and the electromagnetic spectrum T-1, which offers 1.544Mbps, is a North American standard. T-1 is used in the United States and in some overseas territories, such as South Korea and Hong Kong. E-1, which provides a total of 2.048Mbps, is specified by the ITU. It is the interna- tional standard used throughout Europe, Africa, most of Asia-Pacific, the Middle East, and Latin America. J-carrier is the Japanese standard, and J-1 offers 1.544Mbps. Not every office or application requires the total capacity of T-1, E-1, or J-1. In some places, it is possible to subscribe to fractional services, which means you sub- scribe to bundles of channels that offer less than the full rate. Fractional services are normally provided in bundles of 4, SO you can subscribe to 4 channels, 8 chan- nels, 12 channels, and so on. Fractional services are also referred to as n X 56Kbps/ 64Kbps in the T-carrier system and n X 64Kbps under E-carrier. Fractional services are by no means offered ubiquitously. Much depends on the regulations; also, DSL, where available, has replaced the need for fractional services. High-bandwidth facilities include T-3, E-3, and J-3. T-3 offers 45Mbps, E-3 offers 34Mbps, and J-3 supports 32Mbps. (T-, E-, and J-carrier services are dis- cussed in more detail in Chapter 4.) The Electromagnetic Spectrum and Bandwidth Broadband The future hierarchy rests on broadband capacities, and broadband can be defined in different ways, depending on what part of the industry you're talking about. Technically speaking, the ITU has defined broadband as accommodating anything over 2Mbps. But this definition was created in the 1970s, when 2Mbps seemed like a remarkable capacity. The Impact of Fiber Optics on Bandwidth So far this chapter has used a lot of bits-per-second measurements. It can be difficult to grasp what these measurements really mean. So, here's a real-world example. Today, fiber optics very easily accommodates 10Gbps (i.e., 10 billion bits per second). But what does that really mean? At 10Gbps you'd be able to tr