Multi Tech Equipment MTA128ST - Manual (Page 58)

Glossary
MTA128ST/NT 58
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.
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 connector 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 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 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, or2
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 0f 0- 63, or dynamic, automatically
assigned at the CO each time the TA is connected to the
ISDN interface and powered up.
TE1 (Terminal Equipment Type 1)—Aterminal device with
a standard ISDN interface (an ISDN-compatible
terminal).
TE2
(Terminal Equipment Type 2)—A terminal device with a
nonISDN interface, such as RS232, RS449, V.35 or X.21.
Can be a telephone, data terminal, or voice/data
worrkstation, etc.
telecommunication service —A function, such as bearer
service and teleservice, offered by an RPOA to its customer
in order to satisfy a specific telecommunications
requirement. See also ISDN, RPOA, and bearer service.