GLOSSARY GL-17
primary rate
interface (PRI)
private network
processor data
module (PDM)
protocol
discriminator
public network
pull-in range
pulse-amplitude
modulation
(PAM)
pulse-code
modulation
(PCM)
Q.920 and
Q.921
Q.930 and
Q.931
Q
recommendations
raw data
remote frame
alarm (RFA)
A standard Integrated Services Digital Network (ISDN) frame format that
specifies the protocol used between two or more communications systems. PRI
runs at 1.544M bps and, as used in North America, provides 23 64K-bps B-
channels (voice or data) and one 64K-bps D-channel (signaling). The D-channel
is the 24th channel of the interface and contains multiplexed signaling
information for the other 23 channels.
A network used exclusively for handling the telecommunications needs of a
particular multilocation customer.
A device that provides an RS-232C data circuit-terminating equipment (DCE)
interface for connecting to data terminals, applications processors (APs), and
host computers; and provides a Digital Communications Protocol (DCP)
interface for connection to a communications system. See also modular
processor data module.
The first part of every Integrated Services Digital Network (ISDN) message. The
protocol discriminator serves to identify the function — either call control or
maintenance — for that message.
A network that is commonly accessible for local or long-distance calling.
The range of frequencies from which the switch-clock oscillator can establish
synchronization.
A modulation technique in which an analog signal, such as speech, modulates a
carrier signal consisting of a series of precisely timed pulses of equal amplitude.
See also pulse-code modulation.
An extension of pulse-amplitude modulation (PAM) in which carrier-signal
pulses modulated by an analog signal, such as speech, are quantized and encoded
to a digital, usually binary, format. See also pulse-amplitude modulation.
The level-2 (link-layer) specification for use in an Integrated Services Digital
Network (ISDN) recommended by the CCITT for message transmission. See
also Q recommendations.
The D-channel level-3 (network-layer) specification for use in an Integrated
Services Digital Network (ISDN) recommended by the CCITT for basic
telecommunications call control. See also codepoint and D-channel.
Recommendations of the CCITT that affect an Integrated Services Digital
Network (ISDN). The Q.700 series defines signaling system number 7, which is
used for common-channel signaling across networks. Q.920 and Q.931 define a
digital-access signaling system for signaling between the customer’s equipment
and the network. See also CCITT, Q.920 and Q.921, and signaling system
number 7.
See unrestricted digital data.
The remote frame alarm (RFA), when received at the near end switch, indicates
that the far end switch is unable to frame up on the signal sent by the near end
(the end receiving this alarm). Also called the yellow alarm. See also loss of
frame alignment and loss of signal.