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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. Also known as the telephone number.
- 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.
- 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.
- 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.
- 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.
- bus
- In the CT Access Switching service, specifies the interface point of the switch block. Devices can reside directly on the telephony bus. Devices can also reside on a board's local bus and may require a switch block to access the telephony bus. See also Switching service.
- clock
- A timing reference signal, e.g., on an MVIP bus.
- clock master
- The board that drives the clock signal for a system of boards connected by a bus cable. See also coprocessor.
- 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).
- CPE
- Customer Premise Equipment; customer-owned equipment connected to telephone company lines.
- cross-talk
- Undesired voice-band energy transfer from one circuit to another. Usually, the circuits are physically adjacent and analog.
- CT Access
- Natural MicroSystems' development environment for telephony applications.
- DID
- Direct Inward Dialing; an incoming telephone service which delivers the final portion of the called address to the CPE, thus allowing the caller to reach an individual extension of a PBX. See also CPE, PBX or PABX.
- digital
- Information in a discrete or quantized form. See also analog.
- Digital Signal Processor
- See DSP.
- DNIS
- Dialed Number Identification Service; a telephone company service that reports the number that the caller was trying to reach. to the called party. For example, a company with multiple 800 numbers would use this service to determine how to respond to an incoming call.
- 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.
- 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 removing a portion of the received signal determined to be echo by comparison with the output signal.
- encoding
- Any of several compression techniques for digitizing and compressing data.
- enhanced switching compliant
- See MVIP Enhanced Switching Compliant device.
- full-duplex
- Simultaneous two-way voice or two-way signal data transmission. See also half-duplex, simplex.
- 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 bus, host, MVIP-90, MVIP-95.
- half-duplex
- A circuit that can carry information in both directions, but can only use one direction at a time. See also full-duplex, simplex.
- Hertz (Hz)
- The unit of frequency. One hertz equals one cycle per second.
- 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.
- 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.
- Link Access Procedures on the D Channel (LAPD)
- CCITT recommendation Q.921; a protocol for communication at the data link layer.
- loop start (LS)
- A method of signaling an off-hook or a line seizure, where one end of the connection closes the loop circuit and the resulting current flow is detected by the switch at the other end.
- MC1 bus
- A SCSI-3 cable up to 15 meters long, used to connect MC1 boards in separate PC chassis so that an application can switch data between resources located in different host chassis.
- 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, MC1 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. See also 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 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.
- 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.
- network layer
- In the OSI protocol layering model, the network layer (layer 3) is the layer above the data link layer. Protocols for this layer describe methods for transferring information between computers. They also describe how data is routed within and between networks. One protocol used at this layer for ISDN applications is CCITT recommendation Q.931. See also Q.931.
- 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.
- 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.
- Open System Interconnect (OSI)
- A model for digital communication, developed by the International Organization for Standardization (ISO). The OSI model defines seven separate layers of communication. ISDN follows this protocol model to ensure end-to-end connectivity.
- OSI
- See Open System Interconnect (OSI).
- pattern
- In telephony, a repeated 8-bit sample applied to an output terminus of a switch block using messaging mode.
- PBX or PABX
- Private (Automatic) Branch telephone eXchange; a system providing local telephone switching in an office or building.
- PCI
- Peripheral Component Interconnect; a 32/64 bit local bus inside a PC.
- Point-to-Point Switching service
- CT Access service that provides an API for making switch connections between boards. The Point-to-Point Switching service enables an application to make switch connections without needing to specify stream and timeslots assignments.
- protocol (telephony)
- Defined procedure for call setup and call teardown.
- PSTN
- Public Switched Telephone Network; a public telephone network.
- Q.931
- CCITT recommendation Q.931 describes an ISDN protocol for the network layer (layer 3 in the OSI layering model). See also network layer, OSI.
- routing
- The process of finding an available path or sequence of paths that create a desired connection.
- 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).
- simplex
- A circuit which carries information in only one direction. See also full-duplex, half-duplex.
- 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 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, Point-to-Point Switching service.
- 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 DID, DNIS, loop start (LS), NOCC, wink.
- Transfer Control Protocol; a transport layer protocol that offers connection-oriented, reliable, stream service between two hosts. See also transport layer, UDP.
- 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.
- 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.
- transport layer
- In the OSI protocol layering model, the transport layer (layer 4) is the layer above the network layer. Protocols for this layer describe methods for maintaining reliable end-to-end communication across a network. See also network layer, OSI.
- Trunk Control Programs
- See TCP.
- UDP
- User Datagram Protocol; a connectionless, unreliable, transport network protocol for the exchange of replies between network hosts. See also TCP.
- wink
- An out-of-band signaling method that simulates an off-hook condition for a brief period.
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