Multi-Tech Systems MTA128ST-USB - Manual (Page 91)

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Glossary
MTA128ST-USB
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.
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.
S
S reference point—Provides the connection between NT2
equipment 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.
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 premises 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 information 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 asynch-
ronous 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
support, etc.
switched 56—A circuit-switched (full duplex digital
synchronous data transmission) service that lets you dial a
number and transmit data to it at 56 Kbps. It is a relatively
low cost service, widely used in North America for
telecommuting, videoconferencing and high speed data
transfers. Many phone companies are phasing out
switched 56 in favor of ISDN service.
switched line—In communications, a physical channel
established by dynamically connecting one or more
discreet segments. This connection lasts for the duration of
the call after which each segment may be used as part of a
different channel. Contrast with leased line.
switched network—A network in which a temporary
connection is established from one point via one or more
segments.
synchronous transmission—The transmission of data
which involves sending a group of characters in a packet.
This is a common method of transmission between
computers on a network or between modems. One or more
synchronous characters are transmitted to confirm clocking
before each packet of data is transmitted. Compare to
Asynchronous Transmission.
T
T—Provides the connection between the NT1 and NT2.
Can be internal to or external from the PABX. Provides the
connection between the NT1 equipment and the TA or TE-
1. Can provide both Primary Rate and Basic Rate services.
TA—See terminal adapter.
TCP/IP (Transmission Control Protocol / Internet
Protocol)—A multi-layer set of protocols developed by the
US Department of Defense to link dissimilar computers
across dissimilar and unreliable LANs.
TEI (terminal endpoint identifier)—A unique number that is
assigned to an ISDN terminal adapter at subscription time.
The TEI is used by the central office to identify the various
TAs connected to the ISDN network. The TEI number can
be fixed (in the range of 0-63), dynamically, or
automatically assigned at the CO each time the TA is
connected to the ISDN interface and powered up.
TE1 (Terminal Equipment Type 1)—A terminal device with
a standard ISDN interface (an ISDN-compatible terminal).
TE2 (Terminal Equipment Type 2)—A terminal device with
a non-ISDN interface, such as RS232, RS449, V.35 or
X.21. Can be a telephone, data terminal, or voice/data
worrkstation, etc.