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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.
- 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.
- 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.
- 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.
- bus In the CT Access Switching service, specifies the interface point of the switch block. Devices can reside directly on the MVIP bus. Devices can also reside on a board's local bus and may require a switch block to access the MVIP bus.
- 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.
- clock A timing reference signal, e.g., on an MVIP bus.
- CO Central Office; the place where the public network switch is located.
- Codec A device that converts digital signals to analog, and vice versa.
- 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.
- connection (MVIP) Connects an input terminus to an output terminus. The input and output terminuses can have the same or different buses and streams. See also terminus.
- 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.
- 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.
- 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.
- 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®.
- 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 C data structures. 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.
- ground start A method of signaling between two machines where one machine grounds one side of the line and the other machine detects the presence of ground.
- 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.
- in-band Audio (voice) path of a telephone line interface.
- local loop The voice-band channel connecting the subscriber to the central office (CO).
- loop start A method of signaling an off-hook or line seizure, where one end closes the loop circuit and the resulting current flow is detected by the switch at the other end.
- 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 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.
- 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.
- 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.
- pattern An 8 bit sample that is sent out of an output terminus or into an input terminus of a switch block.
- PBX or PABX Private (Automatic) Branch Telephone eXchange; a system providing local telephone switching in an office or building.
- PSTN Public Switched Telephone Network; a public telephone network.
- resource boards In an MVIP system, boards that perform processing functions, such as voice processing, voice recognition, FAX sending and receiving, but do not have switching capabilities.
- In MVIP-95, these boards transmit on even-numbered streams and receive on odd-numbered streams.
- service managers Dynamic link libraries (DLL) in Windows NT and OS/2 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.
- 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.
- switch block The switch on boards that interface the telephone network to the MVIP bus. This switch is normally referred to as the switch block because it may consist of one or more physical switches. It may be either MVIP-compatible or MVIP-compliant.
- switch handle Identifies an open MVIP switching device and allows access to the MVIP switch block.
- 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.
- terminus In the CT Access Switching service, a single access point to a switch block input or switch block output. A terminus contains a bus, a stream, and a timeslot.
- time division multiplexing
See TDM.
- timeslot Specifies a particular 64 kbit/second subdivision of a TDM bus stream. Timeslots number from zero (0) to n where n is stream- dependent.
- 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.
- 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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