n and physical proximity of the service provider's switching and transmission systems. Table 4-7 summarizes the major technologies used in switching and transmission facilities and shows framing, packet, bandwidth, and data rate characteristics. View this summary and the table as an introduction to more details about facilities and services covered in the next chapter. Broadcast Industry Services Broadcast services are something of a special case. From the early days of radio, AT&T built transmission facilities to support broadcast networks. Splitters in the form of resistive networks or transformers, amplifiers, and equalizers enabled multipoint connections from the network source to all the radio stations making up the network. By the time television networks required distribution facilities, AT&T's network contained significant broadband capacity in the form of frequency division multiplexing over microwave radio and coax transmission backbone. Carrying television audio and video became a matter of interfacing the frequency division hierarchy in much of the same conceptual ways it's done today with digital networks. Satellite transmission, with its lower cost and reliability advantages, quickly caught on and replaced AT&T terrestrial services for national network distribution. Services in a local area used similar equipment, but the transmission media for audio was a standard copper twisted pair wire like that used in telephone service. Television program transmission was mainly on microwave radio or baseband transmission on 124-Ohm balanced coaxial cable. 4 NETWORK TECHNOLOGY AND METHODOLOGY With the advent of digital networks, so-called encoding and decod- ing equipment was designed to convert analog program signals into digital signals and interface them to the digital network. Typical radio program material requires several hundred kilobits of band- width depending on the nature of the signals and number of program channels. Similar equipment carries NTSC or PAL program material on an E3 or T3 transmission