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Appendix A


A bit One of four bits used to carry channel associated signaling on digital trunks and on MVIP signaling streams. The others are called the B, C and D bits. Many protocols do not use all four bits. Usually, only the A and B bits are used in North America, while all four are used in Europe.

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.

ABCD bits The signaling bits used in channel associated signaling. The value that these bits take determines or indicates the state of the telephone channel.

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.

AG Natural MicroSystems' Alliance Generation product line of telephony and voice processing hardware and software, including highly integrated hardware modules.

analog Information represented by a continuous and smoothly varying signal amplitude or frequency. Opposite of digital.

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

B bit See A bit.

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.

C bit See A bit.

clock A timing reference signal, e.g., on an MVIP bus.

clock master The board that sources the clocks in an MVIP system.

connection (MVIP) Connects an input terminus to an output terminus. The input and output terminuses can have the same or different buses and streams.

CT Access Natural MicroSystems' software development environment for telephony applications.

D bit See A bit.

digital Information in a discrete or quantized form. Opposite of analog.

Digital Signal Processor
See DSP.

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

DSi0-7, DSo0-7 Nomenclature for the individual unidirectional bit streams on the MVIP-90 bus. By convention, they are paired up (DSiX, DSoX) to form the eight full duplex MVIP-90 streams. DSi0-7 are designated for input to resource boards and DSo0-7 are designated for output from resource boards.

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.

enhanced switching compliant
See MVIP Enhanced Switching Compliant.

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.

FPGA Field Programmable Gate Arrays. Circuit used by QX 2000 boards for internal glue logic.

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

full duplex Simultaneous two-way voice and two-way signal data transmission.

Hertz (Hz) The unit of frequency. One hertz equals one cycle per second.

host The PC CPU where the host application runs.

Hz See Hertz.

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

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.

MIPS 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.

msec Millisecond (1/1000 of a second).

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.

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 in a PC.

MVIP bus A high-speed, multiplexed digital telephony "highway" which allows boards to share data, signaling information, and switching information.

MVIP bus adapter An adapter board which allows H.100 boards to access streams on the MVIP-90 bus.

MVIP connection See connection (MVIP).

MVIP enhanced switching compliant device
A network device with a switch implementing all possible connections of the MVIP switch model.

MVIP switch model An abstract representation of the most general switching capabilities that can be located on one network interface device. However, a particular network interface device need not implement all of the switching capabilities of the switch model.

network In telephony, short for the telephone switching network.

NMS Natural MicroSystems Corporation.

NMS ADPCM A form of ADPCM that requires less processing power than the CCITT standard.

non-blocking system A switching system that has enough switching capability to allow all possible sets of connections to be made. See also blocking system.

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.

on-hook The active 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.

pattern An 8-bit sample that is sent out of an output terminus or into an input terminus of a switch block.

PCI Peripheral Component Interconnect; A 32/64 bit local bus inside a PC.

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.

port An external connection between the MVIP bus and anything else, including telephone trunks, human operators, voice processors, FAX processors, etc.

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.

QSLAC Quad Subscriber Line Audio Circuits. Audio circuits which are programmable to comply with country-specific line parameters.

qxload Utility program which reads a configuration file and uses it to load and configure the QX 2000 hardware.

ring The alerting signal to the subscriber or terminal equipment; also the name for one conductor of a wire pair, designated by R. The other is called tip, or T. See also tip.

service managers Dynamic link libraries (DLLs) 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.

stream A grouping of timeslots that usually corresponds to a particular bit stream of time-division multiplexed (TDM) serial data on an individual track or wire of a bus.

switch In telephony, a device that can connect one of several inputs to one of several outputs. Switches can range in size from an integrated circuit to an entire build-ing.

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.

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.

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 sub-division of a TDM bus stream. Timeslots number from zero (0) to n where n is stream- dependent.

tip One conductor of a wire pair, designated by T; usually the more positive of the two. The other is called ring. See also ring.

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

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