E Channel: Echo Channel
Echo Channel (E Channel) refers to the 64-Kbps ISDN circuit-switching control channel. The E channel was dropped in the 1988 ITU-TISDN specification. Now ISDN has only B channel, D channel, and H channel.

E&M Leads Signaling
E&M Leads Signaling is a type of signaling in telecommunications industry. It indicates the use of a handset that corresponds to the ear (receiving) and mouth (transmitting) component of a telephone.

E&M Signaling
E&M Signaling is a signaling method on a DS0 timeslot such that the signaling bits are used to indicate call states, such as on-hook, off-hook, alerting, and dial pulsing.

E&M: recEive and transMit
recEive and transMit (E&M), also known as Ear and Mouth, is the trunking arrangement generally used for two-way switch-to-switch or switch-to-network connections. E&M also is available on E1 and T1 digital interfaces.

E.123
E.123 refers to the ITU-R recommendation which is the notation for national and international telephone numbers recommendation. E.123 defines a standard way to write telephone numbers, email addresses, and web addresses.

E.164
E.164 refers to an ITU- recommendation that defines the international telecommunication numbering plan and telephone number format used for the PSTN and some other data networks. E.164 numbers can have a maximum of 15 digits. It is an evolution of standard telephone numbers.

E-2
E-2 refers to the European Digital Signal 2 which is the European standard for digital physical interface at 8.448 Mbps.

E-4
E-4 refers to the European Digital Signal 4 which is the European standard for digital physical interface at 139.264 Mbps.

E911 Service
E911 Service, short for Enhanced 911 Service, is a North American telephone network (NANP) feature of the 911 (or basic 911) emergency calling system which can automatically report the telephone number and location of 911 calls made from wireline phones.

EBAF: Extended Bellcore AMA Format
Extended Bellcore AMA Format (EBAF), also known as Enhanced BAF, is an update to the BAF, which is a system of abstract syntax and semantics that supports coding of Automatic Message Accounting (AMA) data into records. The main difference between the BAF and EBAF is that EBAF is more flexible and can be used easier, as the BAF uses a defined structure for storing data. The EBAF can append other information to the end of an AMA record, and this makes it more flexible.

EC: Echo Canceler
Echo Canceler (EC) is a device in telephony system for connection to a two-way telephone circuit to attenuate echo signals in one direction caused by signals in the other direction.

Echo Cancellation
Echo Cancellation is a method for removing unwanted signals from the main transmitted telephone voice signal.

ECSA: Exchange Carriers Standards Association
Exchange Carriers Standards Association (ECSA), now called ATIS (Alliance for Telecommunications Industry Solutions), is a standards body that developing telecommunications standards, operating procedures and guidelines through its sponsored committees and forums.

EDFA: Erbium-Doped Fiber Amplifier
Erbium-Doped Fiber Amplifier (EDFA), also called optical amplifier or an erbium amplifier, is an optical or IR repeater that amplifies a modulated laser beam directly, without opto-electronic and electro-optical conversion. The device uses a short length of optical fiber doped with the rare-earth element erbium. When the signal-carrying laser beams pass through this fiber, external energy is applied, usually at IR wavelengths. This so-called pumping excites the atoms in the erbium-doped section of optical fiber, increasing the intensity of the laser beams passing through. The beams emerging from the EDFA retain all of their original modulation characteristics, but are brighter than the input beams.

EDP: Event Detection Point
Event Detection Point (EDP), a term in Intelligent Network (IN), is a dynamically armed detection point. This will be armed by the SCF (Service Control Function) within the context of an IN service. EDP has two modes: 1) EDP-N (Event Detection Point-Notification) - this is dynamically armed and when triggered, the event is reported, however, processing is not suspended.
2) EDP-R (Event Detection Point - Request) - this is dynamically armed and when triggered, will suspend call processing. The SSF then waits for instructions from the SCF.

Effective Input NoiseTemperature
Effective input noise temperature is the source noise temperature in a two-port network or amplifier that will result in the same output noise power, when connected to a noise-free network or amplifier, as that of the actual network of amplifier connected to a noise-free source.

EIA/TIA-232
EIA/TIA-232, formerly called RS-232, is the common physical layer interface standard, developed by EIA and TIA. EIA/TIA-232 supports unbalanced circuits at signal speeds of up to 64 kbps, which closely resembles the V.24 specification.

EIA/TIA-449
EIA/TIA-449, formerly called RS-449, is a popular physical layer interface developed by EIA and TIA. EIA/TIA-449, essentially, is a faster (up to 2 Mbps) version of EIA/TIA-232 capable of longer cable runs.

EIA/TIA-586
EIA/TIA-586 is a standard developed by EIA and TIA that describes the characteristics and applications for various grades of UTP cabling.

EIA-232
EIA-232, a popular physical layer interface also known as RS-232 or TIA-232, is a standard for serial binary data interconnection between a DTE (Data terminal equipment) and a DCE (Data communication equipment). It is commonly used in computer serial ports. A similar ITU-T standard is V.24.

EIA-422
EIA-422, also known as RS-422 or TIA-422, is the balanced electrical implementation of EIA/TIA-449 for high-speed data transmission. Now referred to collectively with EIA-423 as EIA-530, it provides for data transmission, using balanced or differential signaling, with unidirectional/non-reversible, terminated or non-terminated transmission lines, point-to-point, or multi-drop.

EIA-423
EIA-423, also known as RS-423 or TIA-423, is the unbalanced electrical implementation of EIA/TIA-449 for EIA/TIA-232 compatibility.

EIA-449
EIA-449, also known as RS-449 or TIA-449, specifiecs the functional and mechanical characteristics of the interface between data terminal equipment and data communications equipment. The electrical signalling standards intended for use with RS 449 are RS-422 for balanced signals, and RS-423 for the unbalanced signals, with data rates up to 2,000,000 bits per second. The standard specified two D-subminiature connectors with 37 and 9 pins for the primary and secondary data circuits.

EIA-485
EIA-485, formerly known as RS-485 or RS485, is a physical layer electrical specification of a two-wire, half-duplex, multipoint serial connection. The standard specifies a differential form of signalling. The difference between the wires’ voltages is what conveys the data. One polarity of voltage indicates a logic 1 level, the reverse polarity indicates logic 0.

EIA-530
EIA-530, also known as RS-530 or TIA-530, is a balanced serial interface standard that generally uses a 25-pin connector. The specification defines the cable between the DTE and DCE devices. It is a replacement for EIA-449, which uses 37-pin connector. EIA-530 refers to two electrical implementations of EIA/TIA-449: RS-422 for balanced transmission and RS-423 for unbalanced transmission.

E-ISUP: Extended-ISUP
Extended-ISUP, originally a subset of Q.761 ISUP, is expanding in to a superset of ITU and ANSI ISUP. In addition, it supports the delivery of SDP parameters via generic digits. E-ISUP runs over IP and therefore uses IP addresses instead of point codes.

Eligible Telecommunications Carrier
Eligible telecommunications carrier refers to the company that provides telecommunication services in the United State.

E-Link: Extended Link
SS7 Extended link (E-link) connects an SSP to an alternate STP. E-links provide an alternate signaling path if an SSP's "home" STP cannot be reached via an "A" link. "E" links are not usually provisioned unless the benefit of a marginally higher degree of reliability justifies the added expense.

Embedded Operations Channel
Embedded Operations Channel refers to a channel provided on telecommunications facilities to support administration and maintenance

En-Block Signaling
En-block Signaling is the method in which the address digits are encoded into blocks for onward transmission. Note that the blocks of code contain all the address information required to route the call to its destination.

End-of-Pulse Signal
End-of-pulse Signal is an address signal sent in the forward direction to indicate there are no more address signals to follow.

End-of-Selection Signal
End-of-selection signal is a signal sent in the backward direction to indicate the successful completion of the call set-up process. It can also be used to indicate an unsuccessful termination of the call set-up process, and that may contain information on the called party's line condition.

EPON: Ethernet Passive Optical Network
Ethernet Passive Optical Network (EPON) is a point to multipoint network topology implemented with passive optical splitters, along with optical fiber PMDs that support this topology. EPON is based upon a mechanism named MPCP (Multi-Point Control Protocol), which uses messages, state machines, and timers, to control access to a P2MP topology. At the basis of the EPON/MPCP protocol lies the P2P Emulation Sublayer, which makes an underlying P2MP network appear as a collection of point to point links to the higher protocol layers (at and above the MAC Client). It achieves this by prepending a Logical Link Identification (LLID) to the beginning of each packet, replacing two octets of the preamble. In addition, a mechanism for network Operations, Administration and Maintenance (OAM) is included to facilitate network operation and troubleshooting.

Equal Access
Equal Access refers to the AT&T Divestiture - 1982 Modified Final Judgement (MFJ), which is the provision of one-plus capability to interLATA competitors of AT&T. The MFJ and the FCC require local exchange carriers to provide equal access and customers should be able to reach the carrier of their choice by dialing 1 + the long-distance number. Equal Access may also refer to a more generic concept under which the BOCs must provide access services to AT&T's competitors that are equivalent to those provided to AT&T.

Equipment Room
Equipment Room is the facility that houses building telecommunications systems such as Servers, PBXs, and mechanical terminations of the telecomm wiring system. In most of the cases, it is different than a wiring closet due to the complexity of the components it contains. But equipment Room nonetheless may take the place of a building's wiring closet or it may be a separate entity.

ERC: Easily Recognizable Code
Easily Recognizable Code (ERC) is a part of a North American telephone number in the area code position that has the pattern NXX, where N=2...9 and XX = 00, 22, 33, ... 88, For example, 800, 877, 900 and 700.

Erlang
Erlang is a measure of traffic load on a telephone line in 60 minutes blocks. The figure is calculated as a rate at which calls arrive divided by the rate at which they are completed.

Erlang Unit
Erlang Unit is a statistical measure of telecommunications traffic used in telephony. It is named after the Danish telephone engineer A. K. Erlang, the originator of queueing theory.

ESF: Extended Super-Frame
Extended Super Frame (ESF), sometimes called D5 framing, is a T1 framing standard that consists of 24 frames of 192 bits each, with the 193rd bit providing timing and other functions. Preferred over its predecessor, Super Frame, because it includes a Cyclic Redundancy Check and bandwidth for a data link channel (used to pass out-of-band data between equipment).

ESN: Electronic Switched Network
Electronic Switched Network (ESN) refers to a network that uses electronic switches to direct telecommunications traffic.

ESS: Electronics Switching System
Electronics Switching System (ESS), an AT&T/Lucent term, refers to switching systems using stored programs to electronically switch telecommunication information. A 5ESS is a digital central office for end office applications. A 4ESS is its digital central office for toll center applications.

ETB: End of Transmission Block Character
End of Transmission Block Character (ETB) refers to a transmission control character used to indicate the end of a transmission block of data when data is divided into such blocks for transmission purposes.

EURESCOM: European Institute for Research and Strategic Studies in Telecommunications
European Institute for Research and Strategic Studies in Telecommunications (EURESCOM) is the leading organization for collaborative R&D in telecommunications. EURESCOM provides efficient management of research projects and programmes for member companies and other clients.

Eutelsat
Eutelsat is inter-governmental organization founded in 1983 with the launch of Eutelsat 1. Eutelsat aims to provide and operate a space segment for public intra-European international telecommunications services. The segment is also used to meet domestic needs by offering leased capacity, primarily for television. UK and France are the main shareholders.

Even Parity
Even Parity is one of the parity processes for error checking, which indicates that the total number of ones in the information data stream plus the parity bit equals to an even number.

Exchange
Exchange refers to a component of telecommunications network that is equivalent to the following terms: "office", "Central Office", "telephone switch", "telephone exchange", or "wire center". An exchange can be used as (1) Local exchange, (2) toll (trunk) exchange, or (3) gateway exchange.

Exchange Carrier
Exchange Carrier, also known as local exchange carrier(LEC), refers to a local telephone company that provides the telephone services to residents and business. In the United States, as the result of 1984 divestiture of then regulated monopoly carrier AT&T, wireline telephone companies are divided into two categories: long distance, also called inter-exchange carrier, or IXCs, and local carrier, also called local exchange carrier, or LECs. According to the Federal Communications Commission, local phone calls are defined as calls originating and terminating within a LATA (local access and transport area).

Expandor
Expandor is the function or process to perform the inverse function of a compressor ( at the receiver).

EXZ: Excessive Zeros
Excessive Zeros (EXZ or EZ) is a type of error event in DS1(T1)/E1 and DS3(T3)/E3 interfaces when an AMI-coded signal is the occurrence of more than fifteen contiguous zeroes. For a B8ZS coded signal, the defect occurs when more than seven contiguous zeroes are detected.