RADVISION术语表

Glossary (C)

# - A - B - C - D - E - F - G - H - I - J - K - L - M - N
O- P - Q - R - S - T - U - V - W - X - Y - Z

CABLE
The delivery of Internet service over cable infrastructure. The proliferation of cable modems, along with DSL technology, has ushered in the age of broadband Internet access via cable.

CAC (CONNECTION ADMISSION CONTROL)
The set of actions taken by the network during the call setup phase (or during the call re-negotiation phase) to establish whether a VC/VP connection can be accepted.

CALL CONTROL
Also called Call Processing. Refers to the signaling involved in setting up, monitoring, transferring and disconnecting (tearing down) a call.

CALL FALLBACK
Support for Call Fallback enables you to configure a Gatekeeper Forwarding policy to deal with cases, such as Gatekeeper failure to resolve a destination address in the IP network, lack of Gatekeeper bandwidth resources, or unsuccessful call setup to the destination endpoint due to network failure.

CALL SIGNALING ROUTING
Two alternative modes for routing the Call Setup (Q.931) and Control (H.245) channels. Routed Mode routes the Call Setup and Control channel through the Gatekeeper.
See also Routed Mode, Direct Mode, Q.931 + H.245 Routed Mode

CALL WAITING
A telephone network feature. If a calling party places a call to a called party which is otherwise engaged, and the called party has the call waiting feature enabled, the called party is able to suspend the current telephone call and switch to the new incoming call, and can then negotiate with the new or the current caller an appropriate time to ring back if the message is important, or to quickly handle a separate incoming call.

CAPABILITY
Because terminals and servers are complex, and support multiple protocols, multiple codecs, and many optional features, calls need to communicate their capabilities so that negotiation and connection are successful to complete the call.

CASCADING
The MCU allows you to combine two or more conferences resulting in a larger conference with many more participants. This is called Cascading. Cascading creates a distributed environment that helps reduce drain on network resources.

CCCP (CENTRALIZED CONFERENCING CONTROL PROTOCOL)
A protocol belonging to the IETF related to SIP and IMS. Responsible for the transport of the conference control commands from the user agent to the (conferencing) application server

CCXML (CALL CONTROL EXTENSIBLE MARKUP LANGUAGE)
An XML standard designed to provide telephony support to VoiceXML. CCXML is designed to inform the voice browser how to handle the telephony control of the voice channel.

CDMA (CODE DIVISION MULTIPLE ACCESS)
A form of multiplexing and a method of multiple access that does not divide up the channel by time or frequency. CDMA also refers to digital cellular telephony systems that make use of this multiple access scheme, such as those pioneered by Qualcomm, or WCDMA.

CDMA2000
A family of third-generation (3G) mobile telecommunications standards that use CDMA, a multiple access scheme for digital radio, to send voice, data, and signaling data (such as a dialed telephone number) between mobile phones and cell sites. It is the second generation of CDMA digital cellular.

CDR (CALL DETAIL RECORD)
Information in a simple text format that can be used as input to third party billing programs or other software for billing purposes.

CENTRALIZED MCU CONFERENCES
In a centralized topology, the Multipoint Controller and Media Processor unit components of the MCU work together to manage conference signaling and to perform media processing for all connected terminals. The MCU can handle multiple conferences simultaneously.
See also MCU, Cascading, Clustered MCUs

CIF (COMMON INTERMEDIATE FORMAT)
A standard video format used in video conferencing. CIF requires four times the bandwidth of QCIF (176 by 144 pixels).

CIPHER
An algorithm for performing encryption (and the reverse, decryption) — a series of well-defined steps that can be followed as a procedure.

CLI (CALLER LINE ID)
The calling party’s number, and in some places, the calling party's name, sent to the called party's telephone equipment during the ringing signal, or when the call is being set up, but before the call is answered.

CLIP (CALLING LINE IDENTIFICATION PRESENTATION)
The presentation of a number being identified by Caller ID (CLI) The opposite of CLIR.

CLIR (CALLING LINE IDENTIFICATION RESTRICTION)
The blocking of a number from being identified by Caller ID.

CLUSTERED MCUs
The Multipoint Controller (MC) and Media Processor (MP) unit components of the MCU operate independently. The MCU can be set up in a clustered layout to use a single MCU to control several units configured to operate only as MP units performing media processing. MCUs configured as MP-only units have their MC component disabled. The controlling MCU unit also makes use of the local MP component.

CODEC (CODER/DE CODER)
Hardware or software that converts sound, speech or video signals from analog to digital code, and vice versa.

COMPRESSION
A technique for reducing the bandwidth or bit rate required to encode a block of information so that it occupies less space on a transmission channel or storage device.

CONFERENCE HUNTING
The purpose of Conference Hunting is to maintain conferences and ignore Line Hunting where necessary.

CONFERENCING SERVICE
The conferencing service is a mechanism supported on the MCU which defines the qualities, capabilities and management policies of a conference.

CONFIDENTIALITY
Defined by the International Standards Organization (ISO) as "ensuring that information is accessible only to those authorized to have access." Confidentiality is the cornerstone of information security.

CONNECTIONLESS SERVICE
Network service that does not require a session connection between senders and receivers. Senders simply start sending packets to the destination. Useful for periodic burst transfers. A connectionless network provides minimal services.

CONNECTION-ORIENTED SERVICE
Connection-oriented service requires a session connection (analogous to a phone call) to be established before data can be sent. This method is often called a "reliable" network service. It can guarantee that data will arrive in the same order. Connection-oriented services set up virtual links between end systems through a network.

CONTACT CENTER
A call center generally receives and handles customer calls. When the call center handles not only a voice channel but also a chat or e-mail or video channel, it is referred to as contact center.

CONTENT PROVIDER
A company that provides services to subscribers or network operators. These services include shopping, Web surfing, chat rooms, gaming, accessing data, such as music and books through a server, and more.

CONTINUOUS PRESENCE
Allows you to view multiple participants in one screen at the same time. Incoming participant images are combined into a video image layout set according to the policies of the conferencing service. The range of video layouts available depends on the type of media processing supported.

CONVERSATIONAL SERVICE
A service that provides two-way, interactive, real-time, end-to- end information transfer.

COPS (COMMON OPEN POLICY SERVICE)
A protocol used for exchanging network policy information between a Policy Decision Point (PDP) in a network and the Policy Enforcement Points (PEPs). On WCDMA networks, the GPRS Gateway Serving Node (GGSN) is the PEP as part of overall QoS system.

CORBA (COMMON OBJECT REQUEST BROKER ARCHITECTURE)
A standard for software components that defines APIs, communication protocols, and object/service information models to enable heterogeneous applications written in various languages running on various platforms to interoperate. Provides platform and location transparency for sharing well-defined objects across a distributed computing platform.

cPCI (COMPACT PCI)
A 3U or 6U Eurocard-based industrial computer, where all boards are connected via a passive PCI backplane. The connectors and the electrical rules allow for 8 boards in a PCI segment. Multiple segments are allowed with bridges.

CPCP (CONFERENCE POLICY CONTROL PROTOCOL)
A client-server protocol that can be used by users to manipulate the rules associated with the conference.

CRC (CYCLIC REDUNDANCY CHECK)
A type of hash function used to produce a checksum — a small, fixed number of bits — against a block of data, such as a packet of network traffic.

CS (CIRCUIT SWITCHED)
A networking technology that provides a temporary but dedicated connection between two stations regardless of the number of switching devices through which data is routed. Analog circuit switching (FDM) has been replaced by digital circuit switching (TDM). The digital technology still maintains the connection until one speaker hangs up.

CSCF (CALL/SESSION CONTROL FUNCTION)
A key IMS element that makes session or call control and routing decisions in the IMS network; CSCF uses IMS SIP signaling to control sessions.
See also P-CSCF and S-CSCF

CSICS (CIRCUIT SWITCHED IMS COMBINATIONAL SERVICES)
Services for the transitional phase of early IMS deployment that leverage existing circuit-switched infrastructure to deliver real- time media, combined with ease of advanced and easy to deploy IMS services, such as presence, IM and more.

CUG (CLOSED USER GROUP)
Used to define a virtual private network on a public network.