Network Security Information Sharing Act of 2019 This bill establishes a program to share information regarding supply chain security risks with trusted providers of advanced communications service and trusted suppliers of communications equipment or services. Under the program, the Department of Homeland Security, in cooperation with certain agencies, must (1) share information with trusted providers of advanced communications service and trusted suppliers of communications equipment or services, (2) engage in particular with trusted providers and suppliers that are small businesses or that primarily serve rural areas, and (3) submit a plan for declassifying material and expediting the provision of security clearances to aid in sharing information about supply chain security risks. The bill also requires the Federal Communications Commission to appoint at least one member, who shall represent the interests of the public and consumers, to the Communications Security, Reliability, and Interoperability Council.