There are also a number of backbone and midlevel networks in other countries. Most western European countries have national networks that are attached to Ebone, the European Internet backbone. The infrastructure is still inefficient in some places, and connections between countries are often slow or of low quality. It is common for Internet traffic between countries in Europe to be routed through the U.S. backbone.
The availability of full Internet service varies by location. In this chapter, discussion of WAN connectivity is limited to telecommunication services available in the United States. For example, Integrated Services Digital Network (ISDN) service, which is a preferred service for Internet connectivity for small to medium-sized enterprises connecting to the Internet in the United States, can be prohibitively expensive for sites in other parts of the world.
For information about worldwide Internet connectivity, available telecommunication services, and ISPs, search the International Telecommunications Union Web server at: http://www.itu.ch. You can also contact public telecommunication carriers in your area for additional information.