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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.
- abortmask
- In the CT Access ADI service, a bitmask used with the ADI service play and record functions to indicate which DTMF digits abort an active play or record operation. See also DTMF.
- ADI service
- A CT Access service that provides all AG board device-level functionality. 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. See also CT Access, service.
- 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. See also caller ID.
- AG
- Natural MicroSystems' Alliance Generation product line of telephony and voice processing hardware.
- 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. See also gain.
- AG driver
- The device driver on the host computer that provides the interface to the AG board(s).
- agmon
- Utility program which reads a configuration file and uses it to load and monitor 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 function
- Enables concurrent processing between hardware boards and the host CPU. In telephony, an application initiates functions on a telephony board and continues its own processing as it waits for the results of those functions. See also synchronous function.
- Automatic Gain Control
- See AGC.
- blind transfer
- Call transfer method in which a call control function places a second call and then disconnects its port from the PBX before call placement is resolved, connecting the original call.
- blocking (function call)
- Stopping the executing process or thread while waiting for an internal completion event or signal.
- blocking (telephone call)
- Call control action taken by an application to refuse any further incoming calls. Depending on the telephony protocol, blocking calls on a line will tell the CO (Central Office) or switch not to offer any calls, or the line will reject every call that is being offered. The rejection method also varies according to the telephony protocol being used. Some protocols allow an application to designate a particular rejection method, such as playing a busy signal or a reverse-make busy signal. See also CO, reverse-make-busy.
- call progress
- In CT Access, functions that allow the application to control and supervise call placement. Call progress monitors in-band energy to detect network tones, voice, and other tones such as modems.
- caller ID
- A telephone company service that delivers the calling party's number to the called party. For example, in one method, the data is delivered to the called party in the interval between the first and second incoming rings using an ADSI modem. See also ADSI.
- CAS
- Channel Associated Signaling; a signaling method where signaling information is provided on a line-by-line or channel-by-channel basis. Signaling information is sent for each channel at regular intervals, regardless of state changes. Each transmission channel is associated with one or more transmission paths. In-band signaling is a type of channel associated signaling. See also Common Channel Signaling (CCS).
- CED
- CallED tone; the 3-second 2100 Hz tone that a called fax terminal places on the line to indicate that the called station is a fax terminal. See also CO.
- Channel Associated Signaling
- See CAS.
- cleardown tone
- An in-band tone from the CO or switch indicating that the remote party has hung up. See also CO.
- client
- The requesting program or user in a client/server relationship. The computer handling the request is a server.
- client/server model
- A model for distributed computing in which one program, the client, makes a service request from another program, the server, which fulfills the request. In a network, the client/server model provides a convenient way to interconnect programs that are distributed across different locations.
- In telephony, a periodic reference signal used for synchronization on a transmission facility, such as a telephony bus.
- clock master
- The board that drives the clock signal for a system of boards connected by a bus cable. See also clock slave.
- clock slave
- A board that derives its clock signal from a bus cable; the clock signal is driven by the bus clock master. See also clock master.
- CO
- Central Office; the location of the public network switch.
- codec
- A coder/decoder device that converts digital signals to analog, and analog signals to digital.
- Common Channel Signaling (CCS)
- A signaling method that sends data packets of signaling information for a group of associated transmission channels over a separate link. This separate link is usually another channel of the same digital trunk, called the D (for data) channel in ISDN service. CCS sends signaling data only when one or more channels in the designated group experiences a state change. See also CAS.
- completion event
- The last event to be generated in response to a command, which generally indicates that the operation initiated by the command has completed. See also 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
- In CT Access, an entity that 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 that identifies a specific CTA context. See also CTA context.
- ctaqueuehd
- A handle that uniquely identifies a CT Access event queue. It provides access to events from one or more CTA contexts.
- ctdaemon
- The CT Access daemon process that enables developers to modify system global default parameters, set the global trace mask, and optionally log trace messages to a file.
- ctdaemon uses a configuration file (cta.cfg), to determine which CT Access services' compile-time parameter values will be placed in shared memory. ctdaemon's configuration file must specify all CT Access services used by applications that are expecting to use system global defaults. If parameters are shared among processes using system shared memory, then the ctdaemon must be running.
- dB
- See decibel(dB).
- 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.
- 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. See also CPE, PBX or PABX.
- 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. See also completion event.
- DSP
- In telephony, a 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 touchtone.
- echo cancellation
- An algorithm for removing a portion of the received signal determined to be echo by comparison with the output signal.
- encoding
- Any of several compression techniques for digitizing and compressing data.
- energy detector
- An algorithm for reporting the existence or 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.
- events
- In CT Access, data structures that contain notification of certain conditions or state changes. Events can be sent from the hardware or from another software module to the application program. All events are represented as C data structures. The event structure contains information about the specific event, including a timestamp, associated CTA context, specific data, error codes, or reason codes. For example, when a voice play operation completes, a completion event is returned to the application. See also completion event, DONE event.
- flat file
- A file that contains only data (no header or control information).
- FSK
- Frequency Shift Keying; a type of analog modem signal that uses two frequencies to send ones and zeroes.
- G.726
- An ITU ADPCM standard. See also ADPCM.
- gain
- An amplitude scaling (in dB) applied to played speech after decompression or to recorded speech prior to compression.
- Generalized Trunk Protocol
- See GTP.
- glare
- In telephony, 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. Also known as call collision.
- GTP
- Generalized Trunk Protocol; a framework for controlling the signaling on a telephone line interface with a downloadable module called a Trunk Control Program (TCP). See also TCP.
- in-band
- Audio (voice) path of a telephone line interface.
- informational event
- In CT Access, an event which does not indicate an internal state change and does not require any action from the application. Informational events are not automatically generated, but can be made available via an eventmask parameter.
- 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 recorded or synthesized voice prompts, DTMF digits, or speech recognition to query or deliver information.
- local loop
- The voice-band channel connecting the subscriber to the central office (CO).
- loop start (LS)
- A method of signaling an off-hook or a line seizure, where one end of the connection closes the loop circuit and the resulting current flow is detected by the switch at the other end.
- message
- In the CT Access Voice Message service, a block of encoded speech. For example, a message could be a greeting, or a spoken number in a collection of prompts.
- In the Diva SDK, Diva mail packets that travel from the DSP to the host.
- MF
- Multi-Frequency; an in-band interoffice tone-based signaling method using pairs of frequencies from a set of six available frequencies.
- 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 a CT Access 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. An interoperable subset of the H.100 bus standard.
- MVIP-90
- Original MVIP standard for hardware and software requirements for a standard telephony bus.
- MVIP-95
- Device driver specification for H-MVIP, H.100, and H.110 telephony buses.
- MVIP bus
- A high-speed, multiplexed digital telephony "highway" which allows boards to share data, signaling information, and switching information.
- nail up
- To make a permanent, dedicated assignment, as in nailing up a connection. Typically, a nailed up connection cannot be dynamically modified during an application's runtime, but can be changed by re-initializing the hardware and/or the application.
- NMS
- Natural MicroSystems Corporation.
- NMS ADPCM
- A form of ADPCM that requires less processing power than the CCITT standard and provides equivalent voice quality. See also ADPCM, PCM.
- NOCC
- NO Call Control; the trunk control program used when the application will not 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 to perform call control from the host. Also known as the NULL protocol. See also protocol (telephony), TCP.
- off-hook
- The active state of a 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.
- on-hook
- The inactive state of a customer telephone circuit. The term is derived from old telephone sets where the receiver, when not in use, was placed on a hook attached to a switch. The opposite condition is off-hook.
- OGT
- Out-Going Trunk; a telephone line that is used only for placing calls.
- OKI ADPCM
- A form of ADPCM encoding. See also ADPCM, PCM.
- out-of-band
- In telephony, information carried outside of the audio or voice channel.
- parameter
- A variable that dictates the behavior of functions.
- parameter structures
- Multiple parameters that are grouped together in C language structures.
- pattern
- In telephony, a repeated 8-bit sample applied to an output terminus of a switch block using messaging mode.
- PBX or PABX
- Private (Automatic) Branch telephone eXchange; a system providing local telephone switching in an office or building.
- PCM
- Pulse Code Modulation; a digital scheme for transmitting analog data. The signals in PCM are converted into binary data, which is then transmitted digitally.
- pending command
- A command that has been sent from the host to the hardware, but has not yet been acknowledged by the hardware returning its associated event.
- protocol (telephony)
- Defined procedure for call setup and call teardown.
- protocol-independent
- Consistent for all available protocols.
- 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 that blocks the remote end from offering any calls.
- service
- 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 enables device-independent programming.
- service managers
- Service managers implement CT Access services, communicate with the dispatcher, and adhere to CT Access standards. They are implemented as dynamic link libraries (DLLs) in Windows NT and as shared libraries in UNIX, and are linked to the application.
- signaling
- Information relayed between parties that is related to the process of a call (e.g., the status of the line, call progress and control information, etc.) rather than the content of the call (e.g., data or voice information).
- SIT
- Special Information Tone; a series of three tones followed by an informational voice message indicating a network error such as congestion or an unknown telephone number.
- stream
- A grouping of timeslots that usually corresponds to a particular bit-stream of time-domain multiplexed (TDM) serial data on an individual track or wire of a bus. See also TDM.
- 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.
- supervised transfer
- A call transfer method in which the application controls the transfer process. See also blind transfer.
- switching
- In computer telephony, making connections between telephony boards within a PC chassis both during and between phone calls. Enables an application to share resources and data across different telephony boards.
- Switching service
- A CT Access service that provides a set of functions for controlling switch connections on MVIP compliant or H.100 compliant switching devices. This service is based on the MVIP-95 switch model. It can be used with either the MVIP-95 switch model or the MVIP-90 switch model. See also MVIP.
- synchronous function
- A function that does not return until the operation it initiated has completed. See also asynchronous function.
- 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). See also DID, DONE event, loop start (LS), NOCC.
- Transfer Control Protocol; a transport layer protocol that offers connection-oriented, reliable, stream service between two hosts.
- 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.
- timeslot
- Specifies a particular 64 kbit/s subdivision of a TDM bus stream. Timeslots number from zero (0) to n where n is stream-dependent.
- tone cycle
- The time during which a network tone is active and then absent.
- tone detector
- A precise tone filter that enables an application to detect single or dual frequency tones.
- transitional event
- A protocol-independent call control event which causes a transition in a state machine.
- trunk
- A transmission channel connecting two switching machines.
- With regard to NMS products, a trunk is defined as the physical interface between the telephone network and the board. It can be used interchangeably with line because it could be connected to either a trunk or a line.
- In telephone networks, a trunk is a shared connection between two switches. It differs from a line in that it is not dedicated to one subscriber or extension. Trunks should have good machine-to-machine interfaces. Compared to lines, trunks have different signaling requirements, including possibly billing information.
- 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.
- Voice Message Service
- A CT Access service that provides a set of functions for playing, recording, and editing voice messages in files or memory.
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