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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.

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.

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.

AMI Alternate Mark Inversion; the line-coding format in T1 transmission systems where successive 1s (marks) are alternately sent with opposite polarity.

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

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

B8ZS Binary 8 Zero Substitution, a technique used to maintain required ones density in T1 communications.

B channel One of the timeslots on an E1 trunk or T1 trunk over which voice data and in-band signaling is passed. B channel is an abbreviation for bearer channel. See also D channel.

bearer channel See B channel.

bit An acronym for binary digit; the smallest piece of information; a specification of one of two possible alternatives: zero or one.

bus In the CT Access Switching service (MVIP-95), 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.

CAS Channel Associated Signaling; a signaling method where signalling information is provided on a line-by-line or channel-by-channel basis. In-band signaling is a type of Channel-Associated Signaling. See also Common Channel Signaling.

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

CEPT E1 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. Also referred to as E1.

channel 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.

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

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

CO Central Office; the place where the public network switch is located.

Common Channel Signaling
A signaling method where signaling information is provided for a number of channels in data-packet form sent over a separate link. This separate link is usually another channel of the same digital trunk, called a D channel in ISDN service.

CompactPCI A hardware standard which is electrically identical to standard PCI, but mechanically different, and uses a different form factor than standard PCI. CompactPCI boards can be removed from a computer without shutting down the system or an active application. See also hot swap, PCI.

compelled A protocol is "compelled" when transitions on one side wait on a positive corresponding transition by the other side (i.e hand shaking).

completion event The last event to be generated in response to a command. See DONE event.

conference bridge A device used to allow three or more parties to talk on the same call.

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

coprocessor A microprocessor on the AG board. Runs manager code to enable high level communication between the host and the other AG board resources (DSP and MVIP).

CSU Channel Service Unit; A device connecting customer T1 equipment and a network line.

CT_NETREF Secondary reference clock. Used as a backup reference clock in H.100 systems.

CT Access Natural MicroSystems' development environment for telephony applications.

D-4 framing A framing format in the T1 environment. There are 12 separate 193-bit frames in a D-4 superframe. The D-4 framing bit is used to identify both the channel and the signaling frame. In D-4 framing, signaling for voice channels is carried in-band along with the encoded voice. See also robbed-bit-signaling.

D channel The timeslot on an E1 trunk or on a T1 trunk in which common channel signaling information is passed. See also B channel, Channel Associated Signaling, and Common Channel Signaling.

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.

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

Digital Signal Processor
See DSP.

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 touchtone.

E1 See CEPT E1.

E & M Ear and Mouth; a telephone signaling system used between two switches that uses two wires called the E lead and the M lead. In analog E & M, the M lead of one switch is connected to the E lead of the other, and vice versa. In digital E & M signaling, the A bits and B bits are used. A common mnemonic is that E stands for ear-lead and M for mouth-lead.

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.

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.

fax Facsimile machines for sending and receiving images and written material. Almost all fax machines today use the CCITT Group 3 protocol. A higher performance protocol, CCITT Group 4, is available for ISDN.

FMIC Flexible MVIP Integrated Circuit. Single chip which implements MVIP-90 switching.

frame (T1/E1) A portion of a PCM data stream that contains one binary data word, typically 8 bits, for each unidirectional channel. A frame usually will also contain control and synchronization bits and is 125 msec long.

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

Generalized Trunk Protocol engine
See GTP.

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.

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).

H.100 Telephony bus which is an interoperable superset of the H-MVIP and MVIP-90 telephony buses.

HMIC H.100/MVIP Integrated Circuit. The HMIC is a single chip that offers full support for the H.100 bus within the MVIP architecture providing access to all 4096 slots on the H.100 bus.

host The PC CPU where the host application runs.

hot swap Ability to perform "live" insertion and removal of hardware components without disrupting the host system or application.

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

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

Kbit/s Kilobits per second, 1000 bits per second.

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.

MFC-R2 ITU standard line protocol for E1 lines and T1 lines using compelled MF tones. Almost every country has a variant of this standard.

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.

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 on a PC.

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

MVIP Enhanced Switching Compliant Device
A network device with a switch implementing all possible connections of the MVIP switch model.

MVIP Standard Switching Compliant Device
A network device with a switch that does not implement the full MVIP switch model but does support port-to-MVIP connections for all MVIP timeslots, both forward and reverse.

MVIP Switching Compatible Device
A network device with an MVIP switch that does not fully meet the MVIP standard or MVIP enhanced compliance standards.

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.

nail up To make a permanent assignment, as in nailing up a connection.

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.

NOCC (Null Protocol) 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 which enable applications to perform call control from the host.

OKI ADPCM A form of ADPCM used on some voice boards.

ones density The requirement for digital transmission lines in the PSTN that eight consecutive zeros cannot exist is a digital data transmission. On a T1 line, zero (0) means no voltage, no pulse.

overlay Software that is not always memory resident; it is loaded on request.

parameters Variables that dictate the behavior of functions.

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.

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.

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

Pulse Code Modulation
See PCM.

pulse dialing The method used on rotary-dial telephones to signal a telephone number for automatic switching. Each digit is encoded as a series of one to ten pulses, which are brief interruptions of current flow on the line. See also DTMF.

robbed-bit signaling The least significant bit of each timeslot in every sixth frame conveys voice-related signaling information (on-hook, off-hook, etc.) for that voice channel. See also D-4 framing.

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.

standard switching compliant
See MVIP Standard Switching Compliant Device.

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 compatible See MVIP Switching Compatible.

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.

T1 A standard for telephone transmission that multiplexes 24 digital voice channels on a single 1.544 Mbps carrier.

T1 trunk A digital trunk used for channel associated signaling in the US.

task processor A single DSP chip on a board. Each task processor is configured to run one or more overlays (downloadable DSP software modules).

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.

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 detector A precise tone filter to detect single or dual frequency tones.

trunk A transmission channel connecting two switching machines.

Trunk Control Programs
See TCP.

trunk signaling See signaling.

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

VOX A voice file format which can contain multiple messages and allows messages to be edited.

WAVE Microsoft file format supporting various speech encodings, typically PCM.

wink An out-of-band signaling method that simulates an off-hook condition for a brief period.

ZCS Zero Code Suppression; the insertion of a one bit to prevent the transmission of eight or more consecutive zero bits. Used primarily with T1 facilities which require a minimum ones density. See also ones density.



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