User guide

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Glossary
Multi-Tech Systems, Inc. MultiVOIP User Guide
I/O Addresses: Locations within the I/O address space of your computer used by a device, such as an expansion card, a serial
port, or an internal modem. The address is used for communication between software and a device.
IRQ Level (Interrupt Request Level): The notification a processor receives when another portion of the computer's hardware
requires its attention. IRQs are numbered so that the device issuing the IRQ can be identified, and so IRQs can be prioritized.
ISA (Industry Standards Architecture) (pronounced "ice a"): The classic 8 or 16-bit architecture introduced with IBM's PC-AT
computer.
ITU-TSS (formerly CCITT): International Telecommunications Union-Telecommunications Sector; the United Nations organization
that prepares standards ("Recommendations") for resolving communications issues and problems.
K
Key Telephone System (KTS): Phone devices with multiple buttons that let you select incoming or outgoing CO phone lines
directly. Similar in operation to a PBX, except a KTS you don't have to dial a "9" for a call outside the building.
Key Service Unit (KSU): A small device containing the switching electronics for a business key telephone system (KTS).
Key Set: A phone set with several buttons for call holding, line pickup, intercom, autodialing, etc. Also called a touchtone phone
(Ericsson) and a KTS (Key Telephone Set).
L
LAPB: Link Access Procedure Balanced; based on the X.25 Layer 2 specification. A full-duplex point-to-point bit-synchronous
protocol commonly used as a data link control protocol to interface X.25 DTEs. LAPB is the link initialization procedure that
establishes and maintains communications between the DTE and the DCE.
LAPD: Link Access Protocol for the D-Channel; based on the ISDN Q.921 specification. A full-duplex point-to-point bit-synchronous
link-level protocol for ISDN connections; different from LAPB in its framing sequence. Transmission is in units called "frames", and
a frame can contain one or more X.25 packets.
Listed Directory Number (LDN): The main number assigned by the telco; the number listed in the phone directory and also
provided by Directory Assistance. Some devices can have more than one LDN, such as ISDN devices that have one LDN for voice
and another LDN for data.
Local Area Network (LAN): 1. A computer network located on a user's premises within a limited geographical area. Communica-
tion within a local area network is not subject to external regulations; however, communication across the LAN boundary can be
subject to some form of regulation. 2. A LAN does not use store and forward techniques. 3. A network in which a set of devices are
connected to one another for a communication and that can be connected to a larger network.
Local Access and Transport Area (LATA): A post-divestiture geographical area generally equivalent to a Standard Metropolitan
Statistical Area. At divestiture, the territory served by the Bell system was divided into approximately 161 LATAs. The Bell Operating
Companies (BOCs) provide Intra-LATA services.
Local Exchange Carrier (LEC): The local phone company which provides local (i.e., not long distance) transmission services. AKA
"telco". LECs provide T1 or FT1 access to LDCs (unless the T1 circuit is completely intra-LATA). Inter-LATA T1 circuits are made up
of a combination of Access and Long Haul facilities.
Local Loop: A transmission path, typically twisted-pair wire, between an individual subscriber and the nearest public telecommuni-
cations network switching center. The wires provide ISDN service, but require an NT1 at the user end and an LT at the network end.
(AKA, "loop" or "subscriber loop".)
Logical Link Control (LLC2): In a local area network, the protocol that governs the exchange of transmission frames between
data stations independently of how the transmission medium is shared. The LLC2 protocol was developed by the IEEE 802
committee and is common to all LAN standards.
Logical Unit (LU): A type of network accessible unit that enables end users to gain access to network resources and communicate
with each other.
M
Management Information Base (MIB): A database of network management information used by the Common Management
Information Protocol (CMIP) and the Simple Network Management Protocol (SNMP).
Modem: A communications device that enables a computer to transmit information over a phone line. It converts the computer's
digital signals into analog signals to send over a phone line and converts them back to digital signals at the receiving end. Modems
can be internal and fit into an expansion slot, or external and connect to a serial port.
Multiplexer (Mux): 1. A device that takes several input signals and combines them into a single output signal in such a manner
that each of the input signals can be recovered. 2. A device capable of interleaving the events of two or more activities or capable of
distributing the events of an interleaved sequence to the respective activities. 3. Putting multiple signals on a single channel.
Multiprotocol: A device that can interoperate with devices utilizing different network protocols.