Communications System Owner Manual

GL-20 GLOSSARY
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protocol converter (PC) A device consisting of hardware, software, or a combination of both, that
allows two systems, each using a different protocol, to communicate and
exchange messages with each other.
public network A network that is commonly accessible for local or long-distance calling.
pulse-amplitude
modulation (PAM)
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.
pulse-code modulation
(PCM)
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.
PVC See permanent virtual circuit.
Q recommendations 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.
Q.920 and Q.921 The level-2 (data-link layer) specification for use in an Integrated Services
Digital Network (ISDN) recommended by the CCITT for message
transmission. See also Q recommendations.
Q.930 and Q.931 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.
remote access trunk A telecommunications channel used by an authorized user to gain access
to the communications system.
restricted [channels] Restricted channels are channels over which no all-zero bytes can be
transmitted. The line equipment transmitters on restricted channels use
ZCS line coding.
RNX The location code for a private-network communications system, where R
equals any digit 2 through 9 except the assigned call-detail recording
(CDR) account code prefix, N equals any digit 2 through 9, and X equals
any digit 0 through 9.
robbed-bit signaling Digital signal level-1 (DS1) signaling in which up to eight kbps from each
of the 24 64-kbps channels are used for signaling in every sixth frame.
The least-significant bit of each 8-bit sample is replaced by a signaling bit.
Also called DS1 robbed-bit signaling.