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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.
- 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.
- 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.
- bit An acronym for binary digit; the smallest piece of information; a specification of one of two possible alternatives: zero or one.
- 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.
- broadcasting Sending the same information to two or more parties.
- 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.
- CCITT Comite Consultatif Internationale de Telegraphique et Telephonique; an international organization, based in Geneva, that recommends standard practices for communications. Now publishing under the name of its parent organization - ITU.
- CEPT Conference of European Postal and Telecommunications administrations; a European telephony standards committee.
- 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.
- Codec A device that converts digital signals to analog, and vice versa.
- 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).
- CSA Canadian Standards Association; CSA certification is required for most electrical equipment used in Canada.
- CT Access Natural MicroSystems' development environment for telephony applications.
- 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.
- DOC Department of Communications; the Canadian government agency that regulates communications and the use of the electromagnetic spectrum.
- 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®.
- Dynamic Random Access Memory
See DRAM.
- enhanced switching compliant
See MVIP Enhanced Switching Compliant.
- FCC Federal Communications Commission; the US government agency that regulates and monitors interstate communications and the use of the electromagnetic spectrum.
- full duplex Simultaneous two-way voice and two-way signal data transmission. See also half-duplex and simplex.
- 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-MVIP The hardware standard for MVIP-95.
- half-duplex A circuit that can carry information in both directions, but only in one direction at a time. See also full duplex and simplex.
- Hertz (Hz) The unit of frequency. One hertz equals one cycle per second.
- host The PC CPU where the host application runs.
- hybrid A circuit that interfaces a bidirectional transmission channel to separate receive and transmit channels.
- Hz See Hertz.
- in-band Audio (voice) path of a telephone line interface.
- in-band signaling Signaling where information is carried as audio signals that are transmitted in the voice path. Touch-Tone® dialing is a familiar example. See also out-of-band signaling.
- International Telecommunications Union
See ITU.
- ISA Industry Standard Architecture; the de-facto bus card standard in the IBM-PC compatible world. Also known as the PC/AT bus.
- ITU International Telecommunications Union; an international standards body for telecommunications.
- KB Kilobyte, 1024 bytes.
- Kbps Kilobits per second, 1000 bits per second.
- KBps Kilobytes per second, 1000 bytes per second.
- line A logical telephone connection on which a call can take place.
- loopback Connecting the input and outputs of a device locally. This is typically used for testing purposes.
- 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.
- Mbps Megabits per second, 1,000,000 bits per second.
- megahertz A unit or measure (MHz), used to quantify band and bandwidth, that denotes one million Hertz (cycles per second).
- 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 on a PC.
- MVIP bus A high-speed, multiplexed digital telephony "highway" which allows boards to share data, signaling information, and switching information.
- 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 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.
- MHz See megahertz.
- nail-up To make a permanent assignment, as in "nailing-up" a connection.
- network In telephony, short for the telephone switching network.
- 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 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.
- out-of-band Information carried outside of the audio or voice channel.
- out-of-band signaling Refers to signaling methods where signaling information is carried by a separate channel. In addition to technical advantages, out-of-band signaling helps prevent unauthorized tampering with the network. See also in-band signaling.
- 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.
- port An external connection between the MVIP bus and anything else, including telephone trunks, human operators, voice processors, FAX processors, etc.
- POTS Plain Old Telephone Service, single line residential phone service.
- 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.
- 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).
- simplex A circuit which carries information in only one direction.
- 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-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 card A circuit card containing an MVIP switch block. Since MVIP switching is distributed, systems may contain several switching cards. A desired connection may involve more than one switch block on different switching cards.
- 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.
- 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).
- Telco The telephone company, the common carrier providing access to the telephone network.
- 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.
- timeslot Specifies a particular 64kbit/second sub-division of a TDM bus stream. Timeslots number from zero (0) to n where n is stream dependent.
- trunk A transmission channel connecting two switching machines.
- Trunk Control Program
See TCP.
- trunk signaling See signaling.
- TSA Telephony Services Architecture; the NMS model of managing telephony and media functionality in computer systems.
- wink An out-of-band signaling method that simulates an off-hook condition for a brief period.
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