A
Automatic Number Identification (ANI)
A service that provides the telephone number of an incoming call. This is useful for a number of applications such as routing an 800 call to an appropriate vendor.

Application Service Provider (ASP)
Application Service Providers are organizations, institutions, or companies that manage and distribute software-based services and solutions to customers across a wide area network from a central data center.

Asymmetric Circuit
An asymmetric circuit is one in which traffic flowing in one direction is greater than that flowing in the reverse direction. This is useful for applications involving one-to-many, or "client-server," interactions such as video streaming.

An asymmetrical digital subscriber line, for example, is one which transmits video signals to terminals over existing telephone lines with signals returning from the terminals at 16 kb/s.
B
Backbone
A backbone is a main bus that connects two or more nodes together. In the context of telecommunications, it refers to a main cable that connects two or more network nodes together.

An Internet backbone, then, is the fiber optic cable link that connects two or more internet nodes together. If a telecommunications company is a backbone provider, it means that they likely build, operate, and maintain a high-speed, high capacity network.

Bandwidth
Bandwidth is one of those simple ideas that can get complex quickly. Simply put: it is the range of frequency within which a specific device functions.

If you can pack more cycles per unit of time (say, a second), you have a higher frequency. That means you have the potential to encode more information per second. Meanwhile, each frequency has the potential to be its own circuit or channel (think car radios and AM channels). So the bigger the bandwidth, the more frequencies and, potentially, the more information transmitted.

Broadband
Broadband (sometimes also called "wideband") is the property of any circuit that has a bandwidth greater than 4 kHz.

Burstable Bit Rate (BBR)
Burstable Bit Rate (BBR) is a guaranteed minimum capacity that allows data to be sent at high rates when network capacity is available.
C
C7 — An ITU-T common channel signaling standard
Signaling information relating to a multiplicity of circuits, and other information such as that used for network management, conveyed over a single channel by addressed messages.

Capacity
In telecommunications, capacity is a measure of maximum throughput and not storage. We might look at a bathtub and say it has a capacity of 500 liters; but a telecommunications engineer would look at the faucet and say it has a capacity of 50 liters per minute.

Carrier
In the telecommunications and internetworking industry, the term carrier has a specific meaning and refers to any company or corporation that offers to sell electromagnetic or photonic transmission services and that does some of the actual transmitting (called "carrying traffic") through operation of equipment and facilities. If a company does not do any of the actual transmission it is sometimes referred to as "Switchless" or "Reseller."

Call Detail Records
Call Detail Recording is a service feature in which call data on a specific telephone extension or group of subscribers are collected and recorded for cost-of-service accounting purposes.

In the days before computers and software (circa pre-1982), CDR used to be paper-based and labor intensive and, as a result, prohibitively expensive. Post-1981 it evolved into a cost-effective way to reduce fraud and improve the accuracy and speed of billing internally and to customers.

Circuit
A circuit is the complete path between two terminals over which one-way or two-way communications may be provided.

For more than 100 years—from the beginning of the telegraph up until electronic switching—a circuit was "dedicated" to its specific use (usually a voice phone call). Nothing could happen on the path (usually copper wire) until the call was completed. With the advent of computerized time multiplexing, however, it became possible to send more than one transmission over part of the same circuit. Circuits became "virtual" at that point, since the path was not the same for the entire length of the communication.

Calling Line Identification (CLID)
CLID, synonomous with ANI, is a service available on digital phone networks informing the party being called which number is calling them.

Compressed / Compression
When something (any message, data set, bitstream, or packet) is compressed it has been mathematically analyzed and reformatted to be transmitted in a shorter timespan. This is particularly useful in transmitting images where, for example, entire fields may be assigned mathematical properties instead of assigning 256 bits to each pixel. When a compressed message gets to its destination, it is deciphered or decompressed.

A bitstream that is not compressed at all is sometimes referred to as "raw."

Correspondent International Private Line (IPL) Service
Go Voice Correspondent International Private Line (IPL) Service is a high-speed link dedicated to the use of a single customer for integration of various applications including voice, data, facsimile, messaging, and video conferencing. This service is also commonly known as International Private Leased Circuit (IPLC) service, Half Circuit IPL, or Traditional IPL.

Customer Premise Equipment (CPE)
Customer Premise Equipment is any apparatus, including telephone handsets, private branch exchange (PBX) switching equipment, key and hybrid telephone systems, and add-on devices that are physically located on a customer's property. If CPE includes wiring (and it usually does), this is sometimes referred to as "on-premise wiring."
D
Domain Name System (DNS)
DNS is a service that translates domain names into IP addresses in much the same way as someone might find your telephone number by first referencing your name in the listings.

There is no single DNS database. DNS is actually a network of DNS servers that share information with each other.

Dynamic
A term most often used in identification, dynamic means taking some action and sending a signal. A dynamic signal sent prior to an anticipated event is called "proactive"; a dynamic query sent after an event is sometimes called "reactive." If a system is not dynamic it is usually called "passive."

Digital Signal Rate # (DS #)
DS is an international equivalence to the "T" standard used in the U.S. Thus:

DS-1 = 1.544Mb/s
DS-3 = 44.736Mb/s
DS-4 = 274.176 Mb/s

Unfortunately "T" does not always mean the same thing in the U.S. as elsewhere. The Japanese T4 standard, for example, is a digital signaling rate of 97.728 Mb/s.

Dual-tone Multifrequency (DTMF)
DTMF signaling is multifrequency signaling for telephone systems. DTMF uses standard and set combinations of two specific voice band frequencies, one from a group of four low frequencies and the other from a group of four higher frequencies.

DTMF signals, unlike dial pulses, can pass through the entire connection to the destination user, and therefore lend themselves to various schemes for remote control after the connection is established.
E
E1
E1 is a circuit with capacity of 2.048 Mb/s. E1 is a European standard widely used and is roughly the equivalent of a DS-1. However, E1 provides thirty 64 kb/s channels—six more than a DS-1.

Ethernet — a LAN protocol
A local area network LAN protocol was developed by Xerox Corporation in cooperation with DEC and Intel Inc. in 1976. Ethernet uses a "bus" or "star" topology and supports transfer rates of 10 Mb/s. The Ethernet specification served as the basis for the IEEE 802.3 standard, which specifies the physical and lower software layers. Ethernet uses the CSMA/CD access method to handle simultaneous demands. It is one of the most widely implemented LAN standards.

A later version of Ethernet, called 100 Base-T (or "Fast Ethernet"), supports data transfer rates of 100 Mb/s. The latest version, Gigabit Ethernet, supports data rates of 1 Gb (1,000 megabits) per second.
F
Fiber Optic (Cable)
Optical fiber is any filament of transparent dielectric material—usually glass or plastic, and usually circular in cross section—that guides light wave/particles. In tandem with LASER, it was one of the most important technologies invented in the 20th century that enables communications companies to transmit enormous amounts of data at the speed of light.

Single-mode fiber optic cable was first successfully deployed for profit by the U.S. corporation MCI in 1983. Since then its use has spread throughout the globe, both underground and underwater. Advances in light-repeating technologies and wavelength multiplexing have increased fiber optic capacity by an order of magnitude. Fiber optic cable, especially that made of plastic, is flexible, versatile, and long-lasting.
G
Global System for Mobile (GSM) Communications
Global System for Mobile (GSM) communications is a digital European cellular standard based on TDMA technology operating at 900MHz and developed to provide system compatibility across national borders. This compatible network enables GSM cellular users to use a single cellular phone throughout Europe, most of Asia, and parts of North and South America and have every call billed to one account.
I
Infrastructure
"Infrastructure" is one of those words designed to make a simple concept complicated. It means "how things are put together inside" or if you really want to get fancy, "how internal components relate to one another." (The knee bone is connected to the thigh bone. That's infrastructure for you.)

In the context of telecommunications, "infrastructure" has a specific meaning excluding external connections. A network has an infrastructure and it has interconnections to other networks. So how it is connected to the Internet, for example, is not part of its infrastructure.

Integrated
When two or more capabilities are offered using the same system—each capable of operating interdependently with no significant loss of speed or performance—that system is said to be integrated.

But what does that mean in practical telecommunications terms? It means that a network can offer different kinds of services over the same connections using the same protocols. For example, if voice signals are digitized and sent over a network using IP along with data and e-mail, then those services are "integrated."

International Private Line (IPL)
An international private line (IPL) is a service that involves dedicated circuits, private switching arrangements, and/or predefined transmission paths, whether virtual or physical, which provide communications between specific locations and across national boundaries.

International Private Leased Circuit (IPLC)
An International Private Leased Circuit is that which comprises an IPL package.

Full Circuit International Private Line (IPL) Service is a secure, high-speed dedicated connection provided between two international POPs, dedicated to the use of one customer. An IPLC is not subject to interference or congestion caused by other users' circuits or applications.

Internet Protocol (IP)
IP is a set of agreements and standards on how to address and ship packets of data. Most networks combine IP with a higher-level protocol called Transport Control Protocol (TCP). Together they are jointly referred to as TCP/IP.

The Internet Engineering Task Force sets IP standards. The current version of IP is version 4, abbreviated IPv4; the next generation of IP standards is version 6, which is abbreviated IPv6 or sometimes IPng.

Integrated Services Digital Network (ISDN)
ISDN is a network in which the same time-division switches and digital transmission paths are used to establish connections for different services including voice, data, e-mail, and fax.

International Toll-Free Service (ITFS)
International Toll Free Service (ITFS) is a fully automated, caller-dialed service option, which allows users to receive toll-free calls from 74 countries globally (as of the year 2000). These calls can be terminated to Teleglobe's customers at almost any location in the world. ITFS provides a cost-effective solution for applications such as calling card platforms, call center platforms, and business support applications.
L
Local Area Network (LAN)
A local area network (LAN) is any data communications system that lies within a limited spatial area, has a specific user group and a specific topology, and is not a public switched telecommunications network but may be connected to one. LANs are not necessarily subject to public telecommunications regulations.

LANs are usually restricted to relatively small areas, such as rooms, buildings, ships, and aircraft. An interconnection of LANs within a limited geographical area, such as a military base, is commonly referred to as a campus area network. An interconnection of LANs over a city-wide geographical area is commonly called a metropolitan area network (MAN). An interconnection of LANs over large geographical areas is commonly called a wide area network (WAN).

Latency
Latency means delay or waiting time. Latency is a period of time between an access request and approval. In the case of a router, it is the amount of time that elapses between receiving and retransmitting a local area network (LAN) data packet.
M
Multiplexer (MUX)
A multiplexer combines multiple inputs into an aggregate signal to be transported via a single transmission channel. Multiplexing is a technique first invented for copper-wire-based telephone systems as a way of sending more messages through a limited capacity line. However its true potential was realized with its application to fiber optics, where messages could be multiplexed over individual frequencies of light.
N
Network
If three or more entities are communicating, they are said to be networked.

In practical telecommunications terms, a network refers to the entire technical apparatus—all of the equipment, facilities, software, computer hardware, and operating personnel—that enables modern communications to take place by electromagnetic or photonic means.

If three or more networks are networked, this is referred to as "internetworking," from which the name "Internet" was derived.

Node
A location for processing (such as a computer) somewhere in a network. Every node has a unique network address.
O
Optical Carrier Speed # (OC-#)
OC is a specification of speed of a fiber optic network conforming to the SONET standard.

OC-1 = 51.85 Mb/s
OC-3 = 155.52 Mb/s
OC-12 = 622.08 Mb/s
OC-24 = 1.244 Gb/s
OC-48 = 2.488 Gb/s
OC-96 = 4.976 Gb/s
OC-192 = 9.953 Gb/s

Out Of Band
Any frequency outside the band used for voice frequencies is known as "out of band."

Out-of-band signaling refers to the use of transmission facilities other than the primary channel bandwidth for simple transmission control pulses.

OOB is also the use of narrow band filters to place a voice signal on a carrier channel below 3,400 Hz, reserving the 3,400—3,700 Hz band for supervisory signals.

P
Packet
A packet is a sequence of bits that is transmitted and switched as a whole set. This set of 0s and 1s is arranged in a specific format (called packet format), which includes data and control signals and possibly error control information.

Packet switching has the advantage of making virtual circuits possible, thereby improving network capacity. With packet switching, a channel is occupied only during the transmission of the packet and after this transmission is complete the channel becomes available for other packets sent to the same destination or elsewhere.

Peak Load
Peak load means the maximum capacity of a network to carry traffic at any given point in time.

Typically most networks don't operate at or beyond peak load very often. In fact, engineers get nervous when normal (or average or mean) traffic usage even approaches peak load. This is because when a network is overloaded, its performance degrades.

There are basically two ways to handle over peak load situations. The first is to design a network for graceful failure so that most traffic gets through while only some is delayed. The second is to reserve extra capacity on somebody else's network and let them carry the extra traffic.

Pipes
A pipe is a slang term, used commonly among English-speaking electrical engineers, for any conduit that carries telecommunications services. The term is borrowed directly from an older civil engineering tradition of building and maintaining water, gas, and sewage lines.

In the context of telecommunications, a small pipe is one with very limited capacity (e.g. 28 Kb/s), and a huge pipe is one with very large capacity (e.g. 9.953 Gb/s).

Point of Presence (POP)
A point of presence (POP) is a physical layer within a local access and transport area (LATA) at which an inter-LATA carrier establishes itself for the purpose of obtaining LATA access and to which the local exchange carrier (LEC) provides access services.

Provider
It should come as no shock that a provider supplies or provides telecommunication services to a customer. Once upon a time there was no distinction among providers, carriers, resellers, or any other specialization. Now that things have become more complicated, the telecommunications industry needed a word to summarize the concept of full-service contracting.

Provisioning
Provisioning means establishing and acquiring one or more telecommunication services, from the submission of the requirement through the activation of the service(s) including all associated conduits and equipment. "Provisioning" and "Initiation" are synonymous and include altering the state of an existing priority service or capability.

Public Switched Telephone Network (PSTN)
A public switched telephone network (PSTN) is an intranational (sometimes called domestic) telecommunications network usually accessed by telephones, key telephone systems, private branch exchange trunks, and data arrangements. Completion of a circuit between the call originator and the call receiver in a PSTN requires network signaling in the form of either dial pulses or multifrequency tones.

Q
Quality of Service (QoS)
Quality of Service (QoS) means that an ATM provider guarantees to its customers that the amount of time it takes a packet to travel from source to destination will not exceed a specified level.
R
Redundant
Redundancy is the tradeoff of resources for risk, in which two or more identical parts or subsystems are employed to insure that there is no total system failure.

Redundancy is also the tradeoff of cost in return for capability when two identical parts or subsystems are employed to improve the overall capacity or speed of the system.

Reseller
Almost every industry has resellers—people who buy commodities at one price and then sell them to someone else at a higher price, and telecommunications is no exception.

Telecommunications reselling happens for four main reasons. First of all, sometimes the owner and/or operator of a network finds that it has more capacity than it needs to handle its own traffic — often the case when a new cable or channel first opens. Rather than let extra capacity go to waste, the owner obtains some revenue by selling the capacity at a bulk discount to a reseller. Secondly, sometimes a network owner/operator doesn't want to be in the business of selling directly to customers, and prefers to let someone else handle the daily grind of customer service. Thirdly, building and maintaining a network is expensive and some companies would prefer to be in the business of reselling only and not have to worry about managing a network. And lastly, some network owners/operators want to buy or lease extra network capacity from time to time to avoid over peak load situations for their own customers.

Route / Router
Using internetworking protocols, each IP packet takes a different route to get to its destination. This route, or path, may include many gateways and many physical networks.

Computerized hardware that sends packets on their way are called routers.
S
Scalable (Scalability)
An architecture, format, or process is said to be scalable if it can be physically enlarged or expanded while retaining the same shape and substance or internal structure.

Scalability is probably one of the most fundamental ideas "and sought-after effects"— in the business world. Happily, networking is an industry that lends itself to scalability. A process that works for one node and for one module can be repeated anywhere, and the benefit of linking nodes together to stimulate use is greater than the cost of building the interconnection among nodes in the first place.

Synchronous Digital Hierarchy (SDH)
SDH is an international standard for synchronous data transmission over fiber optic cables. The North American equivalent of SDH is SONET. SDH defines a standard rate of transmission at 155.52 Mb/s, which is equivalent to a rate of OC-3.

Server
A server is a network device that provides service to the network users (or "clients") by managing shared resources.

A new trend in telecommunications in the last few years is client-to-client networking where centralized servers are bypassed entirely. With client-to-client networking, every PC has the potential to be a server.

SS7 — ANSI's common channel signaling standard
Signaling System No. 7 (SS7) is a common-channel signaling system defined by the ITU-T (actually, the old CCITT in its 1988 Blue Book Recommendations Q.771 through Q.774, to be precise) and is a prerequisite for implementation of an Integrated Services Digital Network. SS7 is an addressing protocol that speeds up call processing by operating "out of band." It enables fraud detection, caller ID, store and forward, ring back, concurrent data, and other features.
T
T1 Digital Multiplexer (T1DM)
T1 once had a specific meaning as 24 voice channels, each digitized at 64 kb/s, combined into a single 1.5 Mb/s stream, carried over two pairs of regular copper telephone wires. Now it generally refers to any service that offers 1.5 Mb/s capacity.

A T1DM is a device that multiplexes 23 channels of 64 kb/s signals into one 1.544 Mb/s signal. The remaining time slot (channel 24) is used for administrative data.

T3
T3 means transmission capacity of 44.736 Mb/s. A T3 is the equivalent of 28 multiplexed T1 channels.

Time Division Multiplexing (TDM)
TDM is a transmission process in which bits belonging to different messages are transmitted at successive times on the same channel. TDM technology enables the sequential transmission of a number of signals over a single common path.

Traffic
Traffic is the total quantity of messages and their length that moves over a specific channel during a specified period of time. Traffic can be quantified in a variety of ways depending upon the mechanisms used to carry it. For example, a channel could be said to carry "256 simultaneous voice calls." This is different from capacity, which is the maximum rate at which messages or bits can flow through a specified channel. Where traffic flow approaches peak load, the "smart" network attempts to reroute traffic to lesser-used portions of the network or apply some other technology such as caching.
U
Uninterruptible Power Supply (UPS)
A UPS is an auxiliary (or "backup") battery that supplies continuous power in the event of a power loss from the power grid. Since all battery systems run down eventually, a UPS guarantee usually means someone had the foresight to buy an electrical power generator and store enough fuel to recharge the batteries.
V
Voice Access Over Internet Protocol (VOIP)
VOIP is a newer term for Internet Telephony. It means exactly what it describes: a way to send voice messages using IP addressing. VOIP makes distinctions such as "local" and "long distance" phone calls meaningless.

Virtual Private Network (VPN)
A VPN is a switched network with special services such as enabling customers to call between offices in different area codes or nations while dialing a minimum of digits. Carriers are enhancing VPN service offerings by combining inbound and outbound services under one package.
W
Wide Area Network (WAN)
A wide area network (WAN) is any data communications system that lies within a very large geographic area or region such as a state or territory, has a specific user group and a specific topology, and is not a public switched telecommunications network but may be connected to one.
Z
Zero Packet Loss
When a network is congested, there is a higher probability that packets of data in any given message will be lost (i.e. not delivered within a given time frame). This can mean that the entire message would need to be re-transmitted, resulting in time delay and potentially more congestion.

Advanced protocol software can reduce the actuality of packet loss to zero, with only a minor slowing of delivery speed, easing congestion and improving overall performance.