 Both IPTV and OTT use the Internet protocol over a packet-switched network to transmit data, but IPTV operates in a closed system—a dedicated, managed network controlled by the local cable, satellite, telephone, or fiber-optic company.In its simplest form, IPTV simply replaces traditional circuit switched analog or digital television channels with digital channels which happen to use packet-switched transmission.In both the old and new systems, subscribers have set-top boxes or other customer-premises equipment that communicates directly over company-owned or dedicated leased lines with central-office servers.