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Appendix A

Glossary

A B C D bits

The four signaling bits used in channel associated signaling. The value that these bits take determines or indicates the state of the telephone channel. Many protocols do not use all four bits. Usually, only the A and B bits are used in North America, but all four are used in Europe. See also CAS.
A bit

See also A B C D bits.
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

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.
AG 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, DSP file, TCP.
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.
AIS

Alarm Indication Signal; a signal that replaces the normal traffic signal when a maintenance alarm indication has been activated. An AIS is transmitted downstream indicating that an upstream failure has occurred. See also blue alarm, red alarm, yellow alarm.
Alarm Indication Signal

See AIS.
AMI

Alternate Mark Inversion; the line-coding format in T1 transmission systems where successive ones (marks) are alternately sent with opposite polarity, to reduce cross-talk. See also cross-talk, T1.
analog

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

Refers to circuitry and operations without a common timing or clock signal.
B8ZS

Binary 8 Zero Substitution; a technique used to maintain required ones density in T1 communications. See also ones density.
B bit

See A B C D bits.
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.
back end power

Power to the back end logic; back end power is applied to the back end logic through the power isolation circuitry.
blocking system

A switching system with limited switching capability cannot make all possible sets of connections. Under some circumstances, a connection cannot be made and the call is blocked. See also non-blocking system.
blue alarm

One of the three alarms to indicate problems with T1/E1 transmissions. The blue alarm occurs when two consecutive frames have fewer than three zeros in the data stream. A blue alarm sends ones in all bits of all timeslots. Also known as the AIS. See also AIS, red alarm, yellow alarm.
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.
C bit

See A B C D bits.
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).
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. See also T1.
channel

See port.
Channel Associated Signaling

See CAS.
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.
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.
CompactPCI

A PICMIG hardware standard which is electrically identical to standard PCI and based on the mechanical form factor of VME to provide a rugged, industrial package. Individual cards conform to the VME 6U height. CompactPCI can provide high availability through hot swap. See also PCI, PICMG.
connection

Connects an input terminus to an output terminus. The input and output terminuses can refer to the same or different buses and streams. See also terminus.
coprocessor

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).
cross-talk

Undesired voice-band energy transfer from one circuit to another. Usually, the circuits are physically adjacent and analog.
CT_NETREF

A secondary reference clock, used as a backup reference clock in H.100 systems. This clock can be 1.544 MHz, 2.048 MHz, or 8 KHz.
CT_NETREF_1

A secondary reference clock, used as a backup reference clock in H.110 systems. This clock can be 1.544 MHz, 2.048 MHz, or 8 KHz.
CT_NETREF_2

A secondary reference clock, used as a backup reference clock in H.110 systems. This clock can be 1.544 MHz, 2.048 MHz, or 8 KHz.
CT Access

Natural MicroSystems' development environment for telephony applications.
D4 framing

A framing format in the T1 environment. The D4 framing bit is used to identify both the channel and the signaling frame. In D4 framing, signaling for voice channels is carried in-band along with the encoded voice. A pattern derived from the framing bit of each individual frame is used to maintain synchronization. See also robbed-bit signaling.
D bit

See A B C D bits.
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).
digital

Information in a discrete or quantized form. See also analog.
Digital Signal Processor

See DSP.
DLL

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

Dynamic Random Access Memory chip; RAM memory that requires data to be refreshed periodically to prevent its loss in memory. See also SRAM.
DSi0..7, DSo0..7

The names of the physical bus wires in the MVIP-90 bus cable that carry the individual unidirectional bit streams. By convention, they are paired up (DSiX, DSoX) to form eight full-duplex MVIP streams. DSi0..7 are designated for input to resource boards and DSo0..7 are designated for output from resource boards.
DSP

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

A low-level program, downloaded to an AG board at initialization, that enables an AG board's DSPs to perform tasks such as DTMF signaling, voice recording, and playback.
DTMF

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 DRAM.
E1

See CEPT E1.
encoding

Any of several compression techniques for digitizing and compressing data.
enhanced switching compliant

See MVIP Enhanced Switching Compliant device.
ESF

Extended SuperFrame; a framing format in the T1 environment. There are 24 separate 193 bit frames in an Extended Superframe. The 24 framing bits, one from each individual frame, are used to maintain synchronization in a manner similar to D4 framing, provide error checking, and provide a diagnostic channel. In-band signaling is employed using robbed-bit signaling. See also D4 framing, robbed-bit signaling, T1.
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.
four-wire

In analog telephony, a transmission path that requires four physical conductors for the voice path, one pair for each direction (any additional wires required for signaling are not counted). In digital telephony, a transmission path that physically separates transmit and receive channels or timeslots. See also two-wire.
frame (data)

The basic data transmission unit used in bit-oriented protocols. A flag bit (also called a framing bit) at either end of the frame marks the beginning and end of an individual frame. Because a frame format is clearly defined, and conforms to a specific structure, network equipment can recognize the meaning and purpose of specific bits of data.
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. Each frame is 125 microseconds long.
gain

An amplitude scaling (in dB) applied to played speech after decompression or to recorded speech prior to compression.
ground

An electrical connection to earth or to a common conductor which is connected to earth.
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 HMIC, 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. See CompactPCI, CT_NETREF, CT_NETREF_1, CT_NETREF_2.
H-MVIP

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

H.100/MVIP Integrated Circuit; the single chip that offers full support for the H.100 bus within the MVIP architecture, providing access to all 4096 timeslots on H.100 and H.110 buses. The industry standard name for the HMIC is the Lucent T8100. See also H.100 bus, H.110 bus.
host

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.
in-band

Audio (voice) path of a telephone line interface.
line

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

A local connection between the input and output of a device. This is typically used for testing purposes.
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.
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.
multiplex

To transmit more than one signal or channel over a single physical circuit.
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. See also H.100 bus, H.110 bus.
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.
MVIP bus adapter

A hardware connector that attaches an MVIP-90 bus to an H.100 board (e.g., an AG Quad), which enables boards connected to the MVIP-90 bus to access the first 16 streams on the H.100 bus and boards connected to the H.100 bus to access streams of data on the MVIP-90 bus. See also MVIP bus, H.100 bus.
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 switch model

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

A network device with an MVIP switch that does not fully meet the MVIP standard or MVIP enhanced compliance standards.
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.
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.
non-blocking system

A switching system with enough switching capability to allow all possible sets of connections to be made. See also blocking system.
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.
ones density

The requirement for digital transmission lines in the PSTN that eight consecutive zeros cannot exist in a digital data transmission. On a T1 line, zero (0) means no voltage, no pulse. Since the bus clock is driven by the T1 line, too many consecutive zeroes can cause the clocking to fail. See also B8ZS.
out-of-band

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

In telephony, a repeated 8-bit sample applied to an output terminus of a switch block using messaging mode.
PCI

Peripheral Component Interconnect; a 32/64 bit local bus inside a PC. See also CompactPCI.
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.
PICMG

PCI Industrial Computer Manufacturers Group; an industry consortium which defined the CompactPCI standard, and other technical specifications such as hot swap. See also CompactPCI.
port

The meaning of this term can vary. Usually, it refers to a logical entity on a DSP board which can run telephony protocols, play and record voice files, or execute other DSP functions. It is typical to connect such a DSP port to a line interface or a trunk by using MVIP switching. This type of port generally corresponds to a CTA context in the ADI service.
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.
red alarm

One of the three alarms that indicate problems with T1 transmissions. A red alarm is generated for a locally detected failure, such as loss of synchronization for 2.5 seconds. See also AIS, blue alarm, yellow alarm.
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.
robbed-bit signaling

A signaling method that uses the least significant bit of each timeslot in every sixth frame to carry signaling information (on-hook, off-hook, etc.) for that voice channel. See also D4 framing.
runfile

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.
SEC8K

Secondary reference clock. The SEC8K clock typically drives the MC1_8K (8KREF) clock in an MC1 system, or is used as the backup reference clock on an MVIP-90 bus. See also clock master, clock slave.
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.
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).
slave

Bus clock slave; derives the clock signal from the bus clock, which is driven by the bus clock master. See also clock slave, clock master.
SRAM

Static Random Access Memory; RAM that retains its data without the refreshing required by DRAM. SRAM offers faster memory access time and is more expensive than DRAM. See also DRAM.
standard switching compliant

See MVIP Standard Switching Compliant device.
Static Random Access Memory

See SRAM.
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.
switch

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.
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 card

A circuit card (board) which contains an MVIP switch block. Since MVIP switching is distributed, systems may contain several switching cards. A given connection may involve more than one switch block on different switching cards.
switching compatible

See MVIP Switching Compatible device.
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.
T1 A standard for telephone transmission that multiplexes 24 digital voice channels on a single 1.544 Mbyte/s carrier.
task processor

A single DSP chip on a hardware 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). See also DRAM, NOCC, wink.
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 is defined in a data structure that contains fields specifying a bus, a stream, and a timeslot.
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.
tip

One conductor of a wire pair, designated by T; usually connected to the positive side of a line circuit. The other is called ring, or R. See also ring.
tri-stated

The condition of a logic circuit whose output is in the high impedance state. Most electronic logic circuits try to force their output voltage to be either high or low. Some circuits have a third option which is to present a high output impedance, effectively disconnecting them electrically from the output line. This allows multiple outputs to be safely connected to one line, forming a bus.
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.
trunk signaling

See signaling.
TSA

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

In analog telephony, a connection that requires only two physical conductors. See also four-wire.
voice-grade line

A local loop, or trunk; a 4 kHz channel having an audio bandpass of approximately 300 to 3200 Hz.
wink

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

One of the three alarms to indicate problems with T1 transmissions. A yellow alarm signal is sent back toward the source of a failed transmit circuit in a T1 transmission path. A yellow sends zeros in bit two of all timeslots. See also AIS, blue alarm, red alarm.
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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