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Appendix A


2500-type set
The standard single-line analog touchtone desk telephone.

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.

In telephony, the number dialed by a calling party which identifies the party called. Also known as the telephone number.

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. Note that the call control functions in the ADI service have been supplanted by the NCC service. See also CT Access, NCC service, service.

Natural MicroSystems' Alliance Generation product line of telephony and voice processing hardware.

AG configuration file
Text file (usually named ag.cfg) that provides configuration information for all AG boards in a system. The AG configuration file also specifies runtime software such as DSP files and TCPs to download to the AG board(s) as part of board initialization. agmon uses the AG configuration file to initialize and load the AG boards in the system. See also agmon, TCP.

AG driver
The device driver on the host computer that provides the interface to the AG board(s).

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

Information represented by a continuous and smoothly varying signal amplitude or frequency. See also digital.

Automatic Number Identification; a network service that provides a called party with the phone number of the calling party. It is typically available to the called party in R1, R2, and ISDN signaling systems. The implementation of ANI can vary between different telephone companies and even different central office switches. See also caller ID.

Application Programming Interface; a library of function calls that allow an application developer to access functionality in a uniform and consistent way.

American Standard Code for Information Interchange; a standard used for numeric representation of alphanumeric characters.

Refers to circuitry and operations without a common timing or clock signal.

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.

B channel
A timeslot on an E1 trunk, T1 trunk, or telephony bus that carries voice data and in-band signaling. B channel is an abbreviation of bearer channel. See also D channel, ISDN.

The difference between the highest and lowest frequencies of a transmission channel; in general, when bandwidth increases, so does the quantity of information that can be sent through the circuit during a given time period.

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 (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.

A data area that can be shared by hardware devices or program processes. It functions as a "midpoint holding place."

bus (telephony)
A physical system which permits the interchange of data. A telephony bus has three basic elements: lines for the data, bit synchronization (clocks), and frame synchronization (frame strobe). Most telephony buses also have a network reference - an 8 kHz timekeeper. See also H.100 bus, MVIP.

In the CT Access Switching service, specifies the interface point of the switch block. Devices can reside directly on the telephony bus. Devices can also reside on a board's local bus and may require a switch block to access the telephony bus. See also Switching service.

call control
Any part of telephone call establishment, including setting up, blocking, monitoring, transferring, releasing, or tearing down the telephone call.

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 ANI.

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).

Business telephone service offered by the CO. Features typically include call forwarding, call transfer, call hold/retrieve, and others.

Conference of European Postal and Telecommunications administrations; a European telephony standards committee.

A standard used in Europe for digital telephone carriers. CEPT E1 is similar to T1 but operates at 2.048 Mbps and has 32 channels instead of T1's 24. See also T1.

An electronic communications path. In digital telephony, a channel usually refers to a separate connection carried on a digital trunk.

Channel Associated Signaling
See CAS.

circuit-switched network
A type of wide area network where transmitting and receiving networks are linked by a single physical circuit, which is created by complex switching mechanisms. See also PSTN.

[to] clear backward
To send a signal to a remote party that indicates a clear forward signal was received and obeyed.

[to] clear forward
To send a signal to a remote party requesting it to hang up.

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.

Central Office; the location of the public network switch.

A coder/decoder device that converts digital signals to analog, and analog signals to digital.

Instructions sent from the application to the host or the hardware. Invoking CT Access API functions sends commands from the application to the services.

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 B channel, CAS, D channel.

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.

In telephony, a path between two entities that enables them to share and/or transfer voice and signaling data. For example, a continuous electrical circuit between two wires or units, or a data path between two channels (unique stream/timeslot assignments) on a time-division multiplexed data stream.

In AG hardware architecture, a microprocessor on the AG board. Runs manager code to enable high-level communication between the host and other AG board resources (such as DSPs and the MVIP bus).

Customer Premise Equipment; customer-owned equipment connected to telephone company lines.

Canadian Standards Association; CSA certification is required for most electrical equipment used in Canada.

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.

The handle returned by ctaCreateContext that identifies a specific CTA context. See also CTA context.

A handle that uniquely identifies a CT Access event queue. It provides access to events from one or more CTA contexts.

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.

D channel
The timeslot on an E1 trunk, a T1 trunk, or telephony bus in which common channel signaling information is passed. See also B channel, CAS, Common Channel Signaling (CCS), ISDN.

A decompression technique used for changing a digital signal into an analog signal or into another type of digital signal.

device driver
Software which translates the application commands into the code required by the device.

device service
A CT Access service that communicates directly with the hardware providing the functionality.

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.

DID number
Direct Inward Dial number; the called number which is collected by the trunk control program and is passed to the application.

Information in a discrete or quantized form. See also analog.

Digital Signal Processor
See DSP.

Dynamic Link Library; a library of software object modules that can be loaded and accessed on demand.

Department of Communications; the Canadian government agency that regulates communications and the use of the electromagnetic spectrum.

DONE event
An event which signifies the completion of an asynchronous function. See also completion event.

In telephony, a Digital Signal Processor; a microprocessor that is designed to perform the calculations required for voice processing.

Dual-Tone-Multi-Frequency; an in-band signaling system that uses two simultaneous voice-band tones for dialing. Also called touchtone.

Dynamic Random Access Memory
See DSP.

See CEPT E1.

Any of several compression techniques for digitizing and compressing data.

European Telecommunication Standards Institute.

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.

event queue
In CT Access, the single queue created by calling ctaCreateQueue where the application receives all of its events from the telephony hardware. NMS software is event-driven. CT Access provides functions to wait for and retrieve events from the event queue.

Federal Communications Commission; the US government agency that regulates and monitors interstate communications, and the use of the electromagnetic spectrum.

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.

H.100 bus
A PCM digital bus standard for integrating hardware from various PC board vendors which enables boards to share voice data, signaling data, and switching information. The H.100 bus is an interoperable superset of the H-MVIP and MVIP-90 telephony buses. It can be addressed using the MVIP-95 switch model. See also bus, H-MVIP, MVIP-90, MVIP-95.

H.110 bus
The Telephony bus which is a specific implementation of the H.100 bus streams and clocks, but redefines CT_NETREF as CT_NETREF_1 and adds CT_NETREF_2. It is implemented on a CompactPCI backplane at the J4 location.

The bus cable hardware standard for MVIP-95. See also MVIP-95.

The PC on which an application runs. Also used to designate a computer with full two-way access to a network such as local area network or the Internet.

Audio (voice) path of a telephone line interface.

in-band signaling
A signaling method in which information is carried as audio signals that are transmitted in the voice band. Touchtone dialing is a familiar example. See also out-of-band signaling.

inbound application
An application designed to receive inbound calls.

inbound call
A call received by an inbound application, placed by a remote party.

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.

International Organization for Standardization (ISO)
The standards organization that developed the OSI seven-layer protocol model.

International Telecommunications Union
See ITU.

Industry Standard Architecture; the de-facto bus card standard in the IBM-PC compatible world. Also known as the PC/AT bus.

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

See International Organization for Standardization (ISO).

International Telecommunications Union; an international standards body for telecommunications.

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.

A logical telephone connection on which a call can take place.

line seizure
The process by which a switch or station instrument (phone) takes control of a telephone circuit.

Multi-Frequency; an in-band interoffice tone-based signaling method using pairs of frequencies from a set of six available frequencies.

Millions of Instructions Per Second; measure of computer speed according to the average number of machine language instructions performed by the CPU in one second.

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.

To transmit more than one signal or channel over a single physical circuit.

Operating system-specific object used to wait for a CT Access event to be ready.

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. See also H.100 bus, H.110 bus.

Original MVIP standard for hardware and software requirements for a standard telephony bus.

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. See also bus.

MVIP switch model
An abstract representation of the logical switching capabilities that can be located on one physical network interface device.

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.

NCC service
A CT Access service which performs call control. NCC service features include a protocol-independent API, separate call and line state machines, call hold/retrieve, and the ability to query a protocol's capabilities. The NCC service supplants the call control functions provided by the ADI service.

In telephony, short for the telephone switching network. See also PSTN.

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. Not supported by the NCC service. See also protocol (telephony), TCP.

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.

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.

outbound application
An application designed to place outbound calls.

outbound call
A call placed by an application to a remote party.

In telephony, information carried outside of the audio or voice channel.

out-of-band signaling
Refers to signaling methods where signaling information is carried by a separate channel. In addition to technical advantages, out-of-band signaling helps prevent unauthorized tampering with the network. See also in-band signaling.

A variable that dictates the behavior of functions.

parameter structures
Multiple parameters that are grouped together in C language structures.

Private (Automatic) Branch telephone eXchange; a system providing local telephone switching in an office or building.

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.

.pf file
Parameter definition file; used to automatically generate parameter source and header files.

A point of connection, such as:

protocol (telephony)
Defined procedure for call setup and call teardown.

Consistent for all available protocols.

Public Switched Telephone Network; a public telephone network.

Data structure containing device information relative to all instances of the CT Access service.

The NMS board family which features low port telephony and voice processing hardware.

reason code
Further classification for a DONE event, typically indicating an application problem. See also DONE event.

Mandatory low-level runtime software which is downloaded to an AG board as part of its initialization. The runfile for a board is specified in the AG configuration file. When agmon runs, it transfers the runfile from the host into on-board memory. See also agmon.

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 API
In CT Access, a set of function calls, including arguments and managed parameters, return values, and asynchronous events that define the work that is done by the service.

service ID
16-bit numeric value embedded in all commands, errors, and event messages of a CT Access service.

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. See also DLL.

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).

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.

solicited event
An event that occurs as a consequence of some function call.

special information tone
See SIT.

Signaling System 7; an out-of-band signaling system that provides fast call setup (using circuit-switched connections) and transaction capabilities for remote database interactions.

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.

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.

In telephony, a device that can connect one of several inputs to one of several outputs.

switch block
The switch on a telephony board that connects the telephone network to the telephony bus. The logical switch is normally referred to as the switch block because it may consist of one or more physical switches or chips.

switch handle
In CT Access, identifies an open MVIP or H.100 switching device and allows access to the corresponding switch block.

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 H.100 bus, MVIP.

synchronous function
A function that does not return until the operation it initiated has completed. See also asynchronous function.

A standard for telephone transmission that multiplexes 24 digital voice channels on a single 1.544 Mbyte/s carrier.

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, NOCC.

Transfer Control Protocol; a transport layer protocol that offers connection-oriented, reliable, stream service between two hosts.

Telephony Services Architecture
See TSA.

Specifies a particular 64 kbit/s subdivision of a TDM bus stream. Timeslots number from zero (0) to n where n is stream-dependent.

transitional event
A protocol-independent call control event which causes a transition in a state machine.

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.

trunk signaling
See signaling.

Telephony Services Architecture; the NMS model of managing telephony and media functionality in computer systems.

unsolicited events
Events that are not generated in response to a command.

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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Copyright © 1999, Natural MicroSystems, Inc. All rights reserved.