Multi-Tech Systems MTA128NT - Manual (Page 63)

Glossary
MTA128ST/NT 63
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.
S
S reference point—Provides the connection between NT2 equip-
ment and the TA or TE-1. Can provide both primary and basic rate
services. Also called the S-interface. (Contrast R-reference point.)
SAP (service access point)—A point at which the services of an OSI
layer are made available to the next higher layer. See also SAPI.
SAPI (service access point identifier)—A logical point at which data
link layer services are provided by a data link layer entity to a layer
3 entity. See also SAP.
serial port—The connector on a PC used to attach serial devices
(those that need to receive data one bit after another), such as a
mouse, a printer or a modem. This consists of a 9- or 25-pin connec-
tor that sends data in sequence (bit by bit). Serial ports are referred
to as COMx ports, where x is 1 to 4 (e.g., COM1 through COM4). A
serial port contains a conversion chip called a UART that translates
between internal parallel and external serial formats.
service—The requirements offered by an RPOA to its customers to
satisfy specific telecommunications needs.
signaling—The process of establishing, maintaining, accounting for,
and terminating a connection between two endpoints (e.g., the user
premises and the telco CO). Central office signals to the user pre-
mises can include ringing, dial tone, speech signals, etc. Signals
from the user’s telephone can include off-hook, dialing, speech to
far-end party, and on-hook signals.
In-band signaling techniques include pulse and tone dialing. With
common channel signaling, information is carried out-of-band. In
ISDN, signaling includes the call establishment, call progress
monitoring, call termination and enhanced telephone features
provided typically by the D-Channel. See also SS7, out-of-band
signaling, and in-band signaling.
SPID (service profile identifier)—In North America, the ISDN
network parameter for logical terminal identification and tracking,
provided by the ISDN provider. The voice SPID and data SPID
identify a particular set of service or feature parameters. They are
assigned by the ISDN service provider, in the form of a string of up
to 20 characters, at subscription time. The SPID actually points to a
specific location in central office memory where the relevant
informartion is stored.
SS7 (Signaling System 7)—An ITU-T and ANSI standard for digital
out-of-band signalling between central offices that provides much of
the network switching intelligence to support many ISDN functions
stop bit—One of the variables used for timing in asynchronous data
transmission. Depending on the devices, each character may be
trailed by 1, 1.5, or 2 stop bits.
subscriber loop—The pair of wires that connect the end user to the
telephone network. These wires provide ISDN service, but also
require an NT1 at the enduser location as well as the LT at the
network end. See also local loop.
supplementary services (SS)—ISDN functions beyond the basic
requirements; includes videoconferencing, fast dialing, call waiting,
call forwarding, calling line ID.
SVC (switched virtual circuit)—A type of data transmission where
the connection is maintained only until the call is cleared.
SVD (simultaneous voice and data)—A technology for letting a user
send data via a modem, and use a handset to talk to another user at
the same time over the same connection. The alternative, making a
second call, can be expensive or even impossible. The uses for SVD
are telecommuting, videoconferencing, distant learning, tech sup-
port, etc.
switched 56—A circuit-switched (full duplex digital synchronous
data transmission) service that lets you dial a number and transmit