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Glossary
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connect the call to a different channel. Drop-and-insert configurations
provide the ability to access an operator or another call.
DSL
Digital Subscriber Loop
E-1
Another name given to the CEPT digital telephony format devised by
the CCITT that carries data at the rate of 2.048 Mbps (DS-1 level).
event
An unsolicited communication from a hardware device to an
operating system, application, or driver. Events are generally attention-
getting messages, allowing a process to know when a task is complete
or when an external event occurs.
glare
When an inbound call arrives while an outbound call is in the
process of being setup, a “glare” condition occurs. Unless the protocol
specifies otherwise, the incoming call takes precedence over the
outbound call.
IA5
International Alphabet No. 5 (defined by CCITT)
IE
Information Element
Information Element (IE)
Used by the ISDN (Integrated Services Digital
Network) protocol to transfer information. Each IE transfers
information in a standard format defined by CCITT standard Q.931.
Integrated Services Digital Network (ISDN)
A collection of standards for
defining interfaces and operation of digital switching equipment for
voice and data transmissions.
ISDN
Integrated Services Digital Network
LAPB
Link Access Protocol-Balanced
LAPD
Link Access Protocol on the D channel
line device handle
A numerical reference to a device, obtained when the
device is opened. This handle is used for all operations on that device.
Non-Call Associated Signaling (NCAS)
allows users to communicate by
user-to-user signaling without setting up a circuit-switched connection
(this signal does not occupy B channel bandwidth). A temporary
signaling connection is established and cleared in a manner similar to
the control of a circuit-switch connection. Since NCAS calls are not
associated with any B channel, applications receive and transmit NCAS
calls on the D channel line device. Once the NCAS connection is