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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.
- address In telephony, the number dialed by a calling party which identifies the party called. Commonly called the phone number.
- ADI Service Service providing all AG device-level functionality for CT Access. 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.
- 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.
- 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.
- 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.
- clock A timing reference signal, e.g., on an MVIP bus.
- clock master The board that sources the clocks in an MVIP system.
- 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).
- crosstalk Undesired voice-band energy transfer from one circuit to another (usually physically adjacent).
- CT Access Natural MicroSystems' development environment for telephony applications.
- digital Information in a discrete or quantized form. See also analog.
- Digital Signal Processor
See DSP.
- 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 Nomenclature for the individual unidirectional bit streams on the MVIP bus. By convention, they are paired up (DSiX, DSoX) to form the 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 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.
- Dynamic Random Access Memory
See DRAM.
- 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.
- enhanced switching compliant
See MVIP Enhanced Switching Compliant.
- full duplex Simultaneous two-way voice and two-way signal data transmission. See also half-duplex and simplex.
- ground An electrical connection to earth or to a common conductor which is connected to earth.
- 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.
- Hz See Hertz.
- ISA Industry Standard Architecture; the de-facto bus card standard in the IBM-PC compatible world. Also known as the PC/AT bus.
- line A logical telephone connection on which a call can take place.
- 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.
- multiplexing The transmission of two or more channels on 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.
- 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.
- NMS Natural MicroSystems Corporation.
- 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.
- 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.
- pattern An 8 bit sample that is sent out of an output terminus or into an input terminus of a switch block.
- protocol (telephony) Defined procedure for call setup and call teardown.
- PSTN Public Switched Telephone Network; a public telephone network.
- routing The process of finding an available path or sequence of paths that create a desired connection.
- 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.
- 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-domain 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.
- 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).
- 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.
- time division multiplexing
See TDM.
- timeslot Specifies a particular sub-division of a TDM bus stream. Timeslots number from zero (0) to n where n is stream dependent.
- Trunk Control Programs
See TCP.
- wink An out-of-band signaling method that simulates an off-hook condition for a brief period.
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