quality SO long as it is operating within bandwidth and error rate performance specification parameters. Sound Fidelity-Speech Quality References to sound fidelity in- clude terms like FM Quality and CD Quality. Assessing sound quality tends to be almost totally subjective. However, the ability of a transmission channel or other form of media to carry sound PRACTICAL IP AND TELECOM FOR BROADCAST ENGINEERING AND OPERATIONS can be measured and expressed objectively in terms of frequency response, signal-to-noise ratio, distortion, and, in the case of stereo or multiple channel sound transmission, separation. Speech quality is a telephone term usually expressed in terms of compliance with a particular standard. The most commonly used reference is ITU Rec. G.711, defining a toll quality speech codec. Adopted many years ago, it is, and has been, the benchmark for speech quality in international telephony that most succeeding codecs have been measured against. Essentially, it relies on an approach where the speech signal is sampled at an 8Khz rate and quantized to 8-bits. The output of the encoder is a 64Kbs stream, matching the 64Kbs channel rate provided by the public switched telephone network. G.711 includes two encoding laws. The Mu- Law version is used in Japan and North America. The A-Law version is used in the rest of the world. ITU Rec. J.52 covers transmission of high-quality sound-program signals using one, two, or three 64 Kbs channels per mono signal, and/or up to six per stereo signal. The system described in J.52 enables transport of sound signals using new coding techniques included in ISO11172-3. Service Service is the right to use network equipment and facilities. Many people confuse services and facilities. Still others say prod- uct when they should say service, and still others confuse technol- ogy and methodology with services. For example, a DS3 or E3 is a facility, not a service or product. Telephone companies provide services, not products. The only products they make are phone bills. ISDN, ATM