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E1

See CEPT E1.

E&M

E lead and M lead; a telephone signaling system used between two switches that uses two wires called the E lead and the M lead. In digital E&M signaling, the A bits and B bits are used.

echo cancellation

An algorithm for removing a portion of the received signal determined to be echo by comparison with the output signal.

ECM

Error Correction Mode; for fax transmission, a T.30 option which can be used to correct transmission errors. The fax receiver uses checksum information to verify that the image data received matches what was transmitted. If it does not match, the receiver can request retransmission of a portion of the data. This option is useful when noisy telephone line conditions are expected.

ELS

See enhanced loop start hybrid (ELS).

encoding

Any of several compression techniques for digitizing and compressing data.

end system

An application that generates the content to be sent in RTP packets and/or consumes the content of received RTP packets. An end system can act as one or more synchronization sources in a particular RTP session. See also RTP, RTP session.

endpoint

An originating or terminating device or entity.

end-to-end layers

In the OSI layering model, layers above layer 3 (the network layer). These layers describe how information is exchanged and delivered end-to-end. They also define process-to-process communication, and describe application-independent user services, user interfaces, and applications. See also International Organization for Standardization (ISO), network layer, Open System Interconnect (OSI).

energy detector

An algorithm for reporting the existence or nonexistence of signals and audio on a telephone line based on a set of qualifying parameters. Examines the in-band signal to distinguish between silence and energy.

enhanced loop start hybrid (ELS)

An NMS line interface hybrid that provides on-hook monitoring of a telephone line at normal audio levels. The enhanced loop start hybrid offers improved logging and better signal-to-noise detection than the standard loop start hybrid.

enhanced switching compliant

See MVIP Enhanced Switching Compliant device.

Entity ID

A unique value that identifies an application running on a host computer. Each application must select a unique Entity ID between 0x20 to 0x3F.

ESF

Extended SuperFrame; a framing format in the T1 environment. There are 24 separate 193 bit frames in an Extended Superframe. The 24 framing bits, one from each individual frame, are used to maintain synchronization in a manner similar to D4 framing, provide error checking, and provide a diagnostic channel. In-band signaling is employed using robbed-bit signaling. See also D4 framing, robbed-bit signaling, T1.

Ethernet

A local area network hardware, communication, and cabling standard. Ethernet is synonymous with 10 Base-T.

ETSI

European Telecommunication Standards Institute.

EUC protocols

EUropean digital Channel associated signaling protocols. A protocol family including special channel associated signaling protocols used in certain European countries. The protocols use two-bit line signaling, not as specified by CCITT, but as specified by national documents. The register signaling is either carried by in-band DTMF tones (not compelled) or by out-of-band decadic pulses. Also know as EuroCAS.

error macros

Macros used by service API functions to ensure consistent error handling across all CT Access services.

events

In CT Access, data structures that contain notification of certain conditions or state changes. Events can be sent from the hardware or from another software module to the application program. All events are represented as C data structures. The event structure contains information about the specific event, including a timestamp, associated CTA context, specific data, error codes, or reason codes. For example, when a voice play operation completes, a completion event is returned to the application. See also completion event, DONE event.

event consumer

Retrieves and processes published events.

event producer

Publishes events to a well-known location.

event queue

In CT Access, the single queue created by calling ctaCreateQueue where the application receives all of its events from the telephony hardware. NMS software is event-driven. CT Access provides functions to wait for and retrieve events from the event queue.

Exclusive Mode

One of two modes which determines how the AG ISDN TCP responds if the telephone network denies the AG ISDN TCP use of its default channel. The default channel is the B channel bound to the same CTA context as the ISDN TCP instance. In Exclusive Mode, the TCP aborts the call. See also Non-Exclusive Mode, default channel.

Fast Ethernet

An Ethernet specification that enables data transmission rates of 100 Mbit/s. Synonymous with 100 Base-T.