patent business where the firm licenses technology used by handset providers, consumer electronics firms, and other firms making electronic and Internet of Things products.