Multi Tech Equipment MTA128ST - Manual (Page 57)

Glossary
57
off-hook —The condition of a device that has accessed
a phone line (with or without using the line). In
modem use, this is equivalent to a telephone handset
being picked up. Dialing and transmission are allowed,
but incoming calls are not answered.
on-demand dialing —A cost-saving feature of ISDN
that sets up, transfers, and then closes a call only when
the ISDN device detects a data packet addressed to
the remote network, but will not perform
setup/transfers ofjust administrative (non-user data)
packets.
out-of-band signaling —A system that uses a separate
communications channel or frequency outside the
voice band for signaling. Modern systems use a
separate channel, either TDM or virtual. SS7 uses
messages for signaling that are carried on
signaling links distinct from voice channels. ISDN
uses messages for signaling that are carried on the
D-channel distinct from the voice carried on the B-
channels. Frame Relay and ATM use messages that
are carried on a separate virtual connection reserved
for signaling.
on-hook —The condition of a device which has not
accessed a phone line. In modem use, this is
equivalent to a telephone handset that has not been
picked up. In other words, it can receive an incoming
call.
P
packet data
—Packet-mode calls.
packet mode —The switching of chunks of information
for different users using statistical multiplexing to send
them over the same transmission facility. ISDN
packet mode capabilities are based on the ITU-TSS
Recommendation X.25 procedures.
PAP (Password Authentication Protocol): (RFC 1334)
parity bit —An extra bit attached to each byte of
sync—hronous data used to detect errors in
transmission.
PBX
(private branch exchange)—A telephone
exchange located on the customer’s premises. The
PBX provides a circuit switching facility for tlephone
extension lines within the building, and access to the
public telephone network. See also exchange.
P-channel (PCHAN)—The ISDN physical channel
identification; contrast logical channel or virtual
channel.
PDN (public data network)—A packet-switched
network that is available to the public for individual
(subscriber) use. Typically, controlled by a
government or a national monopoly.
port —A location for input or output data exchange.
Computers, muxes, etc. have ports for various
purposes.
PPP
(Point to Point Protocol)—A protocol that lets a
computer user access a TCP/IP address using an
ISDN terminal adapter or a highspeed modem over a
standard telephone line.
PRI
(Primary Rate Interface)—One
of two forms of ISDN service. PRI provides 23 64 Kbps
B-channels for video, voice or data, and one 64 Kbps
D-channel for control
information. Usually used to connect high-cpacity CPE,
such as PBXs, to the network. Also called 23B+D in the U.S.
and 30B+D in Europe.) See also ISDN and BRI.
primitive —An abstract representation of interaction accross
the access points indicating that information is being passed
between the service user and the service provider. The OSI
Reference Model defines four types of primitives: Request,
Indication, Response and Confirm.
PSTN (public switched telephone network)—The group of
circuit-switching voice carriers, which are commonly used as
analog data communications services. A worldwide public
voice telephone network that is used as a
telecommunications medium for the transmission of voice,
data and other information.
pulse dialing —One of two methods of dialing a telephone,
usually associated with rotary-dial phones. Compare with
tone dialing. PVC
(permanent virtual circuit)—A connection
between two endpoints dedicated to a single user. In ISDN,
PVCs are established by network administration and are
held for as long as the user subscribes to the service.
Q
Q.921 —The ITU-T recommendation for user-network
interface layer 2 specifications for D-channel signaling.
Similar to LAPD. See also ISDN.
Q.931
—The ITU-T recommendation for user-network
interface layer 3 specifications for D-channel signalling.
See also ISDN.
R
R reference point
—Establishes the boundary between non-
ISDN compatible equipment (TE-2) and the IDN network. TAs
are used to convert the communication protocol used by
the non-ISDN termnials to the desired BRI or PRI
protocol. Non-ISDN (TE2) terminal equipment connects to
IDN at the R-Reference point with a TA. (This interface may
follow the RS232 or V.35 specification.) Also called the R
interface. (Contrast S reference point.)
RAM (random access memory)—A computer’s primary
workspace. All data must be stored in RAM (even for a short
while), before software can use the processor to manipulate
the data. Before a PC can do anything useful it must move
programs from disk to RAM. When you turn it off, all
information in RAM is lost.
reference point —A connection point between ISDN
equipment classes (rather than the specific protocol of the
interconnection). Can include R, S, T, and U reference points.
RFC (Request for Comments)—Name for the IETF document
that provides internet standards.
RJ-11
—An industry standard interface used for connecting
a telephone to a modular wall outlet; comes in 4-and 6-wire
packages. RJ-45—An 8-wire modular connector for voice and
data circuits. RPOA (recognized private operating
agency)—A corporation, private or government-controlled,
that provides telecommunications services. RPOAs, such as
AT&T, participate as non-voting members in the ITU-T.
RS-232
—An EIA/TIA standard for a serial interface between
computers and peripheral devices (modem, mouse, etc.).
It uses a 25-pin DB-25, or a 9-pin DB-9 connector. The RS-
232 standard defines the purposes, electrical characteristics
and timing of the signals for each of the 25 lines. Similar to
the ITU-T V.24 standard.