Glossary of Terms

No other industry speaks in acronyms as much as the Telecom Industry because it is like learning a foreign language,  and we are providing the translation.

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

ABR (Available Bit Rate)
An ATM service class that supports VBR data traffic with average and peak traffic parameters serving remote procedure calls, distributed file services, and computer process swapping and paging.

ACK (Acknowledge Character)
A transmission that affirms response to the connecting station and is also used for accuracy testing.

ADM (Add/Drop Multiplexer)
A device that facilitates adding and dropping of data payload by reducing the level of the signal.

ADPCM (Adaptive Differential Pulse Code Modulation)
Encoding technique that allows analog voice signals to be carried on a 32Kbps digital channel.

ADSL (Asymmetrical Digital Subscriber Line)
The high bandwidth use over conventional twisted-pair local loop lines that enables multimedia based applications such as video-on-demand.

AES (Advanced Encryption Standard)
The encrypted algorithm used to transmit sensitive (not classified) U.S. government data.

AIN (Advanced Intelligent Network)
Second generation networks pioneered by Bellcore that establishes a uniform architectural platform for all carriers.

AIP (Application Infrastructure Provider)
Management of data center servers, databases and switches.

AM (Amplitude Modulation)
Variation of a carrier signal’s amplitude from 0 to 1 bit.

ANI (Automatic Number Identification)
Display of a caller’s telephone number also called Caller ID.

ANSI (American National Standards Institute)
Organization that sets the standards for transmission codes, protocols, media, and high-level languages, plus others.

ANSI X12
U.S. standard for electronic data interchange.

API (Application Programming Interface)
Operating system low-level services.

ARQ (Automatic Repeat Request)
Resending of data block when errors are detected.

AS (Autonomous System)
System including gateways and networks managed by a single administrator.

ASCII (American Standard Code for Information Interchange)
A 128-character code used to exchange data between processing and communication systems.

ASP (Application Service Provider)
Supplier of applications, generally paid.

ATM (Asynchronous Transfer Mode)
High-bandwidth, fast packet-switching and multiplexing technique supporting high-capacity suitable for multiservice connections.

AUI (Attachment Unit Interface)
Connecting device to Ethernet transceiver.

B/D link (Bridge/Diagonal Link)
Link between two mated pairs of STP.

BECN (Backward Explicit Congestion Notification)
A bit in the Frame Relay header that signals network congestion.

BER (Bit Error rate)
The ratio between the bits transmitted and the bits receivedsmission, usually expressed as number referred to a power of 10 (e.g., 1 bit error in 105 bits transmitted, or 1 in 100,000).

BGP (Border Gateway Protocol)
A gateway protocol that allows routers to communicate with each other. BGP is an exterior routing protocol used between autonomous systems and is of concern to service providers and

bps (Bits Per Second)
A measure of the amount of transmission capacity available.

BRA (Basic Rate Access)
The interface to the basic rate used in ISDN.

BRI (Basic Rate Interface)
Another term for the interface to the basic rate used in ISDN.

CA (Certificate Authority)
Third-party organization that issues digital certificates guaranteeing ownership.

CAP (Carrierless Amplitude Phase) modulation
Single-carrier modulation used in early generations of ADSL.

CBQ (Class-Based Queuing)
Open, nonproprietary technology that prioritizes data between  the CoS to IP network infrastructures.

CBR (Constant Bit Rate)
Highest ATM service class available providing guaranteed data delivery.

CC7 (Common-Channel Signaling System 7)
Signaling protocol used in high-speed digital networks to communicate between intelligent network nodes.

CCIS (Common-Channel Interoffice Signaling)
An electronic means of signaling between any two switching systems independent of the voice path. The use of CCIS makes possible new customer services, versatile network features, more flexible call routing, and faster connections.

CD-ROM (Compact Disc-Read Only Memory)
Storage device in computer systems.

CDDI (Copper-Distributed Data Interface)
A version of FDDI that runs on UTP cabling rather than on fiber-optic cable.

CEPT (Commission of European Post and Telecommunications)
European PTT organization dealing with operational and tariff matters.

CHAP (Challenge Handshake Authentication Protocol)
Verification protocol using a three-way handshake confirm the identity of the peer throughout a connection.

CIDR (Classless Interdomain Routing)
IP addressing protocol that allocates large blocks of contiguous Internet addresses.

CIR (Committed Information Rate)
Bandwidth a user can expect from a Frame Relay carrier.

CLEC (Competitive Local Exchange Carrier)
A telephone company focused on dial tone to business customers.

CMIP (Common Management Information Protocol)
OSI management information protocol for networks.

CMISE (Common Management Information Services)
Standardized service interface created by ISO to manage heterogeneous networks.

CO (Central Office)
Physical plant where switching equipment is located.

coax (coaxial cable)
One or more central wire conductors protected by a dielectric insulator and encased in wire mesh or extruded metal sheathing.

codec (coder-decoder)
Device that converts analog signals.

COPS (Common Open Policy Services)
Query-response protocol addressing how servers and clients on a network exchange policy information.

CoS (Class of Service)
A categorization of subscribers or traffic based on priority levels.

CPE (customer premises equipment)
Equipment at the customer site owned and managed by the customer.

CRC (Cyclic Redundancy Check)
Highly effective error-detecting using a series of two 8-bit block-check characters incorporated into the transmission frame that are checked at the receiving end.

CSMA (Carrier Sense Multiple Access)
LAN access that senses transmission activity on a shared channel and defers transmission while channel is active.

CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance)
Network traffic control system that averts data collision.

CSMA/CD (Carrier Sense Multiple Access/Collision Detection)
LAN protocol that allows stations to detect interference caused by simultaneous transmissions.

CSU (Channel Service Unit)
Termination point of a leased line or T-1/E-1 facility at the customer site.

CTS (Clear To Send)
Control circuit that indicates to data terminal equipment that data can or cannot be transmitted.

CVSD (Continuous Variable Slope Delta Modulation)
Speech encoding and digitizing that uses 1 bit to describe the difference in slope of the curve between two samples.

CXR (Carrier)
Data transmission with a specific set of characteristics, i.e. frequency.

DAMA (Demand Assigned Multiple Access)
Allocation system for satellite to earth stations.

dB (Decibel)
A unit of measurement 10 x the logarithm (base 10) of the ratio of the power of two signals.

DCE (Data Communications Equipment)
Equipment that interfaces between the DTE and the carrier’s networks.

DCLEC (Data-Competitive Local-Exchange Carrier)
A carrier focused on data services, i.e. DSL services.

DCS (Digital Cross-Connect System)
Device that enables the reconfiguration of a digital network depending on congestion or failure in the network.

DDS (Digital Data Service)
Digital transmission with speeds up to 56Kbps/64Kbps.

DEN (Directory Enabled Networking)
Microsoft and Cisco established this system to store information about users, devices, servers, and applications in a common repository.

DES (Data Encryption Standard)
Algorithm designed by the National Bureau of Standards to encipher and decipher data using a 56-bit key.

DID (Direct Inward Dialing)
Dial into an exchange network to specific station lines without attendant assistance.

DiffServ (Differentiated Services)
Prioritization model in networks providing preferential allocation of resources based on traffic classification.

DLC (Digital Loop Carrier)
Remote concentrator or remote terminal not interoperable with some of the new DSL offerings.

DLCI (Data-Link Connection Identifier)
Identifier in a Frame Relay header.

DLI (Data-Line interface)
The connection point of a data line to a telephone system.

DMT (Discrete Multitone)
Multicarrier modulation used in ADSL.

DNS (Domain Name System)
Protocols and databases that distinguish Internet website names and physical IP addresses.

DPNSS (Digital Private Network Signaling System)
European standard for signaling between PBXs.

DQDB (distributed Queue Dual Bus)
Media access standard for metropolitan area networks.

DS (Digital Signal) level
North American standard increments of the PDH hierarchy.

DSI (Digital Speech Interpolation)
Digitized speech cut into slices that transmit during speech; transmission stops when person is silent.

DSL (Digital Subscriber Line)
Broadband technologies that pack data onto copper wires.

DSLAM (DSL Access Multiplexer)
Device at a carrier’s central location that links DSL to a single high-speed ATM line.

DSSS (Direct Sequence Spread Spectrum)
Data bits are converted to a series of 10 to 144 transmitted bits or chips.

DSU (Digital or Data Service Unit)
Synchronous serial data interface that controls the flow of data and converts incompatible data between a digital terminal and the CSU.

DTE (Data-Terminating Equipment)
Equipment that supports end-user applications as data is transmitted between two points.

DTMF (Dual-Tone Multifrequency) Signaling
Operation of pushbutton telephone sets.

DVB (Digital Video Broadcasting Group)
European organization specifying digital signals in satellite and cable broadcasting.

DWDM (Dense Wavelength Division Multiplexing)
Optical technology used to increase bandwidth over fiber-optic backbones.

E (Extended) link
Link that enhances reliability from SSP to a second STP pair.

e-commerce (electronic commerce)
Goods and services sold and purchased online.

e-mail (electronic mail)
Send and receive messages and files over computer networks.

EBCDIC (Extended Binary-Coded Decimal Interchange Code)
Code with 256 possible combinations to relay data.

eBIP (e-Business Infrastructure Provider)
Provider of web-based solutions to small businesses.

Ebps (Exabits Per Second)
One billion Gbps.

EDFA (Erbium-Doped Fiber Amplifier)
Optical amplifier using erbium injected into fiber and operating at 10Gbps.

EDI (Electronic Data Interchange)
Asynchronous exchange of intercompany documents from computer to computer.

EGP (Exterior Gateway Protocol)
Routing protocol to exchange data between organizational networks.

ELEC (Ethernet Local Exchange Carrier)
Provider specializing in Ethernet solutions.

ERL (Echo Return Loss)
Echo currents on one end of the call caused by telephone circuits operating on the other end.

ESCON (Enterprise Systems Connection)
Proprietary optical networking.

ESP (Encapsulated Security Payload)
Security using encrypted IP datagram data.

ESS (Electronic Switching System)
Mechanism that switches telephone calls.

ETSI (European Telecommunication Standards Institute)
Telecommunications standardization organization.

even parity check & odd parity check
Test to assess whether the number of digits in a binary group digits is even or odd.

F (Fully Associated) link
Link that connects to signaling endpoints, usually SSPs.

FDD (Frequency Division Duplexing)
Technique of using different portions of the frequency band when synchronization between the base stations is not possible.

FDDI (Fiber Distributed Data Interface)
100Mbps, fiber-based token-passing ANSI standard with dual fiber-optic counter-rotating rings capable of supporting 100Mbps data rates each.

FDM (Frequency-Division Multiplexing)
Dividing bandwidth of a communications line into multiple smaller units.

FDMA (Frequency Division Multiple Access)
Users in an analog cell system are assigned to different frequencies.

FECN (forward explicit congestion notification)
A bit in the Frame Relay header that detects and reports network congestion.

FEP (Front-End Processor)
Dedicated communications system that intercepts and handles activity for the host.

FHHS (Frequency Hopping Spread Spectrum)
Frequency hopping in a known pattern.

FIFO (First In, First Out)
Queuing technique that ensures the first cell out has been in line longest, ensuring data organization.

FM (Frequency Modulation)
One of three possible ways to modify a sine wave signal to carry digital bits.

FSK (Frequency Shift Keying)
Modulation using two different frequencies to distinguish between a mark (digital 1) and a space (digital 0) when transmitting on an analog line.

FTAM (File Transfer Access and Management)
An application layer standard defining the correct way to create, delete, read, and change file attributes as well as transfer and access files stored remotely.

FTP (File Transfer Protocol)
Process enabling computer user to get files from another computer, or to send files to another computer.

FTTC (Fiber-To-The-Curb)
The cable that runs from a switching office to a point on the street grid.

FTTH (Fiber-To-The-Home)
A system in which fiber cable extends from a switching office to the subscriber’s house.

FX (Foreign Exchange) line
A line that makes a toll call appear to be a local call.

GHz (Gigahertz)
1 billion cycles per second.

HAN (Home Area Network)
A broadband network in a smart house that connects the various smart devices.

HDLC (High-Level Data Link Control)
Communications line control that uses a specified series of bits to control data transmission.

HDSL (High-Bit-Rate DSL)
Long distance bandwidth that extends 2.2 miles, delivering symmetrical service (in both directions.)

HFC (Hybrid Fiber Coax)
Fiber backbone networking that supports traditional telephony, broadcast video, and interactive broadband services.

HIPPI (High Performance Parallel Interface)
A gigabit-per-second OSI Layer 1 and 2 interface standardized by ANSI that can be extended up to several miles using fiber-optic technology.

HSSI (High-Speed Serial Interface)
Interface between a high-speed router or similar device, and a DCE.

HTTP (Hypertext Transfer Protocol)
Standard mechanism used in Internet transfer of documents between server and client systems.

Hz (Hertz)
Unit of electromagnetic frequency equal to one cycle per second.

I-frame (Intracoded Frame)
Frame that is not reconstructed from another frame but is a reference frame.

I/O (Input/Output)
Devices or channels involved in an input process, and, alternately, in an output process.

ICANN (Internet Corporation for Assigned Names and Numbers)
Formed in 1998 to assume control of management of domain name and root server systems previously managed by U.S. government.

ICMP (Internet Control Message Protocol)
Internet Protocol to oversee error and control messages, i.e. delivery or notice delivery has failed.

ICP (Internet Content Provider)
Provider specializing in content.

IDEA (International Data Encryption Algorithm)
Free algorithm for noncommercial use in PGP and in Speak Freely.

IDF (Intermediate Distribution Frame)
Frame with distributing blocks on both sides that interconnects telephone circuitry.

IDSL (ISDN DSL)
Transmission medium with maximum loop length of 3.4 miles.

IETF (Internet Engineering Task Force)
Nonprofit organization that sets standards used in TCP/IP and the Internet.

IFRB (International Frequency Registration Board)
Board responsible for maintenance of the international list of radio frequency use and allocation of new frequencies.

IGMP (Internet Group Membership Protocol)
Protocol that allows Internet hosts to multicast.

IGP (Interior Gateway Protocol)
Protocol used to propagate network reachability and routing information.

IGRP (Interior Gateway Routing Protocol)
Cisco-developed protocol that directs each router to update at regular intervals.

IKE (Internet Key Exchange)
Protocol used by IPSec, a simplified form of key exchange.

ILEC (Incumbent Local Exchange Carrier)
Local service provider before Telecommunications Act of 1996 was enacted, i.e. the Baby Bells.

IMUN (International Mobile User Number)
A number used to dial a subscriber in third-generation mobile networks.

IN (Intelligent Network)
Architecture for providing advanced network services.

IntServ (Integrated Services)
Support over IP networks is a service model that best controls end-to-end packet delays.

IP (Internet Protocol)
Protocol that specifies the exact format of all data as it travels through a TCP/IP network.

IPDC (Internet Protocol Device Control)
Specification for flexible management of media gateway devices.

IPNSIG (Interplanetary Internet)
The architecture and protocols to permit interoperation of the Internet on earth with other remotely located internets in space.

IPS7 (IP Signaling System 7)
Signaling protocol that works with SS7.

IPSec (IP Security)
Protocols to support secure exchange of packets.

IPv4 (Internet Protocol Version 4)
Current IP in which an IP address has the network ID and the host ID.

IPv6 (Internet Protocol Version 6)
IP addressing using a 128-bit address which equals 340 billion billion billion billion unique addresses.

IPX (Internetwork Packet Exchange)
Novell equivalent of IP to route NetWare packets between LANs.

IrDA (Infrared Data Association)
Short-range wireless connection between devices using infrared links.

IRP (Interdomain Routing Protocol)
ISO is considering as the basis for inter AD routing protocol.

IS-IS (Intermediate System to Intermediate System)
Emerging IS-IS protocol uses a link state algorithm to provide routing services for TCP/IP and OSI.

ISC (International Switching Center)
Exchange to switch traffic between countries over international circuits.

ISDN (Integrated Services Digital Network)
Access technology that is circuit-switched digital subscriber line service,

ISO (International Organization for Standardization)
Organization promoting standards to facilitate the international exchange of goods and services.

ISV (Independent Software Vendor)
Vendor developing applications.

IXC (Interexchange Carrier)
Long-distance telephone carrier with circuit-switched, leased-line, or packet-switched service.

JPEG (Joint Pictures Expert Group)
International standard for still image compression.

JTACS (Japanese Total Access Communication Systems)
Japanese wireless system in the 800MHz to 900MHz band.

Kbps (Kilobits Per Second)
1,000 bits/second.

KHz (Kilohertz)
1,000 cycles/second.

L2TP (Layer 2 Tunneling Protocol)
Protocol that can work in a non-IP enterprise environment like VPN over a backbone.

LAN (Local Area Network)
A limited area network that is small, i.e. office building.

LANE (LAN Emulation)
ATM Forum standard for LAN across an ATM network.

LAPB (Link Access Protocol Balanced)
Link-level protocol for reliable transfer of a packet from a host to an X.25 packet switch.

laser (light amplification by simulated emission of radiation)
Infrared lasers are widely used in fiber-optic communications, particularly long-haul links.

LATA (Local Access and Transport Area)
Geographic regions in the United States in which the Bell operating companies offer local calling, private lines, and more.

LCD (Liquid Crystal Display)
Graphic display on a terminal screen using an electroluminescent technology.

LDAP (Lightweight Directory Access Protocol)
Standard directory server technology for the Internet.

LDP (Label Distribution Protocol)
MPLS signaling protocol.

LEC (Local Exchange Carrier)
Incumbent local telephone company.

LED (Light-Emitting Diode)
Semiconductor junction diode that emits radiant energy and is used as a light source for fiber-optics communications, particularly for short-haul links.

LLC (Logical Link Control)
Protocol by the IEEE 802 that is common to all of its local network standards.

LMDS (Local Multipoint Distribution Service)
Technique for supplying broadband access via a point-to-point microwave digital system.

LMI (Local Management Interface)
Frame Relay for exchanging status information between the bridge or router and the network.

LPC (Linear Predictive Coding)
Vector-quantization-based compression scheme for speech.

LSR (Label-Switching Router)
MPLS-enabled router and/or MPLS-enabled ATM switch.

m-commerce (mobile commerce)
Financial transactions conducted on mobile devices.

MAC (Media Access Control)
Part of OSI Layer 2 that describes how devices share access to the network.

MAE (Metropolitan Area Exchange)
Interconnection and exchange point where public Internet backbones meet and exchange traffic.

MAN (Metropolitan Area Network)
Network spanning up to 62-miles, enough to be citywide.

MAPI (Messaging Application Programming Interface)
Microsoft app provides hooks to various messaging systems, so developers can create message-enabled applications by writing those applications to Simple MAPI.

MAU (Media Attachment Unit)
Transceiver connecting the AUI port of an Ethernet interface card to data communications

MB (Megabyte)
1,048,576 bytes.

mbone (Multicase Backbone)
Trial to upgrade the Internet to manage live multimedia messages.

Mbps (Megabits Per Second)
1,048,576 bits per second.

MBS (Mobile Broadband Services)
High bit-rate (100Mbps+) over wireless channels.

MCU (Multipoint Control Unit)
Videoconferencing hub device.

MD5 (Message Digest-5)
Created in 1991, this algorithm is used to build digital signatures.

MDF (Main Distribution Frame)
Structure to support terminal strip connections and wiring arrangements outside and inside telephone exchange circuitry.

MEGACO (Multimedia Gateway Control)
Emerging ITU standard for media gateways.

MGCP (Multimedia Gateway Control Protocol)
Soft switches provide external control and management of gateway.

MHz (Megahertz)
Frequency equal to one million cycles per second.

MIB (Management Information Base)
How data is stored, monitored, and managed in an SNMP device.

MIDI (Musical Instrument Digital Interface)
Standard defining coding musical scores.

MIME (Multipurpose Internet Mail Extensions)
Internet standard enabling a message to contain textual, binary, or arbitrarily formatted data.

MMDS (Multichannel Multipoint Distribution Service)
Technique for supplying broadband access via a point-to-point microwave digital system up to 30 miles wide.

modem (modulator-demodulator)
Device installed at each end of an analog communications line between computer and destination.

MPLS (Multiprotocol Label Switching)
Integration of Layer 2 and Layer 3 network links to simplify and improve IP-packet exchange.

MPlS (Multiprotocol Lambda Switching)
Specific wavelengths that make it possible for routers and switches to perform necessary functions automatically.

MPOA (Multiprotocol over ATM)
ATM Forum standard allowing multiple local networks with differing protocols to link across an ATM backbone.

mrouter (multicast router)
Router that packages IP packets and forwards them to their destination.

MSAU (Multistation Access Unit)
Device that enables LAN workstations to be cabled in a star configuration.

MSP (Management Service Provider)
Provider that manages and monitors a network.

MSPP (Multiservice Provisioning Platform)
Device that can manage data protocols and interfaces.

MSU (Modem Sharing Unit)
Device that permits two + terminals to share a modem.

MTBF (Mean Time Between Failures)
Average time the system works without fault.

MTS (Mobile Telephone Service)
Telephone service provided between mobile stations and the public switch telephone network via radio transmission.

MTSO (Mobile Telephone Switching Office)
Cellular radio system linking base transceivers with the terrestrial local exchanges.

MTTR (Mean Time To Repair)
Average time to perform repair a failed device.

MTU (Maximum Transmission Unit)
The maximum packet size that can be transmitted over a LAN or an internet.

N-ISDN (Narrowband ISDN)
Introduced in 1983, this network architecture and standards provide high-quality, error-free transmission to public telephone networks worldwide.

NACK or NAK (Negative Acknowledgment)
Error message indicating block needs to be re-sent before anything else can happen.

NAP (Network Access Point)
Point where backbones interconnect to exchange traffic between providers.

NCP (Network Control Program)
Program that controls the communications operations.

NetBIOS (Network Basic Input/Output System)
Interface used in PC networks.

NIC (Network Interface Card)
Component that connects a station to a network.

NIOD (Network Inward/Outward Dialing)
System that enables dialing between a toll network and/or a local network.

NLSP (NetWare Link Services Protocol)
Protocol with low network overhead and rapid convergence.

NMC (Network Management Center)
Network control center.

NPA (Numbering Plan Area)
A geographic subdivision of the territory covered by a national or integrated numbering plan. An NPA is identified by a distinctive area code.

NRZ (Non-Return To Zero)
Signaling at a constant level for a specific period of time.

NSP (Network Service Provider)
Large carrier that owns its own infrastructures, i.e. Qwest.

NTU (Network Terminating Unit)
Network equipment that connects to the data terminal equipment.

OADM (Optical Add/Drop Multiplexer)
Device used to convert between light and electricity in a nonoptical multiplexer.

OC-1 to OC-48 (Optical Carrier-1 to Optical Carrier-48)
Base optical carrier transmission speed of 51.840Mbps.

OFDM (Orthogonal Frequency Division Multiplexing)
Multicarrier broadcast over many frequencies, reducing interference.

OGT (Out-Going Trunk)
One-way trunk carrying outbound traffic.

OLT (Optical Line Termination)
Switch that sends traffic downstream and upstream.

ONP (Open Network Provision)
Standard for European telecommunications network infrastructure.

ONU (Optical Network Unit)
Device in which optical-to-electrical conversion occurs.

OPX (Off-Premises Extension)
Phone extension located apart from main switch.

OSI (Open Systems Interconnection)
Logical network architecture used to enable an OSI compatible computer to communicate with any other OSI-complaint computer.

OSP (Online Service Provider)
Provider using intuitive navigation to organize online content.

OSPF (Open Shortest Path First)
Routing network protocol delivering lowest cost and multiplath routing plus load balancing.

OTDR (Optical Time Domain Reflectometer)
Device used in fiber networks to detect potential leaks, possibly hackers.

P-frame (Predicted Frame)
Reference frame, per MPEG terminology.

PABX (Private Automatic Branch Exchange)
Term for PBX.

PAD (Packet Assembler/Disassembler)
Conversion device that converts serial data stream into packets to send across a packet-switched network.

PAL (Phase Alternate Line)
Western Germany and the United Kingdom’s color television broadcasting system.

PAM (Pulse Amplitude Modulation)
Pulse carrier amplitude variation in succession.

PAN (Personal Area Network)
Individual network between badge-based computers and devices.

PAP (Password Authentication Protocol)
Protocol to confirm authentic identity using a two-way handshake throughout duration of communication.

Pbps (Petabits Per Second)
1,000Tbps.

PBX (Private Branch Exchange)
Telephone switch on customer premise offering extensions for telephone network.

PCM (Pulse Code Modulation)
Conversion of an analog voice signal into a digital bitstream for transmission.

PCS (Personal Communication Services)
Digital service that operates in the 1.8GHz to 2GHz band.

PDC (Personal Digital Cellular)
This Japanese Digital Cellular (JDC) is commonplace in Japan.

PDH (Plesiochronous Digital Hierarchy)
First generation digital ordering system that defines available digital transmission rates and number of channels.

PDN (Public Data Network)
Packet-switching network designed to deliver low error-rate data transmission.

PDU (Protocol Data Unit)
Term for a packet.

PGP (Pretty Good Privacy)
PGP encrypting is one of the most common ways to protect messages on the Internet because it is free, easy to use and has proven to be effective.

PHS (Personal Handyphone System)
Japanese 2G PCS wireless networks.

PING (Packet Internet Groper)
The program used to test reachability in TCP/IP Internet destinations.

PKE (Public Key Encryption)
Message authentication used on most web browsers.

PKI (Public Key Infrastructure)
Secure e-business application.

PLP (Packet Layer Protocol)
Standard network layer of X.25.

PM (PhaseModulation)
Method of modifying a sine wave signal to carry information.

PNAP (Private Network Access Point)
Private point of access to the Internet.

PON (Passive Optical Network)
One access line in a network shared among multiple buildings.

POP (Point Of Presence)
Physical access location into network.

POTS (Plain Old Telephone Service)
Standard analog telephone service in most residences.

PPP (Point-to-Point Protocol)
Router-to-router and host-to-network connections over synchronous and asynchronous circuits.

PPTP (Point-to-Point Tunneling Protocol)
A Layer 2 protocol that works in a non-IP enterprise environment used by customers with a need for multiple protocols instead of just IP.

PRI (Primary Rate Interface)
Bundled ISDN circuits used primarily as a PBX interface.

Proxy ARP (Proxy Address Resolution Protocol)
Router answers ARP requests intended for another by supplying its own physical address.

PSK (Phase-Shift Keying)
Transmitting digital information to analog in varying phases of a carrier signal.

PSTN (Public Switched Telephone Network)
Traditional public telephone system end-to-end.

PT&T (Postal, Telegraph, and Telephone) Organization
Government common carrier.

PTO (Public Telecommunications Operator)
Incumbent carrier outside the United States.

PVC (Permanent Virtual Circuit)
Dedicated private line between users in a packet switching network.

PWM (Pulse Width Modulation)
Encoding information using variations of carrier pulses.

QAM (Quadrature Amplitude Modulation)
Single-carrier modulation of amplitude and phase to yield higher spectral efficiency.

QoS (Quality of Service)
Applications indicate specific requirements to the network before transmitting data.

QPSK (Quadrature Phase Shift Keying)
Single-carrier modulation supporting 2 bits/symbol time.

RADIUS (Remote Authentication Dial-in User Services)
Authentication and access control server limiting user access of corporate resources.

RADSL (Rate-Adaptive DSL)
Symmetrical or asymmetrical transmission that is highly adaptable to accommodate rates from 600Kbps to 7Mbps downstream and from 128Kbps to 1Mbps upstream.

RAM (Random-Access Memory)
Computer memory that can be accessed without touching preceding bytes.

RARP (Reverse Address Resolution Protocol)
Protocol to identify an IP address from the server.

RBOC (Regional Bell Operating Company)
Independent telephone companies created after the break-up of AT&T.

RC4 (Rivest Cipher 4)
Streaming cipher adds pseudorandom number generator bit by bit to sequential bits of digitized plain text.

RIP (Routing Information Protocol)
Routing protocol used to distribute the addresses of reachable networks and metrics.

RO (Receive Only)
Printer terminal without a keyboard for data entry.

RPC (Remote Procedure Call)
Distribute programs between computer systems interconnected with a network without need for in-depth knowledge of diverse networks.

RSVP (Reservation Resource Protocol)
Protocol that enables applications to reserve resources along a route from source to destination.

RTCP (Real-Time Control Protocol)
Protocol providing status feedback from senders to receivers.

RTP (Real-Time Transport Protocol)
Internet protocol for transmitting real-time data such as audio and video.

RTSP (Real-Time Streaming Protocol)
Protocol that runs on IP multicasting.

S/S (Start/Stop) Signaling
Asynchronous communication transfers data preceded by a start signal and concluding with a stop element.

SCP (Service Control Point)
Centralized node that contains service logic to manage call.

SDH (Synchronous Digital Hierarchy)
Standard for digital broadband communications.

SDLC (Synchronous Data Link Control)
Protocol associated with SNA providing efficient full-duplex transmission.

SDSL (Symmetrical or Single-Line DSL)
Symmetrical service with maximum loop of 18,000 feet  in multiples of 64Kbps, up to a maximum of 2Mbps in each direction.

SHA-1 (Secure Hash Algorithm-1)
Message authentication mechanism that hashes a file of arbitrary length into a 160-bit value for heightened security.

SHF (Super-High Frequency)
3GHz to 30GHz frequency.

SIP (Session Initiation Protocol)
Protocol for creating, modifying, and terminating sessions with one or more participants.

SLA (Service Level Agreement)
Contract between an ASP and the end user that stipulates committing to a specific level of service.

SLIP (Serial Line Internet Protocol)
Protocol that provides basic IP encapsulation over dedicated or dialup asynchronous lines.

SMDS (Switched Multimegabit Data Service)
High-speed, packet-switched, datagram-based WAN networking technology offered by some telephone carriers.

SMP (Simple Management Protocol)
Minimal memory extension that includes security features, bulk retrieval, manager-to-manager communication, improved definition of managed objects and error handling, plus exception reporting.

SMTP (Simple Mail Transfer Protocol)
Internet and other UNIX-based network systems used to exchange electronic messages.

SNA (Systems Network Architecture)
IBM’s standardized relationship between its VTAM and the NCP that specifies how products connect and communicate with one another in a network.

SNMP (Simple Network Management Protocol)
Protocol that is used to monitor and manage nodes on a network.

SNMPv2 (Simple Network Management Protocol version 2)
Revised SNMP with additional security features can transfer a large chunk of data at once.

SNR (Signal-To-Noise Ratio)
As the signal in decibels (dB) decreases, it is increasingly difficult to distinguish between information and interference.

SONET (Synchronous Optical Network)
Defines a line rate hierarchy and frame formats for use with high-speed optical-fiber transmission systems.

SP (Service Provider)
Providers of different types of services.

SPE (Synchronous Payload Envelope)
Payload of an STS or STM frame.

SPX (Sequenced Packet Exchange)
NetWare communications used for interprocess communications guaranteeing that a message is received intact and in one piece.

SS7 (Signaling System 7)
Protocol to offload PSTN data traffic congestion onto a wireless or wireline digital broadband network.

SSP (Service-Switching Point)
Switch that originates or terminates a call.

STM (Synchronous Transmission Module)
9 rows of 270 bytes each.

STP (Service Transfer Point)
Switch to translate the SS7 messages and then route them to appropriate network nodes and databases.

STP (Shielded Twisted-Pair)
Two insulated wires in a cable wrapped with metallic casing to prevent interference and to provide noise-free transmission.

STS (Synchronous Transport Signal)
Basic signaling rate for a SONET transmission medium is STS-1, 51.8 million bits per second.

SVC (Switched Virtual Circuit)
Virtual connection on a call-by-call basis.

Synchronous TDM (Time Division Multiplexing)
Time slots on a shared transmission line assigned on a permanent basis.

TA (Terminal Adapter)
Protocol converter that connects a non-ISDN device to the network.

TACS (Total Access Communications System)
Analog telephony used in Europe before GSM became popularized.

TASI (Time-Assignment Speech Interpolation)
Specialized switching that connects a party to an idle circuit based on speech or silence, allowing dual use of same circuit and improving efficiencies up to 80%.

Tbps (Terabits Per Second)
Trillions of bits/second.

TCAP (Transaction Capabilities Applications Part)
Exchange of noncircuit-related information between network nodes.

TCP/IP (Transmission Control Protocol/Internet Protocol)
Packets of data are delivered in sequence in which they were transmitted which is reliable.

TDD (Time Division Duplexing)
Each end of the conversation uses the same frequency.

TDM (Time Division Multiplexing)
Multi channel are divided into time slots and on the receiving end, each time-separated channel is reassembled.

ThickNet (Thick Ethernet cable)
Coaxial cable with electrical characteristics that enable a signal to be carried as far as 1,640 feet.

ThinNet (Thin Ethernet cable)
Coaxial cable with electrical characteristics that enable a signal to be carried as far as 607 feet.

UBR (Unspecified Bit Rate)
ATM service class with no service guarantee used for noncritical information transfer.

UDP (User Datagram Protocol)
Minimal-functionality protocol.

UNII (Unlicensed National Information Infrastructure)
Unlicensed radio bands operating at 5.2GHz.

UNIX
A multiuser, open operating system by Bell Laboratories.

UPS (uninterruptible power supply)
A device that draws power from batteries as a back up with an auxiliary generator.

UPT (Universal Personal Telephony)
Personal mobility across many different kinds of fixed and mobile networks.

UTP (Unshielded Twisted-Pair cable)
Two insulated wires in twisted pair cable that are not insulated.

VAD (Voice Activity Detection)
Removal of silent periods and redundant information.

VAN (Value-Added Network)
Telecommunication services provided over public or private networks accompanied with computerized intelligence like reservation systems, bulletin boards, information services.

VAR (Value-Added Reseller)
Vendor offering distribution and sales.

VBR (Variable Bit Rate)
VBR service for typically bursty networks on LAN to LAN interconnection designed for real-time voice and videoconferencing applications and mission-critical data applications.

VC (Virtual Circuit)
The logical connection of a packet network.

VC (Virtual Container)
Data structure designed for the transport and switching of sub-STM-0 network services.

VCI (Virtual Channel Identifier)
Part of a cell header that identifies the channel associated with the cell.

VDSL (Very-High-Bit-Rate DSL)
Transmission medium that provides a maximum span of about 5,000 feet (1,500 meters) over a single twisted-pair cable.

VF (Voice Frequency)
Audio frequency range is 250Hz to 3,400Hz, the same as telephone frequency.

VHF (Very High Frequency)
Frequencies between about 30MHz and 300MHz is the operating band for radio and television channels.

VISP (Virtual Internet Service Provider)
A branded ISP offering turnkey products.

VLAN (Virtual Local Area Network)
Networked computers behave as if they are connected to the same wire even though they may actually be physically located on different segments of a LAN.

VLF (Very Low Frequency)
Frequency below 30KHz.

VoATM (Voice over ATM)
Transporting integrated digital voice, video, and data over ATM networks.

vocoders (voice coder/decoder)
High-bit-rate vocoder devices are used by PCS, wireless local loops, and wireless office telecommunication systems applications. Low-bit-rate vocoders are used in cellular systems.

VoDSL (Voice over DSL)
Delivery of voice transmissions over DSL lines.

VoFR (Voice over Frame Relay)
Transporting integrated digital voice, video, and data over Frame Relay networks.

VoIP (Voice over IP)
Technology for transporting integrated digital voice, video, and data over IP networks.

VP (Virtual Path)
Term for a collection of virtual channels with the same endpoint.

VPI (Virtual Path Identifier)
Portion of a cell header that identifies the virtual path to which the cell belongs.

VPN (Virtual Private Network)
Software-defined network offered for voice and data communications among multiple sites.

VR (Virtual Reality)
Computer-based  sensory environment dynamically controlled by the individual so that the environment appears real.

VRC (Vertical Redundancy Check)
Error-checking method uses a parity bit for each character.

VSAT (Very-Small-Aperture Terminal)
Earth station with a small antenna.

VT (Virtual Tributary)
Transport and switching of sub-STS-1 network services.

WAN (Wide Area Network)
Computer networks connected over long distances, often by telephone lines and satellite transmission.

WAP (Wireless Application Protocol)
Transforming Internet info to display it on the small screen of a mobile telephone or other portable device.

WARC (World Administrative Radio Conference)
Global authorities charged with determining spectrum allocation.

WDM (Wavelength Division Multiplexing)
Transmitting signals at different wavelengths through the same fiber.

WML (Wireless Markup Language )
Markup language used in the WAP environment.

WWW (World Wide Web)
Internet application using hypertext links to access and display multimedia information.