- C -

C bit

See A B C D bits.

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 ADSI, ANI.

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).

CED

CallED tone; the 3-second 2100 Hz tone that a called fax terminal places on the line to indicate that the called station is a fax terminal. See also CIG, CNG, T.30.

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.

chained layers

In the OSI layering model, the chained layers are defined to be the lowest three layers: the physical layer, the data link layer and the network layer. See also ISDN.

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.

channelizer

An entity on the AG ISDN protocol stack between the ACU and the ISDN TCP. It routes D channel information between the lower ISDN layers through the state machine implemented by the ISDN TCP to the application. Without a channelizer, one application performs call control for all channels. Using a channelizer enables a separate application to perform call control for each channel. See also ACU, D channel, TCP.

CIG

CallInG subscriber identification; used in fax polling by the calling fax terminal to identify itself. The CIG is defined by ITU T.30 as the calling station's international telephone number. It can contain up to 20 characters. See also CED, CNG, T.30.

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 gateway application, packet-switched network, 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.

cleardown tone

An in-band tone from the CO or switch indicating that the remote party has hung up. See also CO.

client

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.

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.

CNG

CalliNG tone; the 0.5 second, 1100 Hz tone placed on the line every 3 seconds until CED is received. The CNG tone indicates a fax terminal is calling. See also CED, CIG, T.30.

CO

Central Office; the location of the public network switch.

codec

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

combined signaling link set

Two or more link sets terminated at one end on an end signaling point (SSP or SCP) and at the other end on a mated pair of STPs containing equivalent routing capability. Since, under normal conditions, each STP in the pair has the same routing capability, traffic to any particular destination from the originating signaling point is load shared across both STPs via the combined link set. See also SCP, SSP, STP.

command queue

In the Diva SDK, the input queue of mail commands for a Diva VSP from the host.

commands

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.

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 hot swap, PCI, PICMG.

compatibility level

Used for runtime interoperability checking between a target software module and a caller of that module.

compelled sequence

An exchange of in-band signaling during call setup, where each party waits for receipt acknowledgment from the other party before sending the next signal.

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.

component

Used in TCAP, a particular request (for example, translating an 800 number) or a response (for example, providing a translated number). Several components may be contained in the same TCAP message. See also TCAP.

conference

A group of callers connected together in the same telephone call.

conference bridge

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

conference seat

One of several available parties (callers) who can participate simultaneously in a telephone conversation.

connection

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 the CT Access Switching service, a path between an input terminus and an output terminus. The input and output terminuses can refer to the same or different buses and streams. See also terminus.

In the CT Access Point-to-Point Switching service, a connection point which can support one talker (input source) and multiple listeners (output destinations). See also listener(s), Point-to-Point Switching service, talker.

connection handle

Handle returned when a switch connection is successfully opened in the Point-to-Point Switching service.

connection ID

In ISDN, a handle to a call on a B channel. The connection ID is assigned to outbound calls by the application, and to inbound calls by the AG ISDN protocol stack. It is used to identify the call in all communications between the ACU and the application. See also ACU, B channel.

connection object

In the CT Access Point-to-Point Switching service, an internal data structure, returned when a switch connection is successfully opened, that records the state of the connection. See also Point-to-Point Switching service.

connectionless

Refers to network service that depends on exchanging requests and replies between connected hosts rather than on the connections between hosts. See also circuit-switched network, packet-switched network.

continuous word speech recognition

Speech recognition that can accept naturally spoken utterances without requiring explicit pauses between utterances.

contributing source (CSR)

A source of a stream of RTP packets that has contributed to the combined stream produced by an RTP mixer. The mixer inserts a list of the SSRC identifiers of the sources that contributed to the generation of a particular packet into the RTP header of that packet. This list is called the CSRC list. For example, in audio conferencing, a mixer indicates all the talkers whose speech was combined to produce the outgoing packet, which enables the receiver to indicate the current talker, even though all the audio packets contain the same SSRC identifier (of the mixer). See also mixer, RTP.

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).

CP

Communications Processor; refers to any of the TX series boards.

CPCON

A host-based utility that provides a user interface to the Kernel. This utility presents a line-oriented operator console to any CP. See also CP, KERNEL.

CPE

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

CPI

Computer to PBX Interface; a hardware/software interface that provides connectivity between a switching network and a host computer.

cross-talk

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

CSA

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

CSI

Called Subscriber Identification; an optional frame used by the called fax terminal to deliver its international telephone number. The frame can contain up to 20 characters. See also Group 3 fax, T.30.

CSU

Channel Service Unit; a device connecting customer T1 equipment and a network line. See also T1.

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.

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.

ctahd

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

ctaqueuehd

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

ctdaemon

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.

current gain

The relative scaling of electrical currents, often expressed as a simple ratio. See also gain.

current message

In the CT Access Voice Message service, a message or a list of messages becomes current (for operations such as pausing, resuming, or repositioning) when it is actively being played by the application. It is associated with a CTA context handle and a current position.

current position

In the CT Access Voice Message service, the current offset (in milliseconds) into the current message. See also current message.