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Appendix A
Glossary
- A-law An encoding scheme that determines how an analog speech signal is converted to a digital signal. A-law encoding is used in Europe. The other algorithm, mu-law, is used in North America and Japan. See also mu-law.
- abort mask A bitmask used with the play and record functions to indicate which DTMF digits abort the respective function. See also DTMF.
- ADI Service Service providing all AG device-level functionality for CT Access. The ADI service is supported by Natural MicroSystems' AG boards. Functions are provided for establishing and maintaining network connections, determining call status, playing and recording voice messages, and generating and detecting DTMF and other tones.
- 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. For example, used in caller ID.
- AG Natural MicroSystems' Alliance Generation product line of telephony and voice processing hardware and software, including highly integrated hardware modules.
- AGC Automatic Gain Control; an algorithm applied to incoming speech before compression and storage so that the amplitude of the stored speech is kept at a target level.
- AG driver The hardware device driver that allows AG Access to communicate with all AG boards in a host system.
- agmon Utility program which reads a configuration file and uses it to load and monitor the AG hardware.
- API Application Programming Interface; a library of function calls that allow an application developer to access functionality in a uniform and consistent way.
- ASCII American Standard Code for Information Interchange; a standard used for numeric representation of alphanumeric characters.
- asynchronous programming
Enables concurrent processing between hardware boards and the host CPU. The application initiates telephony functions on the AG board and continues its own processing instead of waiting for the event from the AG board to arrive. AG Access and CT Access support this model.
- Automatic Gain Control
See AGC.
- blocking An API call is blocking if it waits for an internal completion event before proceeding.
- blocking 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, or to reject every call that is being offered (not answer, or play busy, etc.). See also reverse-make-busy.
- blocking system A switching system that does not have enough switching capability to allow all possible sets of connections to be made. Under some circumstances, a connection cannot be made and the call is said to be blocked.
- caller ID A telephone company service that delivers the calling party's number between the first and second incoming ring by means of modem signals.
- call progress Functions that allow the application to control call placement. Call progress monitors in-band energy to detect network tones, voice, and other tones such as modems.
- cleardown tone An in-band tone from the CO or switch indicating that the remote party has hung up.
- CO Central Office; the place where the public network switch is located.
- commands Instructions sent by the application via CT Access to the services.
- completion event The last event to be generated in response to a command. See DONE event.
- CPE Customer Premise Equipment; customer-owned equipment connected to telephone company lines.
- CT Access Natural MicroSystems' development environment for telephony applications.
- CTA context Organizes services and accompanying resources around a single processing context. Usually represents an application instance controlling a single telephone call. Some contexts are not associated with a call; an application performing voice conversions does not require a telephone line.
- ctahd The handle returned by ctaCreateContext.
- ctaqueuehd A handle managed by CT Access to access events from one or a group of CTA context handles.
- ctdaemon The CT Access daemon process. If parameters are shared among processes using system shared memory, then the ctdaemon must be running.
- current gain See gain.
- current message In the CT Access Voice Message service, when you play a message or a list of messages, the message or list becomes the current message for pausing, resuming, repositioning, etc. It is associated with the CT Access context handle and has a current position.
- current position In the CT Access Voice Message service, the current milliseconds offset into the current message.
- dB See decibel.
- dBm A unit of measure of absolute power level, defined as the number of decibels above or below a level of one milliwatt.
- decibel (dB) A unit of measure of relative power or voltage in terms of the ratio of two values. dB = 10 log (P1/P2), where P1 and P2 are the power level in watts.
- dispatcher Handles the routing of commands and events between services and between the services and the application. The dispatcher provides the functionality for opening and closing services, creating queues, creating contexts, managing parameters, tracing, and logging errors.
- DLL Dynamic Link Library; a library of software object modules that can be loaded and accessed on demand.
- DONE event An event which signifies the completion of an asynchronous function.
- DSP Digital Signal Processor; a microprocessor that is designed to perform the calculations required for voice processing.
- DTMF Dual-Tone-Multi-Frequency; an in-band signaling system that uses two simultaneous voice-band tones for dialing. Also called Touch-Tone®.
- 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 nonexistence 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.
- event queue The single queue (created by calling ctaCreateQueue) where the application receives all of its events. CT Access provides functions to wait for and retrieve events from the queue. The NMS software is event driven. The events coming from an AG board are placed in an event queue.
- events Data structures that contain notification of certain conditions or state changes sent from the hardware or service to the application program. All events are represented as a C data structure. The structure informs the application what event occurred and provides additional information specific to the event. An indication that playing a message is done is a typical event. See also DONE event.
- flat file Files that contain only data (no header).
- frame (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 decompression 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.
- H-MVIP The hardware standard for MVIP-95.
- Hertz (Hz) The unit of frequency. One hertz equals one cycle per second.
- hybrid A circuit that interfaces a bidirectional transmission channel to separate receive and transmit channels.
- Hz See Hertz.
- IMA ADPCM The Intel/DVI ADPCM standard. See also OKI ADPCM.
- in-band Audio (voice) path of a telephone line interface.
- informational event An event for which there is no internal state change; these events are not automatically generated, but can be made available via an eventmask parameter. Does not require any action by the application.
- inter-pulse delay The time between two active network tone pulses.
- 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.
- local loop The voice-band channel connecting the subscriber to the central office (CO).
- message A block of encoded speech. For example, a message could be a greeting message or a spoken number in a collection of prompts.
- message number In the CT Access Voice Message service, a number identifying a message in a voice object. Message numbers start with zero (0).
- message text A descriptive string which can be attached to a message in a NMS VOX file.
- mu-law One of two algorithms used in telephony to logarithmically compress or expand digitized speech. mu-law is used in North America and Japan. A-law is the other algorithm used in European networks. See also A-law.
- muxhandle Operating system-specific object used to wait for an event to be ready.
- MVIP Multi-Vendor Integration Protocol; PCM digital bus standard for integrating various board vendors. Facilitates software-controlled digital switching within the PC chassis. MVIP interconnects switching and telephony processing boards on a PC.
- MVIP connection See connection (MVIP).
- nail up To make a permanent assignment, as in nailing up a connection.
- NMS Natural MicroSystems Corporation.
- NMS ADPCM A form of ADPCM that requires less processing power than the CCITT standard.
- NOCC (Null Protocol) NO Call-Control; the trunk control program used when the application does not want to use protocol-independent call control. NOCC is a stateless protocol which does not generate any call control events. It is typically used with low-level functions which enable applications to perform call control from the host.
- off-hook The active state of a customer telephone circuit. The term is derived from old telephone sets where the receiver, when in use, was lifted from a hook attached to a switch. The opposite condition is on-hook.
- OKI ADPCM A form of ADPCM used on some voice boards.
- out-of-band Information carried outside of the audio or voice channel.
- parameters Variables that dictate the behavior of functions.
- parameter structures Multiple parameters that are grouped together in C language structures.
- PBX or PABX Private (Automatic) Branch Telephone eXchange; a system providing local telephone switching in an office or building.
- PCM Pulse Code Modulation; a communication technique where the information to be sent is converted into binary numbers which are then transmitted on the signal.
- pending command A command that has been sent, but has not yet been acknowledged with its associated event.
- prompt A voice message that is typically a short message used in a menu.
- protocol (telephony) Defined procedure for call setup and call teardown.
- protocol-independent Used to describe call control model. All telephony protocols can be represented by this single call control model.
- PSTN Public Switched Telephone Network; a public telephone network.
- Pulse Code Modulation
See PCM.
- pulse width The time during which a network tone is active.
- reverse-make-busy A change in out-of-band line signaling to block the remote end from offering any calls.
- service managers Dynamic link libraries (DLL) in Windows NT and shared libraries in UNIX which are linked to the application. Service managers implement services, execute within the CT Access environment, and adhere to standard CT Access interfaces.
- services In CT Access, a group of logically related telephony functions. A service may be implemented on multiple hardware boards. No matter what hardware is providing the functionality, all services with the same functionality have a standard API. This allows device-independent programming.
- signaling The transmission of information about a line's on-hook or
off-hook status and various related signals including those that deliver address information.
- 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.
- switching Changing the connections on different boards within a PC platform both during and between phone calls.
- Switching service A CT Access service that provides a set of functions for controlling Multi-Vendor Integration Protocol (MVIP) switch blocks on MVIP compliant switching devices. This service is based on the MVIP-95 device driver standard. It may be used to access MVIP-95 and MVIP-90 device drivers.
- SwitchPath A switching library provided by Natural MicroSystems for MVIP-90 compliant device drivers.
- synchronous function A function that does not return until its operation is complete.
- TCP Trunk Control Program; 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).
- TDM Time Division Multiplexing; a technique for transmitting a number of separate data, voice, and/or video signals simultaneously over one communications medium by quickly interleaving a piece of each signal one after another.
- Telephony Services Architecture
See TSA.
- time division multiplexing
See TDM.
- 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.
- trunk A transmission channel connecting two switching machines.
- Trunk Control Programs
See TCP.
- TSA Telephony Services Architecture; the NMS model of managing telephony and media functionality in computer systems.
- underrun A gap in played or recorded speech caused because the host application did not provide speech buffers to the board in a timely fashion. The time limit is a function of the board buffer size and encoding data rate.
- unformatted files See flat files.
- voice handle Handle of an open voice object.
- voice object A file or a memory block containing voice messages.
- Voice Message Service
A CT Access service that provides a set of functions for playing, recording, and editing voice messages in files or memory.
- VOX A voice file format which can contain multiple messages and allows messages to be edited.
- Wait object Operating system dependent objects that signal requests for services when waited upon in an OS dependent manner. These objects are managed by the dispatcher on specific ctaqueuehds.
- WAVE Microsoft file format supporting various speech encodings, typically PCM.
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