Safari Books Online is a digital library providing on-demand subscription access to thousands of learning resources.
The telecommunications industry is dominated by organizations that are among the 100 largest companies in the United States. However, technological innovations have enabled companies such as Apple, Google, Netflix, and Amazon to encroach on services that were formerly the exclusive domain of traditional telephone and cable TV operators. Mobile operators, cable Multiple System Operators (MSOs), and Internet companies now vie with one another for revenue from mobile, Voice over Internet Protocol (VoIP), cloud, and entertainment services.
The two largest traditional telephone companies in the United States are AT&T, Inc, and Verizon Communications. They each offer home telephone service, mobile services, business long distance, global data networking, business telephone systems, and cloud computing. Their data services are supported by hundreds of data centers worldwide.