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On some PBX systems the digital phones have access to features by pressing a Feature button or by pressing a flash key and then entering the same access code as used by analog phones.. A

Worldwide Training

Standard Telephony Features

Glossary

Introduction to Document

This document contains a glossary of the features and terminology of standard telephony

Objective

Upon completion of this unit you should be able to:

Identify and describe the features of standard telephony

A

ACD Automatic Call Distribution – there are many different models for ACD

Low-end ACD is minimal queuing capability for a station or group of stations with little or

no reporting/monitoring Low to Mid-level ACD will usually include more detailed reports and other ACD features such as Silent Monitor, overflow queuing and messaging High-end ACD will generally include features like Skills based routing, Time-of-day routing, Agent-Supervisor communications, elaborate/customizable report capabilities, CTI interfaces for database lookups, IVR integration In addition there is usually support for large numbers of agents and Supervisors have extensive monitoring, management and reporting capabilities

ADPCM - Adaptive Differential Pulse Code Modulation An encoding technique,

standardized by the CCITT, that allows a 4kHz voice channel to be carried within a 32Kb/s digital channel The technique uses 3 or 4 bits to describe the difference between two samples, taken at a sampling rate of 8,000 times a second

A-Law - A companding algorithm used as the CEPT standard for DS-0 PCM speech

companding (See Mµ-Law)

AMI Alternate Mark Inversion is a T1 line coding method This is the older of the

two commonly available See Line Coding – T1 See Also B8ZS

Amplifier is an electronic device that strengthens a signal

Amplitude is the high point of the wave in an analog signal

Analog Telephones sometimes referred to as 2500 Sets Analog phones usually

interface to analog station cards in the PBX In some PBX’s the analog station can access PBX features through the use of Feature Access Codes For example; Flash * 6 might be used to signal to the PBX that the analog station wishes to transfer the call it

is currently in progress with Other codes can identify Conference, Pickup, Park and

so on More advanced analog sets might have buttons that can be configured to send the codes ‘automatically’ thus simplifying the user interface On some PBX systems the digital phones have access to features by pressing a Feature button or by pressing

a flash key and then entering the same access code as used by analog phones (See also Flash and Digital Telephones)

ANI (See Automatic Number Identification)

Attendant Console a multi-line phone (physical or softphone) that can access

incoming or outgoing trunks to route calls to subscribers PBX manufacturers generally list several Attendant Console features such as Attendant Recall, Attendant Hold, Attendant login and so on…

Auto Answer If this feature is programmed on the template, it will cause the phone to

go off-hook (speakerphone) automatically when an incoming call is received

Auto Attendant is a device that answers callers with a digital recording, and allows

callers to route themselves to an extension through touch-tone input in response to a voice prompt

Automatic Callback allows internal users who placed a call to a busy or unanswered

internal telephone to be called back automatically when the called telephone becomes available When a user activates automatic callback, the system monitors the called telephone When the called telephone becomes available to receive a call, the system originates the automatic callback call The originating party receives priority ringing The calling party then lifts the handset and the called party receives the same ringing provided on the original call

Automatic Call Distribution is provided through groups of employees who serve

customers using telephone, facsimile, Email, the Internet, or remote video links to provide more convenient sales, service or billing operations When managed well, these centers can serve customers quickly, efficiently and cost-effectively Center products allow customers in an enterprise to:

1 Retain its customer base through fast and efficient customer response

2 Cater to the needs and preferences of its various customer segments

3 Offer its customers new ways of transacting business

Automatic Camp On is the ability to camp on to a busy station or circuit without the

requirement to invoke a feature access code On some systems this was allowed from either/both internal and external callers For example a user calls a DID number and hears a standard busy signal if the caller does not hang up within a predefined time period the system would generate a camp on tone and the call is effectively held for that station until the phone becomes available This could be configured such that for internal callers the calling station could hang up and when the called station become available the system would issue a call-back ring to the calling station and ring through to the called station An occasional situation arose where the called station did not become available for so long that the caller forgot they were camped on and would ‘answer’ the phone as if it were a new call coming to them

Automatic Number Identification ANI is the ability to send/receive the calling

number Some systems can route calls based on this information by making a match in

a database and following predefined routing rules (See also DNIS)

Automatic Route Selection ARS - Automatic Route Selection (ARS) simplifies local

and long distance dialing by automatically selecting the most convenient and effective route and by inserting and/or deleting the proper routing digits

cost-Authorization Code May be referred to as Checked/Verified,

Un-Checked/Un-Verified, Forced, Variable and other descriptions This code may be used to

1 control access to features

2 identify user for charge-back purposes

3 prohibit or limit access to external trunks or facilities

4 support input of user defined codes; wrap-up codes for ACD, client/matter codes for law firms and so on The codes are stored in the CDR/SMDR database and used to track reason for calls or bill back to clients

B

B8ZS - Bipolar 8 Zero Substitution is a technique used with DS-1 signals in order

to maintain ones density, where a special code is substituted for eight consecutive zeros and marked by two bipolar violations The use of B8ZS allows the use of a full 64kb/s DS-0 for data transmission This is called ‘clear channel’ Not compatible with older "AMI" equipment (Referred to Bipolar 8 Zero Substitution by early AT&T ref.) The receiver must have the ability to recognize the code and return it to the same bit sequence (8 zero’s) Applied against all 24 DS-Os on a DS-1, the effective data throughput of the DS-1 facility is increased with B8ZS from 1.344 Mbps to 1.536 Mbps, a 14% increase in throughput

Bandwidth is a measure of the communication capacity or data transmission rate of a

Circuit The total frequency spectrum (in Hertz - cycles per second) that is allocated

or available to a channel, or the amount of data that can be carried (in bits per second)

by a channel

Basic Rate Interface (BRI) is an ISDN offering that allows two 64kbps and one

16kbps channels to be carried over 1 typical single pair of copper wires This is the type of service that would be used to connect a small branch or home office to a remote network Through the use of BONDING (Bandwidth on Demand) the two 64kbps channels can be combined to create more bandwidth as it becomes necessary

B Channel Bearer Channel Is one of the multiple user channels on an ISDN circuit

Used to carry user's voice/data

Bell Labs is the basic research facility that was AT&T's primary research facility Bell Labs was spun off with Lucent Technologies Many very important discoveries have been made at Bell Labs including the transistor, communications theory, and radio astronomy

Bellcore BELL COmmunications REsearch See Telcordia The research and

development organization owned by the RBOCs Bellcore represents the RBOCs in developing standards for Telco equipment and in testing equipment compliance to those standards Bellcore also offers educational and training programs open to all interested parties

BLF (See Busy Lamp Field)

Blockage is a percentage of calls that do not complete due to lack of resources such as

an incoming call to a PBX that cannot be completed because there are no trunk circuits available to transport the call to the PBX or the percentage of devices that will not get service when simultaneous resources requests exceed system resource (such as time slots or tone senders) availability (See Traffic and Erlang)

Blocking/Non-Blocking are terms used to describe the ability to provide resources to

all configured devices simultaneously A Non-Blocking switch can provide a time-slot

or transmission path to all devices simultaneously A Blocking system cannot Most PBX systems are Blocking in their standard configuration but with additional resources or specific methods of allocating ports many of them can achieve a Non-Blocking state This is usually an expensive proposition and may be a competitive advantage for true non-blocking systems

Bridged Call Appearance allows single -line and multi appearance telephone users to

have an appearance of another user’s primary extension number The bridged call appearance can be used to originate, answer, and bridge onto calls to or from the other user’s primary extension number

Busy Lamp Field is an indicator that a station is in use (See also DSS) In some

systems this is a physical or software module that attaches to a phone, Attendant Console or softphone and can be used to monitor several or hundreds of

extensions/directory numbers for state Some examples of ‘state’ may be:

Bypass is equipment or circuits that allows incoming trunk circuits to be bridged

directly to specific telephones in the event of a catastrophic system failure Some PBXs had an optional Bypass capability that could be added directly to the system while others used 3rd party equipment to provide the same capability Analog Bypass

is the most common type but there are Bypass units that can cross-connect/bridge incoming T1/Analog circuits to digital/analog phones

Buzz – Manager/Secretary feature that lets the manager to buzz the secretary to come

into the office or the Secretary can buzz the Manager alert them to a call or visitor

C

Call Blocking is controlled through the end-users class of service If the end-user has

not been given access to a specific trunk group or trunk the call will be blocked

Call Coverage provides automatic redirection of calls to alternate answering

positions in a Call Coverage path Call Coverage allows you to:

1 Establish coverage paths with alternate answering positions

2 Establish redirection criteria that govern when a call redirects

3 Redirect calls to a local switch location

4 Redirect calls to a location on another switch

5 Redirect calls to a remote location

6 Redirect calls based on time-of-day This allows users to change back and forth between two coverage choices (either specific lead coverage paths or time-of-day tables) Users may make these changes either an on- or off-site location

Call Detail Recording CDR collects detailed information about all incoming and

outgoing calls on specified trunk groups and, if you use intraswitch call detail records, about calls between designated extensions on the switch It sends this information to a printer or other call detail records output device that may also provide reports You can use this information to compute call costs, allocate charges, analyze calling patterns, detect unauthorized calls, and keep track of unnecessary calls (See also SMDR)

Call Duration is the period of time that begins with Answer Supervision (destination

off hook) and ends when the call is terminated

Call Forwarding allows users to redirect calls to designated destinations The

forwarded-to destination can be an internal extension, external (off-net) number, an attendant group, or a specific attendant Call Forwarding provides five functions:

Call Forwarding-All Calls, Ring-no-answer, Busy — Allows a user to redirect

incoming call to the forwarded-to destination

Call Forward Busy/Don’t Answer — Allows a user to redirect incoming calls to a

forwarded-to destination only when the user is busy or when the call is not answered after an administrable interval If the extension is busy, the call forwards

immediately If the extension is not busy, the incoming call rings the called extension, then forwards only if it remains unanswered longer than the administered interval

Call Forwarding Off Net/External — Allows a user to forward calls to an off-net

Call Forwarding Override allows the user at the forwarded-to extension to override Call Forwarding at the forwarded-from extension on a per-call basis so the user can initiate a call or transfer a call back to the forwarded-from extension

Call Hold allows telephone users to disconnect from a call temporarily, use the

telephone for other call purposes, and then return to the original call

Called Party Address This is the destination phone number of a call delivered to a switch

For instance this could be the CLID (Calling Line ID) of a call delivered to a PBX using DID

or two-way trunks (See also DID)

Calling-party-ID Interface to the PSTN is provided through a digital gateway

supporting ISDN Primary Rate Interface The digital gateway must support ISDN Primary Rate Interface from the network to receive this feature On an inbound call the network passes the telephone number to the gateway The gateway then passes the information to the IP telephony server where the information is passed on to the telephone instruments and reports such as call detail records

Call Park allows users to put a call on hold in an ‘orbit’ (an orbit is something like a

phantom extension) and then retrieve the call from any other voice terminal within the system by dialing the orbit number This is commonly used in an

Attendant/Subscriber scenario

On some systems the call was actually parked on a idle/busy extension If it was parked to a busy extension the busy subscriber would hear an audible beep tone indicating a call had been parked on their extension The party they were talking to would not hear the beep This feature is commonly used in a Boss/Secretary scenario

In each scenario if the call is not picked up in a reasonable time the call should ring back to the attendant or the party that placed the call in park With the advent of voicemail the Call Park feature is not as commonly used

Call Pickup allows a user to answer calls that alert at other extension numbers within

the user’s specified call pickup group

Call Pickup – Directed allows subscriber to press a key/ dial a code and then an

extension number to pickup a ringing call at a specific station

Call Pickup – Group allows user to enter a code and pickup any ringing phone

configured in the same group

Call Quality is a measure of the expected quality as determined by the MOS of the

Codec (with or without voice activity detection), and the delay, jitter, and congestion

on the network

Call Waiting/ Retrieve allows a call to overflow to a second line on an end-users

telephone When the call arrives the end-user will have both a visual and audible notification The end-user places the first caller on hold and depresses the second line

to retrieve the call

Calling Party Name Display feature provides internal station users with an enhanced

visual aid in making and receiving calls In addition to the calling or called party’s

extension number, a customer-definable identification (typically the party’s name) also appears on a stations LCD display

Calling Party Number Display feature provides internal station users with a visual

display of the internal and external numbers terminating to their station set The external number appears only when the local provider passes the information through the PSTN network

Camp On feature allows callers to wait for a busy station or trunk to become

available Typically caller will hear a tone identified as camp-on May require caller

to stay in off-hook condition or may support automatic callback Some systems support this from both internal and external callers System may require input of an access code when reaching a busy station or be set to automatically camp-on Some phone systems will not allow camp-on to phones with voicemail configured as the forwarding target

CAS Centralized Attendant Service – allows a centralized group of attendants to

answer calls across the network and transfer them back to stations without holding up the private network links (Sometimes call release-link trunks)

CCITT - Consultant Committee on International Telephone and Telegraph

An international organization that develops standards and defines interfaces for telecommunications (Now known as ITU International Telecommunications Union)

CCS is an Acronym that may identify different functions:

1 Common Channel Signaling (out of band signaling such as occurs with ISDN) Many PBXs proprietary private network link either use an actual PRI interface or simulate a D-channel on standard DS-1 circuits

2 Centum (Roman Numeral C = One Hundred) Call Seconds - standard unit of traffic, used in communications engineering Typically the CCS associated with common station traffic is 7 to 12 CCS This number is an assumption when calculating traffic when the actual traffic per station is unknown (See also Erlang)

Cell can be identified by a couple of definitions:

1 Packet switching information grouped in units of uniform size Cells are fixed-length packets (e.g ATM 53-byte cells)

2 A small group acting as a unit in a larger organization (e.g one of the separate geographical areas covered by a radio transceiver antenna in a multi-antenna cellular phone system, a spreadsheet cell, a biological cell, etc.)

Central Office is a location that houses a telephone system generally used for Public

Network interfaces such as links between Central Offices, Business Circuits (Trunks) and home telephone lines Provides phone service to subscribers within a specific geographical area

Central Processing Unit is the part of the switch containing the logic, computation

and control circuits

Centrex – public CO offering that provides business telephone services similar to a

PBX Subscribers can dial by directory number, have voicemail and other business features/applications in a limited fashion compared to a PBX Usually managed by the LEC and includes long term contracts

Centrex Flash – allows subscriber to issue a command that will in turn cause a flash

to be sent to the Centrex system to perform transfers and other features

Channel or Time Slot is a single, bi-directional, direct connection between two TDM

devices An actual path you can talk or send data over.

Circuit is a physical path through which electrical signals can pass It consists of a network of

conductors and other components, separated by insulators Technically this term cannot be applied to fiber optic or other "non-metallic" paths.

Circuit Switching A system where a dedicated channel is allocated to the users of that call

for the duration of that call That channel is allocated for the duration of the call regardless if information is being transmitted at any given moment Bandwidth through the channel is fixed,

at no time may this bandwidth be exceeded If this bandwidth is not used it is wasted While inherently inefficient, the dependable and reliable nature of circuit switching makes it ideally suited to real-time voice and audio/video conferencing applications This is in stark contrast to systems where statistical multiplexing is used (See Statistical Multiplexing)

Class 3 - IEC - Interexchange Carrier

Hierarchical interconnection for Class 4 and optional Class 5 Switches

Class 4 - Tandem Office - Toll Office

Interconnection for Class 5 Switches and long distance via Class 3 IECs Optional direct connection to higher volume Class 4 sites A Class 4 may also serve as a Class

5 CO

Class 5 - Central Office -End Office

Connection to local Customer Premise Equipment and local switching Capacity typically is up to 100,000 lines, 1 to 10 NXX

Class of Service - COS

In some PBX systems the COS is used to group telephones and resources, control access to facilities and provide limitations on what numbers can or cannot be called It can also be used to control access features that can or cannot be accessed For example; An Executive telephone with COS 10 might be allowed to call long distance without entering an account code but a lobby phone with COS 3 might be required to enter an account code even to dial local numbers Any other phones assigned COS 10 would have the same restrictions and limitations as the Executive telephone COS could also be used to perform call blocking so that if blocking was setup between COS 3 to COS 10 then any phones assigned to COS 3 could not call phones/trunks with COS 10 but COS 10 could still call COS 3 This is an example of a patient room phone (COS 3) being blocked from calling the Doctor’s phone (COS 10) but the Doctor could still call the patient room In Cisco Call Manager system these functions can be performed with Partitions and Calling Search Space

CLEC Competitive Local Exchange Carrier This is your local telephone service

provider who is one of the new-generation providers rather than a RBOC or

Independent A CLEC is really just an Independent albeit one formed after the

divestiture of AT&T (See LEC)

CLID Calling Line Identification This is the ISDN and SS7 equivalent of Caller

ID; I.E the number of the calling party (See also ANI)

CO Central Office The Telco facility where your local telephone circuit leads to

Contains Switches and Trunks as well as the local telephone circuits

CPE Customer Premise Equipment- Customer owned equipment located at his/her

facility In the USA and Canada the NT1 is part of the CPE

Conference – allows 3 or more callers to join in a single conversation Conference Add/Drop – add or remove callers from conference cRTP -Compressed RTP or RTP Header Compression, is a method for making the

VoIP packet headers smaller to regain some of the "lost" bandwidth cRTP takes the 40-byte IP/UDP/RTP header on a VoIP packet and compresses it to 2-4 bytes per packet, yielding approximately 11.2K of bandwidth for a G.729 encoded call with cRTP (See RTP)

CSU/DSU is a device that incorporates the functions of a CSU (Channel Service Unit)

and a DSU (Data Service Unit) This device is typically a CPE device used to separate the customer environment from the carrier environment Various CSU/DSU units have the ability to support different line code formats, reports, troubleshooting tools and features

CODEC is a term combining COder and DECoder The coder portion receives

analog signals such as a speakers voice and converts it into a digital representation of the analog signal for example PCM At the receiver side the decoder portion translates the digital signal back into an analog voice signal for the end user CODEC can also

be used to perform compression

Com Group – includes a group of stations that can override features such as

do-not-disturb by dialing a com group index number

Computer Telephony Integration - CTI

The integration of telephony function with computer applications

Conference is a single connection combining more than 2 parties into a conversation

Most PBX systems state a maximum number of parties and further qualify it with how many can be external to the system PBX manufacturers usually set a limit to the total number of attendees and simultaneous conferences Some PBX manufacturers offer

an optional enhanced conference bridge capability by adding conferencing cards or adjunct systems to provide for increased capacity of both attendees and simultaneous conferences

Conference Bridge (or MCU) is a device that is used to blend the audio signal from

more than 2 callers into a single conversation

Country Code

Two or three digit codes used for International calls outside of the North American Numbering Plan area codes Dial: 011 + country code + city code + local phone number) (e.g "011 + 91 + 22 + 123- 4567" 91 = India , 22 = Bombay)

CSU/DSU is a device that incorporates the functions of a CSU (Channel Service Unit)

and a DSU (Data Service Unit) This device is typically a CPE device used to separate the customer environment from the carrier environment Various CSU/DSU units have the ability to support different line code formats, reports, troubleshooting tools and features

D

D-4 (or Super Frame SF)

A data transmission format comprised of 12 frames of 192 bits each A single 193rd bit is used for link control and error checking As an industry standard, D4, also known as SF, has been superseded by the Extended Super Frame (ESF) format However because ESF is not backward compatible and there continues to be a large installed base of channel banks and DS-1 Multiplexers that are based upon D4, it is still the default private line formatting technique

D-4 Channel Bank

A multiplexer used to convert 24 voice grade analog or data channels into a DS-1 The D-4 is not equipped for software-controlled provisioning or remote circuit testing

DACS - Digital Access Cross-Connect System is a digital switching facility

interconnection device A DACS allows reconfiguration of lower levels of capacity within a circuit without the need for manual changes in the interconnections A DACS

is similar to a MUX, but a DACS permits software changes that would require physical changes with a MUX

D Channel - Data Channel or Delta Channel (depending on who you ask) The

channel that handles ISDN network related data between the user's equipment and the Telco switch Used to carry data to set up calls and receive calls Some Telco's also allow users to use the D channel to access the packet data network, with appropriate terminal equipment

Dialed Number Identification Service – DNIS is an optional feature DNIS delivers

identifying digits (up to 14 digits) that distinguish incoming calls This allows CPE to identify which number was dialed when multiple numbers terminate on the same trunk group and offers the ability to route calls based on the dialed number (See also ANI)

Decibel - Db - db

A unit of power (sound, electrical or optical) increase (amplification) or loss (attenuation) that is proportional to the exponential increase or decrease in power

Demarcation Point - Demarc

A point (such as a jack or cross-connect panel) at which ownership or responsibility for operating and maintaining facilities passes from one party to another

Dial Tone

Start Dial/Ready To Place/Originate A Call When the off hook indication is received

at a central office, a dial tone signal is sent to the originating caller on a switched network to indicate that the switch is ready to accept a number

DID Intercept accommodates an FCC requirement that calls to non-working DIDs or

unused DIDs within a purchased block be routed to a recorded announcement notifying the caller they have read a non-working DID Generally this was preferred since it did not provide answer-supervision An alternative to the recorder was routing the caller to a human although in most systems that would provide answer-

supervision and begin the billing process Voicemail was not considered a suitable recorder interface since it generally provides answer-supervision as soon as it connects

Digital

A device or method that uses discrete variations in voltage, frequency, amplitude, location, etc to encode, process, or carry binary (zero or one) signals for sound, video, computer data or other information For example, a digital clock displays the time as discrete numeric values, rather than angular displacement of analog hands Digital communications technology generally permits higher speeds of transmission with a lower error rate than can be achieved with analog technology When analog signals are received and amplified at each repeater station, any noise is also amplified

A digital signal, however, is detected and regenerated (not amplified) Unlike amplification, any noise (less than a valid signal) is eliminated by digital regeneration

Digital European Cordless Telecommunications

A wireless standard for communications, operating at 1,88-1,9 GHz The system is developed for high traffic rates and small cells Applications are private, residential and business telephone and data transmissions

Digital Phones sometimes called Feature Sets are usually proprietary devices built by

the PBX manufacturer or built to their proprietary specifications Typically connected

to cards in the PBX specifically designed to interface to these phones Digital phones are generally much more expensive (and feature rich) than analog phones Some manufactures require cards and phones both to be upgraded or changed when expanding system capacity or enhancing software Digital phones usually had some number of line/feature keys If the phone has more than one line it is called a “multi-line” set Some phones have displays, speakers, interface(s) for special adapters (such

as data ports, BRI or analog extenders), DSS/BLF modules and key expansion modules In addition some manufacturers require specific Digital Phones to be used for certain functions such as ACD If a non-ACD designated set is used the manufacturer will provide little or no support for the customer Many manufacturers proprietary voicemail system will use the digital ports to integrate to the system Since this is a proprietary interface it makes it very difficult for competitive equipment to attain a comparable level of integration

Direct Inward Dialing (DID) trunk group allows an incoming call from the exchange

network to reach a specific extension number directly without attendant intervention

In North America DID blocks are purchased in groups of 10, 20, 100 or larger

Direct Inward System Access - DISA is the ability to access a PBX from an outside

telephone number For example, a caller might dial an assigned number, input a security code and then use the PBX to place a long distance call

Direct outward dial trunk group allows the station end-user to call outbound by

dialing an access code or by depressing a pre-defined feature key with the trunk appearance on it The class of service assigned to their station determines the end-users outbound dialing privileges The class of service may be temporarily upgraded

by use of an authorization code

Direct Page – allows paging directly through a station’s speakerphone

Direct Trunk Select – lets a technician bypass routing tables to test specific trunks or

circuits

DISA – (See Direct Inward System Access) Distribution Group - distributes calls more evenly than standard hunt groups If the

first call goes to station A the next call will go to station B even if A is available

Disconnect - Call termination and the information associated with it such as time of

day, who disconnected (originator, destination, etc.)

Distinctive Ringing provides several ringing cycles to help telephone users and

attendants distinguish between incoming call types

DN Directory Number is a phone number used within the PBX Length may

typically be anywhere from 2 to 10 digits with 3 or 4 digits as the most common

DNIS (See Dialed Number Identification Service)

Do Not Disturb allows guests, attendants, and authorized front-desk telephone users

request that no calls, other than priority calls, terminate at a particular extension until

a specified time At the specified time, the system automatically deactivates the feature and allows calls to terminate normally at the extension

Drop/Insert (Add/Drop) is the ability to separate portions of a DS-1 so that it can

transport different types of information or terminate different traffic types on a single transport medium For example an Add/Drop CSU might be used to share a T1 for both voice and data If a voice application requires 10 channels and the remainder might be used to transport data This is most commonly used between sites on a Point-to-Point T1/E1 but could also be used with an ISP/Carrier to transport both PCM phone calls and data to the cloud where the voice would be carried by the PSTN and the data would be redirected to the ISP service

DS-0 Digital Signal, level 0 is 64 kilobits It is equal to one voice

conversation/channel digitized under PCM (See DS-1 also)

DS-1 Digital Signal level 1 is 1544 kilobits (1.544 megabits), which is twenty-four

64k, channels plus framing bits (24 x 64,000 = 1536000 bits/sec + 8000 frame bits

=1544000 bits or 1536kb or 1.544mb)

DSS Direct Station Select is similar in function to BLF (see Busy Lamp Field) DTMF, Dual-Tone Multi-Frequency, is the ITU and Bellcore signaling standard for

telephone handset push-button keypads The keypad is a 4x4 matrix of frequencies each button corresponding to two frequencies Not only has DTMF become important for rapid dialing, but has also taken on an added dimension of providing voice mail as well as other menu driven options during connected calls DTMF specifications are: Each digit corresponds to 2 frequencies:

• Dynamic Range - 25 dB

• Twist - 8 dB

• SNR - 30 dB

• Minimum Recognition - 40 msec

• Maximum Rejection - 27 msec

• False Alarm - 0 (30 min Mitel Test Tape)

Digit

Row Frequency (Hertz)

Column Frequency (Hertz)

Return Code

# 941 1477 0x1B

E

E1 is the European digital transport medium equivalent to North American T1 E1

carries information at the rate of 2.048 million bits as opposed to T1 at 1544 million bits per second E1 uses 30 channels for carrying voice or data and 2 channels for signaling and control A common term used to describe E1 is “30+2” When used as the underlying media for ISDN PRI, one of the control and signaling channels is used

as the D channel while the 30 voice and data channels are used for B-channels

E-9-1-1 – Enhanced 911 Echo Cancellation

A technique used with voice circuits to isolate and filter unwanted signal energy that accompanies analog transmissions

Echo Canceller

A circuit feature that turns off the incoming signal while one end of the call is talking (to avoid an annoying long distance echo) It must be disabled for Full Duplex (simultaneous 2-way calls) An echo canceller does not turn off the voice channel, as stated, but electronically removes unwanted echo, while maintaining a full-duplex channel An echo suppressor disables the channel in one direction or the other, depending on who is talking Echo cancellers must be disabled for some types of high-speed modems calls, and must also be disabled for "cle ar channel" data calls, such as ISDN

Erlang - Traffic Unit - (1 Erlang = 3600 Calling Seconds = 36 CCS)

An international unit of average traffic on a facility during a period of time (usually a busy hour) The number of erlangs is the ratio of the time the facility is occupied (continuously or cumulatively) to the time the facility is available

Error-free Seconds

A measure of the quality of the signal being transmitted It is a percentage representing the total amount of time over a 24-hour period that the signal contained bit errors and it is calculated using a test pattern defined in CCITT Recommendation 0.151

ESF - Extended Super Frame

An enhanced version of D4 formatting, and it is the current industry standard ESF is composed of 24 frames of 192 bits each ESF provides 16 signaling states in the 193rd bit to ensure synchronization, supervisory control, and maintenance capabilities

Executive Busy Override allows a user to enter into an established connection A

warning tone notifies the talking parties that a third party is about to enter the conversation The executive override feature can be issued after a user has dialed a

busy extension This feature requires a special class of service

F

Facility – is commonly used in the PBX environment to refer trunks but can be a

generic term for a logical component of a system (such as a telecommunications

channel, a switch, a computer, groups, a control center, a building, etc.)

Facility Busy Indication provides multi appearance telephone users with a visual

indication of the busy or idle status of one of the following system resources:

FCC - Federal Communications Commission

US regulatory body that regulates interstate communications: licenses, rates, tariffs, standards, limitations, etc Appointed by U.S President

Feature Access Codes are combinations of signals and DTMF tones invoked by a

user to perform features such as conference, transfer, pickup, park and so on (See Analog Phones, Digital Phones and Flash)

Flash is a term describing a signal sent to the PBX indicating that the subscriber

wishes to perform a feature Originally pressing the hook-switch button(s) on an analog phone performed a flash by temporarily opening the circuit and interrupting the current flow (Note: in some countries Flash is called Ground Flash because the signal is temporarily taken to ground instead of opening the circuit) Parameters within the Telephone System identified the length of time required to recognize the interruption as a flash If the hook-switch wasn’t held long enough (low-flash parameter) the system ignored interruption If the hook-switch were held too long (high-flash parameter) the call would be disconnected since the system recognized it

as an On Hook signal Newer analog phones and some digital phones had buttons that would automatically send a flash signal In some cases the Low and High Flash System Parameters would need to be adjusted to accommodate the hard-coded flash sent by the phone

Foreign Exchange (FX)

A DS-0 line utilizes Feature Group A facilities on one end of the circuit The Feature

Group A service connects a customer premise in the foreign location with the line side

of a BOC central office switch in the U.S The customer premise end of the circuit is referred to as the closed end because it terminates on a station instrument, key system,

or PBX The CO switch end of the circuit is referred to as the open-end because it is open to the public switched network The open end of the circuit appears as a local business line in a local exchange, different from (foreign to) the local exchange of the closed end of the circuit A dial tone from the distant city's local office is heard when this line is accessed, and a local phone number can be associated with the FX An FX has fixed monthly charges for the originating local access, IXC, international circuits Usage charges are applied through the local telephone company at the open (US) end The advantages of an FX line are the use of a local phone number for long distance calls and high volume centralized long distance calling at reduced fixed costs In the case of international FX services, the open end must be in the US, unless the foreign PTT can support this service In many countries this service falls under regulatory laws

Fractional T1 - FT1

A service that uses a portion of a 24-channel T1 circuit FT1 allows 64 Kbps increments from 2-channel 128 Kbps through all 24 channels at 1.544 Mbps

Frame Slip (Also called just "slip")

Any shift of the timing on a circuit Usually the difference between D4 Super Frame and Extended Super Frame or an un-framed signal stream During an out-of-frame condition, one frame slip would increment

FX (See Foreign Exchange) FXO Foreign Exchange Office – Usually used to connect loop-start analog Central

Office trunks

FXS Foreign Exchange Subscriber - Usually used to connect end-user devices such

as telephones, modems, fax machines and so on…

G

Glare - On a POTS line an incoming call is signaled by periodically applying an AC ring voltage to the line Since there is a semi random period before the ring, and pauses between rings, it is possible to seize a line which is "about to ring" (and answer

a call) when attempting to place an outgoing call When this scenario happens it is called glare Glare is much less likely if Ground Start trunks are used (See Ground Start Trunk)

GMT

Greenwich (England) Mean Time - Zulu Time GMT is 6 hours later than Central Standard Time (CST in the northern hemisphere Winter) and 5 hours later than Central Daylight-Savings Time (CDT in the northern hemisphere Summer) GMT (Zulu Time) is always the same worldwide Communication network switches are typically coordinated on GMT