ii Telecommunication Reference Book 700 Acronyms & Terminologies iii Dedicated To my mother Because of whose struggle and sacrifice I am able to attain this position iv Preface After I completed the reference book on Internet, I realized that the task would remain incomplete if no similar effort is made with reference to telecommunication, as convergence of Internet to telecommunication media is occurring at very rapid pace that these two can not remain separated for long. A typical example is VOIP (Voice Over Internet Protocol). There is so much common between the two now that study of one will remain incomplete without the study of the other. This realization prompted me to compile a similar book on Telecommunication terminologies and acronyms. The book contains about 700 terms and acronyms and is organized in alphabetical order on the pattern of any dictionary. Each term has been presented in the form of a continuous paragraph for continuity purpose. Wherever necessary, bullet points have been used to describe features, types and characteristics. The terms and acronyms are not merely defined but are explained in detail. Any term/acronym used within each of the explanation is underlined so that the reader not only becomes aware but also registers the same in mind subconsciously. The reader will be able to study the related terms so underlined generally within the same book elsewhere. The book also describes, certain products, services and protocols, which are offered by various international organizations of the industry and have become world industry standards. All the terms have been presented without any changes or amendments as they were downloaded from highly authentic websites (Please refer to bibliography at the end). I am thankful to all my friends who assisted me in organizing this book, especially Mr. Naseemullah Malik, who designed its beautiful and meaningful cover. I hope this small effort will be appreciated. Ahmad Nadeem Syed [email protected] v Table of Contents A ........................................................................................................................................................... 1 B ........................................................................................................................................................... 9 C ......................................................................................................................................................... 17 D ......................................................................................................................................................... 30 E ......................................................................................................................................................... 51 F ......................................................................................................................................................... 60 G ......................................................................................................................................................... 75 H ......................................................................................................................................................... 83 I .......................................................................................................................................................... 90 J.......................................................................................................................................................... 94 K ......................................................................................................................................................... 95 L ......................................................................................................................................................... 96 M ...................................................................................................................................................... 103 N ....................................................................................................................................................... 110 O ....................................................................................................................................................... 115 P ....................................................................................................................................................... 124 Q ...................................................................................................................................................... 133 R ....................................................................................................................................................... 134 S........................................................................................................................................................ 142 T ....................................................................................................................................................... 161 U ....................................................................................................................................................... 170 V ....................................................................................................................................................... 174 W ...................................................................................................................................................... 180 X ....................................................................................................................................................... 188 Numbers & Signs ........................................................................................................................... 191 vi A A Access Access is simply being able to get to what you need. Data access is being able to get to (usually having permission to use) particular data on a computer. Web access means having a connection to the World Wide Web through an access provider or an online service provider such as America Online. For data access, access is usually specified as read-only access and read/write access. ACD An Automatic Call Distributor (ACD) is a telephone facility that manages incoming calls and handles them based on the number called and an associated database of handling instructions. Many companies offering sales and service support use ACDs to validate callers, make outgoing responses or calls, forward calls to the right party, allow callers to record messages, gather usage statistics, balance the use of phone lines, and provide other services. ACDs often provide some form of Automatic Customer/Caller Identification (ACIS) such as that provided by Direct Inward Dialing (DID), Dialed Number Identification Service (DNIS), or Automatic Number Identification (ANI). ACTS ACTS (Automatic Coin Telephone System) is a public coin-operated telephone service that completes a variety of phone calls, times the calls, and collects payment without the aid of an operator Adaptive Differential Pulse-Code Modulation Pl. see ADPCM ADPCM ADPCM (adaptive differential pulse-code modulation) is a technique for converting sound or analog information to binary information (a string of 0's and 1's) by taking frequent samples of the sound and expressing the value of the sampled sound modulation in binary terms. ADPCM is used to send sound on fiber- optic long-distance lines as well as to store sound along with text, images, and code on a CD-ROM ADSL ADSL (Asymmetric Digital Subscriber Line) is a technology for transmitting digital information at a high bandwidth on existing phone lines to homes and businesses. Unlike regular dialup phone service, ADSL provides continously-available, "always on" connection. ADSL is asymmetric in that it uses most of the channel to transmit downstream to the user and only a small part to receive information from the user. ADSL simultaneously accommodates analog (voice) information on the same line. 1 ADSL is generally offered at downstream data rates from 512 Kbps to about 6 Mbps. A form of ADSL, known as Universal ADSL or G.lite, has been approved as a standard by the ITU-TS. ADSL was specifically designed to exploit the one-way nature of most multimedia communication in which large amounts of information flow toward the user and only a small amount of interactive control information is returned. Several experiments with ADSL to real users began in 1996. In 1998, wide-scale installations began in several parts of the U.S. In 2000 and beyond, ADSL and other forms of DSL are expected to become generally available in urban areas. With ADSL (and other forms of DSL), telephone companies are competing with cable companies and their cable modem services. Also see Fast Guide to DSL. Advanced Intelligent Network Pl. see AIN AF AF (audio frequency) (also abbreviated af or a.f.) refers to alternating current (AC) having a frequency such that, if applied to a transducer such as a loudspeaker or headset, will produce acoustic waves within the range of human hearing. The AF range is generally considered to be from 20 Hz to 20,000 Hz. All telephone circuits operate with AF signals in a restricted range of approximately 200 Hz to 3000 Hz. A telephone-line modem is an AF device that converts binary digital data into analog signals that can be transmitted over the telephone circuit, and