Glossary

abort mask

A bit mask parameter used for the play and record functions to indicate which DTMF digits abort the respective function.
addaemon

A background process used to establish a system shared copy of default parameters for AG Access.
ADPCM

Adaptive Differential Pulse Code Modulation; a method for digitizing and compressing speech data.
ADSI

Analog Display Services Interface; a specification for sending display information over ordinary telephone lines.
AG The Alliance Generation product line of telephony and voice processing hardware and software, including highly integrated hardware modules.
AG driver

The hardware device driver that controls all AG boards in a host system.
AGC

Automatic Gain Control; an algorithm applied to incoming speech (recording) before compression and storage so that the amplitude of the stored speech is kept at a target level.
agmon

Utility program which reads a configuration file and uses it to load and monitor the AG hardware.
ASCII

American Standard Code for Information Interchange; the code used for numeric representation of alpha-numeric characters.
asynchronous programming

Enables concurrent processing between AG boards and the host CPU whereby the application initiates telephony functions on the AG board through AG Access and receives events from AG Access.
blind transfer

Call transfer method in which AG Access places a second call and then disconnects its port from the PBX before call placement is resolved.
blocking (inbound calls)

Call control action taken by an application to refuse any further incoming calls. Depending on the protocol, blocking calls will either tell the Central Office or switch not to offer any calls (see reverse-make- busy), or reject every call that is being offered (not answer, or play busy, etc.).
caller ID

A telephone company service for delivering the calling party's number between the first and second incoming ring by means of FSK modem signals.
call progress

A function that allows the application to control call placement. Call progress monitors in- band energy to detect network tones, voice, and other tones such as modems.
CAS

Channel Associated Signaling; telephone line interfaces in which the signaling is delivered separately for each line. This contrasts with Common Channel Signaling, where the signaling for a group of lines is combined in one signaling circuit.
CED

CallED party tone; a 2100 Hz burst transmitted by a fax or modem to synchronize the called and calling parties for negotiation.
cleardown tone

An in-band tone from the CO or switch indicating that the remote party has hung up.
CO Central Office; a connection point for a customer's line to the public telephone network.
CPE

Customer Premise Equipment; equipment connected to telephone company lines that is owned by the customer.
commands

Instructions sent by the application via AG Access to the AG board.
DID

Direct Inward Dialing; an incoming telephone service which delivers the final portion of the called address to the CPE, thus allowing the caller to reach an individual extension of a PBX.
done event

An event sent by AG Access which signifies the completion of an asynchronous function.
DSP

Digital Signal Processor; a special microprocessor that is designed to rapidly perform the calculations required for voice processing.
DTMF

Dual Tone Multi-Frequency; any of the dual tones generated by a 2500-type telephone; also called Touch-Tone ®.
E&M

Ear and Mouth; a telephone signaling system that uses two wires called the E-lead and the M-lead. This name is also applied to the A and B bit signaling used on digital circuits.
echo cancellation

An algorithm for analyzing data output on the line so that it can be removed from the received signal.
encoding (speech)

Any of the compression techniques for digitizing and compressing speech data.
energy detector

An algorithm for reporting the existence and non-existence of signals and audio on a telephone line based on a set of qualifying parameters; examines the in-band signal to distinguish between silence and energy.
events

AG Access data structures that contain notification of certain conditions or state changes sent from the AG board to the application program via AG Access. All events are represented as an ADI_EVENT `C' data structure. The structure informs the application what event occurred on which port, and provides ancillary information specific to the event. An indication that playing a message is done is a typical event.
FIFO

"First In, First Out"; name given to a queue wherein entries (events, in the AG Access case) are processed in the order they were received.
frames (speech)

The smallest set of samples (sometimes including optional headers or trailers) that a speech compression algorithm requires. Typically a speech buffer contains multiple frames.
FSK

Frequency Shift Keying; a type of analog modem signal that uses two frequencies to send ones and zeroes.
G.726

International Telecommunications Union (ITU) ADPCM standard.
gain (play, record)

An amplitude scaling (in dB) applied to played speech after de-compression or to recorded speech prior to compression.
glare

The simultaneous occurrence of an attempt to place a call and the appearance of an incoming call on the same line. In general, the incoming call must be given precedence.
Generalized Trunk Protocol (GTP) engine

A framework for controlling the signaling on a telephone line interface with a downloadable module called a Trunk Control Program (TCP).
ground start

A method of signaling between two telephony machines where one grounds one side of the line and the other detects the presence of ground.
hybrid

A circuit that interfaces a bidirectional transmission channel to separate receive and transmit channels.
in-band

Audio (voice) path of a telephone line interface.
informational event

An AG Access event for which there is no internal state change; these events are not automatically generated, but can be made available via the ADICALLCTL eventmask. Does not require any action by the application.
ISDN

Integrated Services Data Network; a standard for providing voice and data telephone service with all digital transmission and message based signaling.
IVR

Interactive Voice Response; a telephony application in which callers interact with a program using voice prompts, DTMF digits, speech recognition, etc., for querying or delivering information.
inter-pulse delay

The time between two active network tone pulses.
local loop

The voice-band channel connecting the subscriber to the central office.
loop start

The usual method of signaling an off-hook or line seizure, where one end closes the loop and the resulting current flow is detected by the switch at the other end.
MF Multi-Frequency; an in-band interoffice signaling method using pairs of frequencies from a set of six available frequencies.
MFC-R2

ITU standard line protocol for E1 lines using compelled MF tones. Note that almost every country has a variant of the standard.
muxhandle

Operating system-specific object used to wait for an AG Access event to be ready. (see adiOpenDriver)
MVIP

Multi-Vendor Integration Protocol; PCM digital bus standard for integrating various board vendors. Facilitates software-controlled digital switching within the PC chassis.
NMS

Natural MicroSystems Corporation.
NOCC (Null Protocol)

NO Call-Control; the TCP used when the application does not want to use AG Access protocol-independent call control. A stateless protocol which does not generate any call control events. This is typically used with low level functions which enable applications to perform call control from the host.
off-hook

The condition that indicates the active state of a customer telephone circuit. The opposite condition is on-hook.
OGT

Out-Going Trunk; a telephone line that is used only for placing calls.
out-of-band

Information carried outside of the audio or voice channel.
parameters

Variables that dictate the behavior of asynchronous functions.
parameter structures

Multiple parameters that are grouped together in "C" language structures.
PBX

Private Branch eXchange; a private branch telephone exchange system providing telephone switching in an office or building.
PCM

Pulse Code Modulation; a simple way of encoding voice signals in digital form.
pending command

An AG Access command that has been sent to the board, but has not yet been acknowledged with its associated event.
port

The primary object in AG Access on which telephony functions are performed. Physical and logical resources on the AG board are associated with a port.
port handle

Handle returned from adiOpenPort, which in turn is used for controlling most of the functions in AG Access. Addresses an AG Access port and the associated MVIP timeslot(s). Maps to an AG Access internal context that is referenced whenever a command is issued or an event is received on the port's behalf.
pulse width

The time during which a network tone is active.
protocol (telephony)

Defined procedure for call setup and call teardown.
protocol-independent

Used to describe AG Access' call control model. All telephony protocols can be represented by this single call control model.
reverse-make-busy

A change in out-of-band line signaling to block the remote end from offering any calls.
SIT

Special Information Tone; a series of 3 tones followed by an informational voice message indicating a network error such as congestion or an unknown telephone number.
SUCCESS

A return code that for asynchronous functions signifies the function was initiated. For synchronous functions, SUCCESS means that the function was completed. Note that for functions that require board resources, SUCCESS means that the commands necessary to execute the function on the board were delivered to the board. An error can still be returned in an event later.
SwitchPath

A switching library provided by Natural MicroSystems for MVIP compliant device drivers.
task processor

A single DSP on an AG board. Each task processor is configured to run one or more overlays (downloadable DSP software modules).
supervised transfer

A call transfer method in which the application controls the transfer process.
tone cycle

The time during which a network tone is active and then absent.
tone detector

Employs a precise tone filter to detect single or dual frequency tones.
transitional events

A protocol-independent call control event which causes a transition in AG Access' call control state machine.
trunk

A transmission channel connecting two switching machines.
Trunk Control Programs (TCPs)

A downloadable module which contains the low-level code to interface with an analog or digital trunk running a certain protocol. TCPs are specific to a trunk protocol, for example, one-way inbound with wink start (which is used for DID and DNIS).
WAVE

Microsoft file format supporting various speech encodings, typically PCM.
underrun

A gap in played or recorded speech caused because the host application did not provide speech buffers to the AG board in a timely fashion; the time limit is a function of the board buffer size and encoding data rate.