The Communications Sector is an integral component of the U.S. economy as it underlies the operations of all businesses, public safety organizations, and government. Over 25 years, the sector has evolved from predominantly a provider of voice services into a diverse, competitive, and interconnected industry using terrestrial, satellite, and wireless transmission systems. The transmission of these services has become interconnected; satellite, wireless, and wire-line providers depend on each other to carry and terminate their traffic and companies routinely share facilities and technology to ensure interoperability.

A majority of the Communications Sector is privately owned, requiring the Department to work closely with the private sector and its industry associations to identify infrastructure, assess and prioritize risks, develop protective programs, and measure program effectiveness.

• The Energy Sector provides power to run cellular towers, central offices, and other critical communications facilities
• The Information Technology Sector provides critical control systems and services, physical architecture and Internet infrastructure
• The Banking and Finance Sector relies on telecommunications for the transmission of transactions and operations of financial markets
• The Emergency Services Sector depends on telecommunications for directing resources, coordinating response, alerting the public, and receiving emergency 911 calls
• The Postal and Shipping Sector uses telecommunications for its control systems, tracking shipments, and regular communications requirements

• Government technologies akin to Global Positioning System (GPS)
• Telecommunication Service Priority (TSP) Circuits ID 
• Emergency Services – Public Safety Answering Points (PSAP), and Emergency Broadcast Services (EBS)
• Public Safety Answering Points (PSAPs) that are FCC registered
• Major switching centers 
• Major underwater cable landings 
• Telecommunications hotels 
• Network protection equipment (NPE)
• Line terminal equipment (LTE)
• Wavelength termination equipment
• Transmission line amplifiers
• Power-feed equipment
• Terrestrial city point-of-presence—a site with a collection of telecommunications equipment (usually modems, digital leased lines, and multi-protocol routers)