You connect to the Internet telecommunications infrastructure by using the services of an Internet service provider (ISP). ISPs can provide both dial-up connectivity for occasional connection to the Internet or dedicated digital lines for high-speed continuous 24-hour connectivity.
As discussed previously, there are a number of different types of organizations that make up the Internet telecommunications infrastructure. These range from telephone companies to specialized commercial enterprises. The Internet infrastructure is layered, with traffic from the ISPs in the lower layers funneled up to the national backbone service providers referred to as NSPs.
The separation between the backbone and regional network layers of the current infrastructure is blurring, as more regional areas connect directly to each other through the increasing number of ISPs in each region of the United States.