Multi-Tech Systems Multivoip 200 Model Mvp200/800 Standalone Voice/ip Getaway User Guide

							81 Glossary
Handshaking:  A process that two modems go through at the time of call setup to establish synchronization over the data communications
link.  It is a synchronization and negotiation process accomplished by the exchange of predefined, mutually recognized control codes.
High-level Data Link Control (HDLC):   An ISO standard, bit-oriented data communications protocol that provides nearly error-free data
transfers.
I
Hexadecimal:  A base 16 numbering system used to represent binary values.  Hex uses the numbers 0-9 and the letters A-F: usually notated
by an h (e.g., 4CF h, read four charley fox, hex).  The result is that one hex digit represents a 4-bit value.
Implicit congestion management:  A method of informing the terminal that the network is busy. This method relies on the end-system
protocol to detect and fix the congestion problem.   (TCP/IP is an example of a protocol using only implicit congestion management.) See also
explicit congestion management.
In-band:  Refers to the type of signalling over the conversion path on an ISDN call.  Contrast out-of-band.
 Insufficient Ones:   A T1 error condition that is logged when less than one 1 in 16 0s or less than 12.5 % average 1s density  is received.
Inter Exchange Carrier (IEC):  The long distance company (LE) whos central office provides the point of reference for T1 access.   Any
common carrier authorized by the FCC to carry customer transmissions between LATAs.
Internet:  Refers to the computer network of many millions of university, government and private users around the world.  Each user has a
unique Internet Address.
 Internet Address (IP Address):  A unique 32-bit address for a specific TCP/IP host on a network. Normally printed in dotted decimal format
(e.g., 129.128.44.227).
Internet Protocol (IP):  A protocol used to route data from its source to its destination in an Internet environment.  The Internet Protocol was
designed to connect to local area networks.  Although there are many protocols that do this, IP refers to the global system of interconnecting
computers.  It is a highly distributed protocol (each machine only worries about sending data to the next step in the route).
Internetwork Packet Exchange (IPX):  A NetWare communications protocol used to route messages from one node to another.  IPX
packets include network addresses and can be routed from one network to another.  An IPX packet can occasionally get lost when crossing
networks, thus IPX does not guarantee delivery of a complete message.  Either the application has to provide that control, or NetWares SPX
protocol must be used.
Interoperable:  Devices from different vendors that can exchange information using a standards base protocol.
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 computers 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 IBMs PC-AT computer.
ISDN (Integrated Services Digital Network):    An International telecommunications standard for transmitting voice, video and data over a
digital communications line.  ISDN is a  world-wide telecommunications service that uses digital transmission and switching technology to
support voice and digital data communications.  Frame relay was partially based on ISDNs data link layer protocol (LAPD).  Frame relay can
be used to transmit across ISDN services offering circuit-switched connection at 64K bps and higher speeds. Contrast Public Switched
Telephone Network (PSTN).
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 dont 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 telephone 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 may
contain one or more X.25 packets. 
						

							82 MultiVOIP User Guide
Line Coding:  The representation of 1s and 0s on a T1 line.  The two methods of line coding commonly used, B8ZS and AMI, differ in the
restrictions placed on user data.  T1 line coding ensures that sufficient timing information is sent with the digital signal to ensure recovery of
all the bits at the far end.  Timing information on the T1 line is included in the form of 1s in the data stream; a long string of 0s in the data
stream could cause problems recovering the data.
Line Termination (LT):  The electronics at the ISDN network side of the user/network interface that complements the NT1 at the user side.
The LT and the NT1 together provide the high-speed digital line signals required for BRI access.
Listed Directory Number (LDN):  The main number assigned by the telco; the number listed in the telephone 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 users premises within a limited geographical area.  Communication within
a local area network is not subject to external regulations; however, communication across the LAN boundary may 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 combina-
tion of Access and Long Haul facilities.
Local Management Interface (LMI):  A specification for frame relay equipment that defines status information exchange.
Local Loop:  A transmission path, typically twisted-pair wire, between an individual subscriber and the nearest public telecommunications
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 commitee 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.
Long Haul:  The T1 element that connects to the Access portion of the long distance companys (LDCs) central office.  The LDC is com-
monly called the point of presence (POP).  Each LDC has a number of POPs, located throughout the country.  The LDC is also called an IEC
(Inter Exchange Carrier).
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).
Megacom:   An AT&T service with a normal WATS line (typically T1) between the customer premise and the AT&T serving class 4 CO  are
the customers responsibility.
MegaLink:    BellSouths leased T1 service.
Message:  Associated with such terms as packet, frame, and segment.  1. In information theory, an ordered series of characters intended to
convey information.  2. An assembly of characters and sometimes control codes that is transferred as an entry from an originator to one or
more recipients.
Modem:  A communications device that enables a computer to transmit information over a telephone line.  It converts the computers digital
signals into analog signals to send over a telephone 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.
Multithreading:  The ability of a software system to be able to handle more than one transaction concurrently.  This is contrasted to the case
where a single transaction is accepted and completely processed before the next transaction processing is started.
N
Nailed Connection:  A permanent or dedicated circuit of a previously switched circuit or circuits.
Nailed-up Circuit:  A semipermanent circuit established through a circuit-switching facility for point-to-point connectivity. 
						

							83 Glossary
NAK (Negative Acknowledgment):  Communications code used to indicate that a message was not properly received, or that a terminal
does not wish to transmit.  Contrast with ACK.
Network:  A group of computers connected by cables or other means and using software that enables them to share equipment, such as
printers and disk drives to exchange information.
Node:  Any point within a network which has been assigned an address.
O
Object-Orientated:  A method for structuring programs as hierarchically organized classes describing the data and operations of objects that
may interact with other objects.
Office Channel  Unit - Data Port (OCU-DP):   The CO channel bank used as the interface between the customers DSU and the channel
bank.
Off-hook:  The condition of a device which 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.   Contrast on-hook.
Off Premise Extension (OPX):  An extension or phone that terminates in a location other than that of the PBX.   Commonly used to provide
a corporate member with an extension of the PBX at home.
Ones Density:  the measure of the number of logical 1s on a T1 line compared to a given total number of bits on that line; used for timing
information in data recovery in AMI and B8ZS.
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.  Contrast off-hook.
Open Shortest Path First (OSPF):  A hierarchical Interior Gateway Protocol (IGP) routing algorithm for IP that is a proposed standard for
Internet.  OSPF incorporates least-cost routing, equal-cost routing, and load balancing.
Outage:   The measure of the time during which a circuit  is not available for use due to service interrupt.  Outage is the complement of circuit
availability (100% minus  % available = % outage).
Out-of-band:  Signaling that is separated from the channel carrying the information (i.e., the voice/data/video signal is separate from the
carrier signal).  Dialing and various other supervisory signals are included in the signaling element.  Contrast In-band signaling.
Out of Frame (OOF):  A T1 alarm condition that is logged on the loss of 2, 3 or 4 of 5 consecutive FT framing bits.
P
Packet:  1. In data communication, a sequence of binary digits, including data and control signals, that is transmitted and switched as a
composite whole.  The data, control signals and, possibly, error control information are arranged in a specific format.  2. Synonymous with
data frame.  3. In TCP/IP, the unit of data passed across the interface between the Internet layer and the link layer.  A packet includes an IP
header and data.  A packet can be a complete IP datagram or a fragment of an IP diagram.  4. In X.25, a data transmission information unit.
A group of data and control characters, transferred as a unit, determined by the process of transmission.  Commonly used data field lengths
in packets are 128 or 256 bytes.  5. The field structure and format defined in the CCITT X.25 recommendation.
Packet Assembler/Dissembler (PAD):  Used by devices to communicate over X.25 networks by building or stripping X.25 information on or
from a packet.
Packet Data:  The information format (packetized) used for packet-mode calls.
Packet Mode:  Refers to the switching of chunks of information for different users using statistical multiplexing to send them over the same
transmission facility.
Parity bit:  An extra bit attached to each byte of synchronous data used to detect errors in transmission.
Permanent Virtual Circuit (PVC):  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.
Physical Unit (PU):  The component that manages and monitors the resources (such as attached links and adjacent link stations) associated
with a node, as requested by an SSCP via an SSCP-PU session.  An SSCP activates a session with the physical unit in order to indirectly
manage, through the PU, resources of the node such as attached links.  This term applies to type 2.0, type 4, and type 5 nodes only.
Point of Presence (POP):  The central offices end points of the long distance carriers.
Point to Point Protocol (PPP):   A protocol that lets a PC user access TCP/IP (Internet member) using an ISDN terminal adapter or a high-
speed modem over a standard telephone line.
Port:  A location for input or output data exchange.  Computers, muxes, etc. have ports for various purposes.
Primary Rate Interface (PRI):  Used on ISDN.  In North America, and Japan, PRI is one 64Kbps D channel and 23 B channels.  Elsewhere,
it is one D channel and 30 B channels. 
						

							84 MultiVOIP User Guide
Primitive:  An abstract representation of interaction across 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.
Private Branch Exchange (PBX):  A telephone exchange located on the customers premises.  The PBX provides a circuit switching facility
for telephone extension lines within the building, and access to the public telephone network. See also Exchange.
PROM (Programmable Read Only Memory - pronounced prom):    A permanent memory chip that can be programmed or filled by the
customer after by the manufacturer has set initial values.  Contrast with ROM.
Protocol:  1. A set of semantic and syntactic rules that determines the behavior of functional units in achieving communication.  2. In Open
Systems Interconnection architecture, a set of semantic and syntactic rules that determine the behavior of entities in the same layer in
performing communication functions.  3. In SNA, the meanings of and the sequencing rules for requests and responses used for managing
the network, transferring data, and synchronizing the states of network components.  4. Synonymous with line control discipline.
PSTN (Public Switched Telephone Network):  A worldwide public voice telephone network that is used as a telecommunications medium
for the transmission of voice, data and other information.
Public Data Network (PDN):  A packet-switched network that is available to the public for individual (subscriber) use.  Typically, controlled
by a government or a national monopoly.
Public Switched  Telephone Network (PSTN):  The group of circuit-switching voice carriers, which are commonly used as analog data
communications services.
Pulse Code Modulation (PCM):  1. In data communication, variation of a digital signal to represent information; for example, by means of
pulse amplitude modulation (PAM), pulse duration modulation (PDM), or pulse position modulation (PPM).  2. Transmissions of analog
information in digital form through sampling and encoding the samples with a fixed number of bits.
Pulse dialing:  One of two methods of dialing a telephone, usually associated with rotary-dial phones.  Compare with tone dialing.
Q
Quantizing:  The process of analog-to- digital conversion by assigning a range, from the contiguous analog values, to a discrete number.
R
Random Access Memory  (RAM):    A computers 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.
Rate Enforcement:  The concept in frame relay where frames sent faster than the CIR are to be carried only if the bandwidth is available,
otherwise they are to be discarded.  (The frame relay network assumes that anything exceeding the CIR is of low priority.)  Rate enforcement
makes sure that the network will not get so congested that it isnt able to meet the agreed on CIR
Recognized Private Operating Agency            (RPOA):  A corporation, private or government-controlled, that provides telecommunications
services. RPOAs, such as AT&T, participate as non-voting members in the CCITT.
Red Alarm:  A T1 error condition generated when a local failure (e.g., loss of synchronization) iexists for 2.5 seconds, causing a Carrier
Group Alarm (CGA).  See also Blue Alarm and Yellow Alarm.
Request for Comment (RFC):  A set of papers in which Internet standards (published and proposed),  along with generally-accepted ideas,
proposals, research results, etc. are published.
Ring Down Box:  A device that emulates a CO by generating POTS calls for testing and product demos.
Ring Down Circuit:  A tie line connecting phones where picking up one phone automatically rings another phone.  A feature used for
emergencies to alert the person at the other phone of the incoming call.
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.
Robbed Bit Signaling: The popular T1 signaling mechanism where the A and B bits are sent by each side of the T1 termination and are
buried in the voice data of each voice channel in the T1 circuit.  Since the bits are robbed infrequently, voice quality is remains relatively
uncompromised. See bit robbing.
The robbed-bit signaling technique is used in D4 channel banks to convey signaling information.  The eighth (least significant) bit of each of
the 24 8-bit time slots is robbed  every sixth frame  to convey voice-related signaling information such as on-hook, off-hook, etc., for each
channel.
Router:  A device that connects two networks using the same networking protocol.  It operates at the Network Layer (Layer 3) of the OSI
model for forwarding decisions.
Routing Information Protocol (RIP):  A distance vector-based protocol that provides a measure of distance, or hops, from a transmitting
workstation to a receiving workstation. 
						

							85 Glossary
RS232-C:  An EIA 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.
RS-422:   The EIA standard for a balanced interface with no accompanying physical connector.  RS-422 products can use screw terminals,
DB-9, various DB-25, and DB-37 connectors.
RS-530:  The EIA standard for the mechanical/electrical interface between DCEs and DTEs transmitting synchronous or asynchronous serial
binary data. RS-530 provides for high data rates with the same connector used for RS-232; however, it is incompatible with RS-232.
S
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 (i.e., COM1 through COM4).  A serial port contains a conversion chip called a UART which translates between
internal parallel and external serial formats.
Service:  The requirements offered by an RPOA to its customers to satisfy specific telecommunications needs.
Severely Errored Seconds (SES):  Refers to a typical T1 error event where an error burst occurs (a short term,  high bit-error rate that is
self-clearing).  Per the ITU-T (CCITT) G.821: any second in which the BER is less than 1x10
-3.
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
users 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.
Simple Network Management Protocol (SNMP):  TCP/IP protocol that allows network management.
Simultaneous Voice Data (SVD):  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.
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.
Superframe (D4):  A T1  transmission format that consists of 12 DS1 frames, or 2316 bits.  A DS1 frame consists of 193 bit positions. A
frame overhead bit is  in the first position, and it is used for frame and signaling phase alignment only.
Subscriber Loop:  See Local loop.
Switched 56:  A circuit-switched (full duplex digital synchronous data transmission) service that lets you dial a number and transmit data to it
at 56K bps.  It is a relatively low cost service, widely used in North America for telecommuting, videoconferencing and high speed data
transfers.  Many phone companies are (or will be) phasing out Switched 56 in favor of ISDN service.
Switched Virtual Circuit  (SVC):  A type of data transmission where the connection is maintained only until the call is cleared.
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 Data Link Control (SDLC):  A discipline conforming to subsets of the Advanced Data Communications Control Procedures
(ADCCP) of the American National Standards Institute (ANSI) and High-level Data Link Control (HDLC) of the International Organization for
Standardization, for managing synchronous, code-transparent, serial-by-bit information transfer over a link connection.  Transmission
exchanges may be duplex, or half-duplex over switched or nonswitched links.  The configuration of the link connection may be point-to-point,
multipoint, or loop.
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.
Systems Network Architecture (SNA):  The description of the logical structure, formats, protocols, and operational sequences for transmit-
ting information units through, and controlling the configuration and operation of of, networks.
T
Tariff:  The rate/availability schedule for telephone and ISDN services from a regulated service provider.
TCP/IP:  A set of communication protocols that support peer-to-peer connectivity functions for both local and wide area networks.
T Carrier:  The generic name for a digitally multiplexed carrier system.  In the North American digital hierarchy, a T is used to designate a DS
(digital signal) level hierarchy. Examples: T1 (DS1) is a 1.544 M bps 24-channel designation.   In Europe, T1 is called E1.   The T Carrier
system was originally designed for transmitting digitized voice signals, but has since been adapted for digital data applications. 
						

							86 MultiVOIP User Guide
T1:  A digital transmission link capable of 1.544M bps.  T1 uses two pairs of normal UTP, and can handle 24 voice conversations, each
digitized at 64K bps.  T1 is a standard for digital transmission in the U.S., Canada, Japan and Hong Kong.  T1 is the access method for high-
speed services such as ATM, frame relay, and SMDS.  See also T Carrier, T1 line and FT1.
T1 Channel Tests:  A set of diagnostics that vary by carrier, used to verify a T1 channel operation.  Can include Tone, Noise Level, Impulse
Noise Level, Echo Cancellors, Gain, and Crosstalk testing.
T1 Framing:   To digitize and encode analog voice signals requires 8000 samples per second (twice the highest voice frequency of 4000
Hz).  Encoding in an 8-bit word provides the basic T1 block of 64K bps for voice transmission.  This Level 0 Signal, as its called, is repre-
sented by DS-0, or Digital Signal at Level 0.    24 of these voice channels are combined into a serial bit stream (using TDM), on a frame-by-
frame basis.  A frame is a sample of all 24 channels; so adding in a framing bit gives a block of 193 bits (24x8+1=193).  Frames are transmit-
ted at 8000 per second (the required sample rate), creating a 1.544M (8000x193=1.544M)  transmission rate.
T1 Line:   A digital communications facility that functions as a 24-channel pathway for data or voice.  A T1 line is composed of two separate
elements: the Access element and the Long Haul element.
T1 Mux:   A device used to carry many sources of data on a T1 line.  The T1 mux assigns each data source to distinct DS0 time slots within
the T1 signal.  Wide bandwidth signals take more than one time slot.  Normal voice traffic or 56/64K bps data channels take one time slot.
The T1 mux may use an internal or external T1 DSU; a channel bank device typically uses an external T1 CSU.
Transmission Control Protocol / Internet Program (TCP/IP):  A multilayer set of protocols developed by the US Department of Defense to
link dissimilar computers across dissimilar and unreliable LANs.
Terminal: The screen and keyboard device used in a mainframe environment for interactive data entry.  Terminals have no box, which is to
say they have no file storage or processing capabilities.
Terminal  Adapter (TA):  An ISDN DTE device for connecting a non-ISDN terminal device to the ISDN network.  Similar to a protocol
converter or an interface converter, a TA connects a non-ISDN device between the R and S interfaces.  Typically a PC card.
Tie line:   A dedicated circuit linking two points without having to dial a phone number (i.e., the line may be accessed by lifting the telephone
handset or by pushing a button).
Time-Division Multiplexing (TDM):  Division of a transmission facility into two or more channels by allotting the common channel to several
different information channels, one at a time.
Time Slot:  One of 24 channels within a T1 line.  Each channel has a 64K bps maximum bandwidth.  Time slot  implies the time division
multiplexing organization of the T1 signal.
Toll Call:   A call to a location outside of your local service area (i.e., a long distance call).
Tone dialing:  One of two methods of dialing a telephone, usually associated with Touch-Tone® (push button) phones.  Compare with pulse
dialing.
Topology:  Physical layout of network components (cables, stations, gateways, and hubs).  Three basic interconnection topologies are star,
ring, and bus networks.
Transmission Control Protocol (TCP):  A communications protocol used in Internet and in any network that follows the US Department of
Defense standards for internetwork protocol.  TCP provides a reliable host-to-host protocol between hosts in packet-switched communications
networks and in interconnected systems of such networks.  It assumes that the Internet protocol is the underlying protocol.
Transport Layer:  Layer 4 of the Open Systems Interconnection (OSI) model; provides reliable, end-to-end delivery of data, and detects
transmission sequential errors.
Transport Protocol Data Unit (TPDU):  A transport header, which is added to every message, contains destination and source addressing
information that allows the end-to-end routing of messages in multi-layer NAC networks of high complexity.  They are automatically added to
messages as they enter the network and can be stripped off before being passed to the host or another device that does not support TPDUs.
Trunk:  Transmission links that interconnect switching offices.
TSR (terminate and stay resident):  A software program that remains active and in memory after its user interface is closed. Similar to a
daemon in UNIX environments.
Tunneling:  Encapsulation data in an IP packet for transport across the internet.
Twisted pair wiring:  A type of cabling with one or more pairs of insulated wires wrapped around each other.  An inexpensive wiring method
used for LAN and telephone applications, also called UTP wiring.
U
UART (Universal Asynchronous Receiver/Transmitter) (pronounced you art):  A chip that transmits and receives data on the serial
port.  It converts bytes into serial bits for transmission, and vice versa, and generates and strips the start and stop bits appended to each
character.
UNIX:  An operating system developed by Bell Laboratories that features multiprogramming in a multi-user environment.
Unshielded Twisted Pair (UTP):  Telephone-type wiring.  Transmission media for 10Base-T. 
						

							87 Glossary
V
V.25bis:  An ITU-T standard for synchronous communications between a mainframe or host and a modem using HDLC or other character-
oriented protocol.
V.54:  The ITU-T standard for local and remote loopback tests in modems, DCEs and DTEs.  The four basic tests are:
  local digital loopback (tests DTE send and receive circuits),
  local analog loopback (tests local modem operation),
  remote analog loopback (tests comm link to the remote modem), and
  remote digital loopback (tests remote modem operation).
Virtual Circuit:  A logical connection.  Used in packet switching wherein a logical connection is established between two devices at the start
of transmission. All information packets follow the same route and arrive in sequence (but do not necessarily carry a complete address). 
						

							88 MultiVOIP User Guide
Index
A
Archie .................................................................... 71
B
Back Panel ............................................................ 12
C
Collision ................................................................. 11
Command Connector ............................................ 12
Configuration Port Setup ....................................... 40
Configuration Utilities ............................................ 40
Connectors
Command .......................................................... 12
Power ................................................................ 12
D
DNS ....................................................................... 71
Download Firmware .............................................. 40
F
Finger .................................................................... 71
Front Panel
Description ......................................................... 11
FTP ....................................................................... 71
FTP Site ................................................................ 67
G
Gopher .................................................................. 71
H
HTML .................................................................... 71
HTTP ..................................................................... 71
I
Internet
FTP Site ............................................................. 67
Internet Protocol (IP) ............................................. 72
IP ........................................................................... 72
L
LEDs
56K DSU
RD .................................................................. 11
Ethernet ............................................................. 11
CL .................................................................. 11
LNK ................................................................ 11
RD .................................................................. 11
TD .................................................................. 11
Power ................................................................ 11Limited Warranty ................................................... 64
O
On-line Warranty Registration ............................... 64
P
Ping ....................................................................... 71
POP ....................................................................... 71
Power
Connector .......................................................... 12
Proxy Server Configuration ............................ 41, 62
ProxyServer Software ........................................... 40
R
Receive Data ......................................................... 11
Remote Configuration
LAN-Based Procedure ....................................... 58
Remote Management ............................................ 60
Telnet ................................................................. 60
WEB Management ............................................. 62
S
Service .................................................................. 65
SMTP .................................................................... 71
SNMP .................................................................... 71
Software ................................................................ 40
Description ......................................................... 40
Specifications
Command Port .................................................. 13
Electrical/Physical .............................................. 13
Ethernet Port ..................................................... 13
T
TCP/IP ............................................................ 60, 70
Tech Support ......................................................... 65
Telnet .............................................................. 60, 71
Proxy Server Configuration ............................... 62
The Multi-Tech BBS .............................................. 66
Traceroute ............................................................. 71
Transmit Data ........................................................ 11
U
Uninstall Proxy Server Configuration .................... 40
W
Warranty ................................................................ 64
On-line Registration ........................................... 64
WEB Server .......................................................... 62