Business Internet Access Dictionary - T1 Internet Connection glossary of terms
The following provides a glossary of terms and definitions that are commonly used when discussing Business Internet Access and T1 Internet Connections. We hope this will provide a good reference for you during your introduction to T1 Services. Please feel free to Contact Us if you think that important terms or definitions related to T1 and high speed internet are missing from this page or you need clarification on any.
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B C
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H I
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K L
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W X
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A
Adapter:
A device that enables something to be used in a different way from which is was intended, or makes
different pieces of equipment compatible.
Analog:
An information form that is represented by a continuous and smoothly varying amplitude or frequency
changes over a certain range such as voice or music.
Analog Telephone Adapter (ATA):
A device that converts the analog signals from a conventional phone into a format acceptable for
transmission over an internet connection, and vice versa at the receiving end. This device is commonly
used for VoIP Phone Services.
Area Code:
A three digit number that generally identifies a geographic area of a switch that provides service
to a telephone device (for America and Canada).
Asymmetric Digital Subscriber Line (ADSL):
Most homes and small business users are connected to an asymmetric DSL
(ADSL) line. Refer to DSL definition below for more info on DSL. ADSL
divides up the available frequencies in a line on the assumption that
most Internet users look at, or download, much more information than
they send, or upload. Under this assumption, if the connection speed
from the Internet to the user is three to four times faster than the
connection from the user back to the Internet, then the user will see
the most benefit (most of the time).
Asynchronous Transfer Mode (ATM):
The international standard for cell relay in which multiple service types (such as voice, video, or data)
are conveyed in fixed-length (53-byte) cells. Fixed-length cells allow cell processing to occur in hardware,
thereby reducing transit delays.
B
Bits per second (bps) or Bandwidth:
The most common measurement for data transmission. It indicates the number of bits that can be
transferred to or from a communications device in one second.
Broadband:
The use of cable to provide data transfer using analog (radio-frequency) signals. Digital signals
must be passed through a modem and transmitted over one of the frequency bands of the cable.
Multiple channels carry data on a single physical cable. Cable TV is an example of broadband
transmission. The term is commonly associated with
high speed data transfer connections.
C
Capacity:
The maximum information carrying ability of a communications facility or system.
Cat5 Wiring:
Category 5 unshielded twisted-pair wiring commonly used for 10BaseT and 100BaseT Ethernet networks.
Cat6 Wiring:
Category 6 unshielded twisted-pair wiring commonly used for 1000BaseT (Gigabit) Ethernet networks.
Central Office (CO):
The local telephone company office to which all local loops in a given area connect and in which circuit
switching of subscriber lines occurs.
Channel Bank:
A channel bank is simply a small device that takes in a T1 line an splits it into separate streams or channels depending on whether that
channel or stream is carrying voice or data.
Circuit switching:
A process of connecting two points in a communications network where the path (switching points) through the
network remains fixed during the operation of a communications circuit. While a circuit switched connection is
in operation, the capacity of the circuit remains constant regardless of the amount of content (e.g. voice or
data signal) that is transferred during the circuit connection.
Class 5 switch:
Telephone company switch.
Codec (coder/decoder):
A technique used to compress/decompress speech or audio signals.
Competitive Local Exchange Carrier (CLEC):
A company that builds and operates communication networks in metropolitan areas and provides its customers
with an alternative to the local telephone company.
Customer Premises Equipment (CPE):
Terminating equipment (such as terminals, telephones, and modems) supplied by the telephone company, installed at
customer sites and connected to the telephone company network. Can also refer to any telephone equipment residing on
a customer site.
D
Data:
1) A general term for information.
2) A collection of interrelated, unique data items or records, in one or more computer files.
Data Communications:
The transmission and reception of data between locations. Data communications require a combination of hardware (terminals,
modems, multiplexers, and other hardware) and software.
Data T1:
A T1 line dedicated to carrying data only.
Delay:
This is always measured in seconds or fractions of seconds. There are
delays through every electronic device even if it's only nano seconds.
1ns is 0.000000001 seconds. In a system like the internet delays are
caused by the electronics(this is usually negligible), queuing delays,
transmission distances and software delays.
Digital:
Data characters coded in discrete, separate pulses or signal levels.
Digital Signal 0 (DS0):
One timeslot or channel within a T1 frame and for voice it is usually one call. It has an effective rate of 64Kbps (8KHz sampling by 8 bits).
Digital Signal 3 (DS3):
A wide area synchronous digital transmission scheme used predominantly in North America and Japan that carries data at a rate of
44.736Mbps.
Digital Subscriber Line (DSL):
A high-speed digital switched service using existing copper pairs to connect subscriber CPE (Customer Premises Equipment) to
the Central Office. DSL handles more data downstream (data flowing towards the subscriber) than upstream (towards the network).
Duplex:
Duplex communication is the transmission of voice and/or data signals that allows simultaneous 2-way communication.
E
E1 Link:
A wide area digital transmission scheme used predominantly in Europe that carries data at a rate of 2.048Mbps.
Ethernet:
Ethernet is a packet based transmission protocol that is primarily used in LANs.
F
Fax:
A process of converting optical images into electrical signals for transmission over communication systems (phone line,
internet etc). When the electrical signal is received, it is converted back to an optical format for display or printing
of the original image. This process is commonly called FAXing.
Fax Machine:
A device that allows the user to fax information over a communication line.
Full Duplex:
Phone calls are full duplex, meaning both parties can speak at the same time. Not all voice cards can support full-duplex
operation so if you are using your PC to talk rather than a telephone with an ATA, you may have a half-duplex voice card.
G
Gateway:
A device that acts as an interface between two or more networks to connect dissimilar communications systems. A gateway
translates from one set of protocols to another, at levels from the Physical layer (Level 1) up through the Application
layer (Level 7) of the OSI Reference model.
H
H.323:
A standard approved by the International Telecommunication Union (ITU) in 1996 to promote compatibility in videoconference
transmissions over IP networks.
Half Duplex:
Phone calls are half duplex, meaning only one party can talk and one party listen at the same time.
High-Level Data Link Control (HDLC):
Layer 2 protocol used to transfer data in either a point to point or in a point to multipoint network.
Hertz:
A measurement unit for frequency that is equal to the number of cycles per second of a waveform.
Hosted VoIP or Hosted IP-PBX:
This type of VoIP solution is best suited to either small companies that require multiple lines or geographically
separated offices of the same company that need a central point for all their communication needs. Hosted VoIP means that a VoIP provider will host your VoIP service in one location and maintain your system, alleviating you from the day to day tasks of running a
telecoms network. Regardless of the physical location of your offices they are only an extension call away.
Hypertext Transfer Protocol (HTTP):
A protocol that is used to transmit hypertext documents through the Internet. It controls and manages communications
between a Web browser and a Web server.
Hub:
A hub is a communication device that distributes communication to several devices in a network through the re-broadcasting
of data that it has received from one (or more) of the devices connected to it.
I
IEEE 802.16:
Commonly referred to as WiMAX or less commonly as WirelessMAN™ or the Air Interface Standard, IEEE 802.16 is a specification for fixed broadband wireless metropolitan access networks (MANs)
that use a point-to-multipoint architecture. Published on April 8, 2002, the standard defines the use of bandwidth between the licensed 10GHz and 66GHz and between the 2GHZ and 11GHz
(licensed and unlicensed) frequency ranges and defines a MAC layer that supports multiple physical layer specifications customized for the frequency band of use and their associated regulations.
802.16 supports very high bit rates in both uploading to and downloading from a base station up to a distance of 30 miles to handle such services as VoIP, IP connectivity and TDM voice and data.
Incumbent Local Exchange Carrier (ILEC):
Traditional telephone company. In the U.S., the Regional Bell Operation Companies (RBOCs) that were formed after the
divestiture of AT&T and the Independent Operating Companies (IOCs) that usually are located in more rural areas or single
cities are called ILECs.
Internet:
The current-day public and global computer network or "information super-highway." The Internet is an outgrowth and combination
of a variety of university and government sponsored computer networks. Today, the Internet is made up of millions upon millions
of computers and sub-networks, almost entirely supported by commercial funds except in countries where deregulation has not
occurred. The internet is the substrate and chief communications backbone for the World Wide Web (WWW), the "graphical
interface" of the Internet.
Internet Protocol (IP):
Method or protocol by which data is sent from one computer to another on the Internet. Each computer (known as a host) on the
Internet has at least one IP address that uniquely identifies it from all other computers on the Internet.
IP Telephony (Internet Protocol telephony):
General term for the technologies that use the Internet Protocol's packet-switched connections to exchange voice, fax, and other
forms of information that have traditionally been carried over the dedicated circuit-switched connections of the public switched
telephone network (PSTN). Also commonly referred to as IP Phone Service, VoIP Phone Service, and Broadband Phone Service.
ISP (Internet Service Provider):
A business that provides subscriber-based access to the Internet. ISPs use Internet Routers, Servers and Rack-Mounted
modems to provide a variety of services including Web Site hosting, FTP service, e-mail accounts, unified messaging, audio
and video broadcasting and in some cases, Internet Telephony (VoIP) and Fax Gateway service.
J
Jack:
A socket connector designed for the insertion of a plug, commonly used for audio devices (e.g. used for connecting your
headphones to your audio equipment).
Jitter:
Jitter when applied to VoIP is a variation in packet transit delay. The
causes of jitter are typically queuing, contention and serialization effects on the path through the network.
Faster, higher bandwidth networks tend to have less jitter whereas
slower networks tend to have more congestion and more jitter. A QoS
device like an ATA can help eliminate some of this jitter.
K
Kilo-bits per second (Kbps):
A measure of the number of one thousand bits transferred over a 1 second period.
Kilo-Hertz (KHz):
A measurement unit of the number of one thousand cycles per second of a waveform.
L
Local Area Network (LAN):
A group of computers and associated devices that share a common communications line or wireless link and typically share
the resources of a single processor or server within a small geographic area (for example, within an office building).
Latency:
An expression of how much time it takes for a packet of data to get from one designated point to another.
M
Managed Services:
This is when all aspects of your network i.e. routers, firewalls, upgrades,
maintenance, etc are outsourced or managed by a 3rd party.
Media Gateway Control Protocol (MGCP):
An Internet Engineering Task Force (IETF) draft standard for controlling voice gateways through IP networks.
Mega-bits per second (Mbps):
A measure of the number of one million bits to be transferred over a 1 second period.
Mega-Hertz (MHz):
A measurement unit of the number of one million cycles per second of a waveform.
Modem:
A modem converts the serial digital (binary) data from a transmitting terminal into a form suitable for retransmission
over an analog telephone channel. A second modem reconverts this signal to binary data for acceptance by the receiving
terminal.
Multiprotocol Label Switching (MPLS):
This is a technique used to reduce latency and provide Quality of Service (QoS) in IP networks. A path is set up
across the network in which all packets used in that data transfer are identified by a label in the header field,
these packets traverse the network in a predefined route. This means that each node in the network does not have to decode the whole packet to see where it should go thus reducing
the latency and increasing the Quality of Service.
N
Network:
A system of computers linked together by communication channels allowing the flow of data between the linked computers.
Network Interface Card (NIC):
An adapter circuit board installed in a computer to provide a physical connection to a network.
O
On-line:
A reference to a user being actively connected to the internet.
Optical Carrier X (OCx)
As its name suggests this is an optical medium where digital signals are modulated on top of light waves and transported over fibre rather than copper cables. There is less distortion in the signals being sent and hence this type of medium is well suited to high bandwidth links. There are 8 bandwidths associated with Optical Carrier levels as shown in the table below.
| Optical Carrier Level | Bandwidth |
| OC-1 | 51.84 Mbps |
| OC-3 | 155.52 Mbps |
| OC-12 | 622.08 Mbps |
| OC-24 | 1.244 Gbps |
| OC-48 | 2.488 Gbps |
| OC-192 | 10 Gbps |
| OC-256 | 13.271 Gbps |
| OC-768 | 40 Gbps |
OSI Reference Model:
A reference model to standardize communication systems. The model standardized nomenclature across existing protocols and
provided guidelines for new protocols using 7 layers.
P
Packet:
The unit of data that is routed between an origin and a destination on the Internet or any other packet-switched network.
Packet loss:
Occasionally in complex systems like the internet packets get lost. The
packets sometimes take so long to reach the destination that they are no
longer useful, sometime packets get corrupted and the data in them is no
longer reliable. .
Packet Switching:
A means of economically sending and receiving data over alternate, multiple network channels. The premise for packet switching
is the packet, a small bundle of information containing the payload and routing information. Packet switching takes data, breaks
it down into packets, transmits the packets and does the reverse on the other end. Packets can be sent in order and then be
received in a different order - only to be put back in the correct order in fractions of a second.
PBX:
An automated telephone switching system serving one company, located on the company's premises, and connecting to the public
telephone network.
Phone Adaptor:
See ATA. This is a device that is commonly used with VoIP Phone Service.
Point-to-Point Protocol (PPP):
Point-to-point protocol (PPP) is a connection oriented protocol that is established between two communication devices that
encapsulates data packets (such as Internet packets) for transfer between two communication points. PPP allows end users
(end points) to setup a logical connection and transfer data between communication points regardless of the underlying
physical connection (such as Ethernet, ATM, or ISDN).
Primary Rate Interface T1 (PRI T1):
A T1 line that is capable of transferring both voice and data.
Private Lines:
This is often referred to as a Point to Point line. The private line is basically an intra-office or intra-company communication path that does not use the public network i.e. the internet. These private lines can be T1, T3, E1, E3, DS3, Ethernet, OC-1, OC-3, OC-12, OC-24, OC-48, OC-192, OC-256, OC-768, etc.
Protocol:
1) A strictly defined procedure and message format allowing two or more systems to communicate over a transmission
medium.
2) A formalized set of rules that computers use to communicate. Because of the complexity of communications between systems and
the need for different communications requirements, protocols have been divided into modular layers, in which each layer
performs a specific function for the layer above.
Public Switched Telephone Network (PSTN):
The world's collection of interconnected voice-oriented public telephone networks, both commercial and government-owned.
Also referred to as the Plain Old Telephone Service (POTS).
Q
Quality of Service (QoS):
The idea that transmission rates, error rates, and other characteristics can be measured, improved, and, to some extent,
guaranteed in advance.
R
Rate-Adaptive DSL (RADSL):
This is a variation of ADSL, but the modem can adjust the speed of the connection depending on the length and quality of the line.
Real-time Transport Protocol (RTP):
RTP is a packet based communication protocol that adds timing and sequence information to each packet to allow the reassembly
of packets to reproduce real time audio and video information. RTP is a transport used in IP audio and video environments.
RJ-11 connection:
A modular connector that has 2 to 6 conductors that is commonly used to interconnect end-user telephone equipment.
RJ-45 connection:
A standard 8 wire modular connector. RJ-45 connectors are commonly used in telephone and data communication systems.
Router:
A device that connects multiple networks together and forwards packets (of data) between them.
S
Session Initiation Protocol (SIP):
A standard protocol for initiating an interactive user session that involves multimedia elements such as video, voice,
chat, gaming, and virtual reality.
Service Level Agreement (SLA):
This is part of a contract between a business and a network provider. This agreement defines what is expected from your
fractional T1, T1, Fractional DS3, DS3, OC3, etc; pipe in terms or reliability and bandwidth.
Softphone (Software Telephone):
A software program that runs on your PC (desktop or laptop) that allows you to make and receive calls over the Internet (VoIP).
You can use a headset, or a microphone and speakers, in place of a telephone. A softphone's interface typically looks like a
traditional phone dial pad. A softphone typically provides all the features and benefits associated with VoIP Solutions.
Switch:
A device that connects two separate paths together.
Symmetric DSL (SDSL):
Refer to the DSL definition for more information on DSL. This connection, used mainly by small businesses,
doesn't allow you to use the phone at the same time, but the speed of receiving and sending data is the same.
T
T1:
A wide area synchronous digital transmission scheme used predominantly in North America and Japan that carries data at a rate of 1.544Mbps.
T3:
A T3 line is equivalent to 28 T1 lines (see above) at a speed of 44.736Mbps, and is often referred to as DS3.
Time Division Multiplex (TDM):
Time Division Multiplex is where time is split between multiple cahannels. Each channel gets the same amount of time to tranmit and receive either Voice or Data. These channels are sent at regular intervals.
Transmission Control Protocol (TCP):
A session layer protocol that coordinates the transmission, reception, and retransmission of packets in a data network to
ensure reliable (confirmed) communication. The TCP protocol coordinates the division of data information into packets, adds
sequence and flow control information to the packets, and coordinates the confirmation and retransmission of packets that are
lost during a communication session. TCP utilizes Internet Protocol (IP) as the network layer protocol.
Telephone:
A device that converts your speech into an analog signal suitable for transmission over a phone line.
U
User Datagram Protocol (UDP):
UDP is a high-level communication protocol that coordinates the one-way transmission of data in a packet data network. The UDP
protocol coordinates the division of files or blocks of data information into packets and adds sequence information to the
packets that are transmitted during a communication session using Internet Protocol (IP) addressing. This allows the receiving
end to receive and re-sequence the packets to recreate the original data file or block of data that was transmitted. UDP adds
a small amount of overhead (control data) to each packet relative to other high-level protocols such as TCP. However, UDP does
not provide any guarantees to data delivery through the network.
V
Very High Bit Rate DSL (VDSL):
Refer to DSL definition for more information on DSL. VDSL is a fast connection, but works only over a short distance.
Voice T1:
A T1 line dedicated to carrying voice only.
Voicemail:
Similar to an answering machine used for conventional phones, except that the messages are saved and serviced at a central
location, rather than at the individual telephone.
Voice over IP (VoIP):
Term used in IP telephony for a set of facilities for managing the delivery of voice information using the Internet
Protocol (IP).
W
Wide Area Network (WAN):
A communications network serving geographically separate areas. A WAN can be established by linking together two or more
metropolitan area networks, which enables data terminals in one city to access data resources in another city or country.
WiMax:
Commonly referred to as WiMAX or less commonly as WirelessMAN™ or the Air Interface Standard, IEEE 802.16 is a specification for fixed broadband wireless metropolitan access networks (MANs)
that use a point-to-multipoint architecture. Published on April 8, 2002, the standard defines the use of bandwidth between the licensed 10GHz and 66GHz and between the 2GHZ and 11GHz
(licensed and unlicensed) frequency ranges and defines a MAC layer that supports multiple physical layer specifications customized for the frequency band of use and their associated regulations.
802.16 supports very high bit rates in both uploading to and downloading from a base station up to a distance of 30 miles to handle such services as VoIP, IP connectivity and TDM voice and data.
Wireless:
References the transmission of information (data, voice etc) over electromagnetic waves rather than over a wire connection.
World Wide Web (WWW):
A service that resides on computers that are connected to the Internet and allows end users to access data that is stored
on the computers using standard interface software (browsers). The WWW (commonly called the "web") is associated with
customers that use web browsers (graphic display software) to find, acquire and transfer information.
X
X.25:
Approved by the CCITT (now the ITU-T) in the 1970s as a popular standard for packet-switching networks. It defines standard physical layer, data link layer and network layers
(layers 1 through 3) of the OSI Reference Model. It was developed to describe how data passes into and out of public data communications networks. X.25 networks are in use
throughout the world.
Y
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Z
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