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Appendix A
Glossary
- A B C D bits
- The four signaling bits used in channel associated signaling. The value that these bits take determines or indicates the state of the telephone channel. Many protocols do not use all four bits. Usually, only the A and B bits are used in North America, but all four are used in Europe.
- A bit
- See also A B C D bits.
- 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.
- 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.
- 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.
- B bit
- See A B C D bits.
- blocking system
- A switching system with limited switching capability cannot make all possible sets of connections. Under some circumstances, a connection cannot be made and the call is blocked. See also non-blocking system.
- bus (telephony)
- A physical system which permits the interchange of data. A telephony bus has three basic elements: lines for the data, bit synchronization (clocks), and frame synchronization (frame strobe). Most telephony buses also have a network reference - an 8 kHz timekeeper. See also MVIP.
- bus (field)
- In CT Access, bus is a field in the terminus structure that specifies the interface point of the switch block. See also switching, terminus.
- 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.
- C bit
- See A B C D bits.
- clock master
- The board that drives the clock signal for a system of boards connected by a bus cable.
- 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).
- CT Access
- Natural MicroSystems' development environment for telephony applications.
- D bit
- See A B C D bits.
- digital
- Information in a discrete or quantized form. See also analog.
- Digital Signal Processor
- See DSP.
- DLL
- Dynamic Link Library; a library of software object modules that can be loaded and accessed on demand.
- 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.
- enhanced switching compliant
- See MVIP Enhanced Switching Compliant device.
- events
- In CT Access, data structures that contain notification of certain conditions or state changes. Events can be sent from the hardware or from another software module to the application program. All events are represented as C data structures. The event structure contains information about the specific event, including a timestamp, associated CTA context, specific data, error codes, or reason codes. For example, when a voice play operation completes, a completion event is returned to the application.
- FPGA
- Field Programmable Gate Array; for QX 2000 boards, a circuit which provides internal glue logic.
- FSK
- Frequency Shift Keying; a type of analog modem signal that uses two frequencies to send ones and zeroes.
- full-duplex
- Simultaneous two-way voice or two-way signal data transmission.
- 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.
- line
- A logical telephone connection on which a call can take place.
- 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.
- 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.
- 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. An interoperable subset of the H.100 bus standard.
- MVIP bus
- A high-speed, multiplexed digital telephony "highway" which allows boards to share data, signaling information, and switching information. See also bus.
- MVIP bus adapter
- A hardware connector that attaches an MVIP-90 bus to an H.100 board (e.g., an AG Quad), which enables boards connected to the MVIP-90 bus to access the first 16 streams on the H.100 bus and boards connected to the H.100 bus to access streams of data on the MVIP-90 bus. See also MVIP bus.
- MVIP Enhanced Switching Compliant device
- A network device with a switch implementing all possible connections of the MVIP switch model.
- MVIP switch model
- An abstract representation of the logical switching capabilities that can be located on one physical network interface device.
- network
- In telephony, short for the telephone switching network. See also PSTN.
- In information technology, a series of points or nodes interconnected by communication paths. Networks can interconnect with other networks and contain subnetworks.
- NMS
- Natural MicroSystems Corporation.
- NMS ADPCM
- A form of ADPCM that requires less processing power than the CCITT standard and provides equivalent voice quality. See also ADPCM, PCM.
- 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 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.
- on-hook
- The inactive state of a customer telephone circuit. The term is derived from old telephone sets where the receiver, when not in use, was placed on a hook attached to a switch. The opposite condition is off-hook.
- pattern
- In telephony, a repeated 8-bit sample applied to an output terminus of a switch block using messaging mode.
- PCI
- Peripheral Component Interconnect; a 32/64 bit local bus inside a PC.
- PCM
- Pulse Code Modulation; a digital scheme for transmitting analog data. The signals in PCM are converted into binary data, which is then transmitted digitally.
- port
- A point of connection, such as:
- A logical channel in a communications system, usually associated
with physical hardware resources.
- A point of connectivity between a computer and anything else,
such as telephone trunks, human operators, voice processors, or fax
terminals.
- In Internet transport protocol, refers to the abstraction used to
distinguish between multiple simultaneous connections to a single
destination host. A port is a transport layer demultiplexing value.
Each TCP/IP application has a unique port number associated with
it.
- Refers to a logical entity on a DSP board which can run telephony
protocols, play and record voice files, or execute other DSP
functions. It is typical to connect such a DSP port to a line interface
or a trunk by using MVIP switching. This type of port generally
corresponds to a CTA context in the ADI service.
- Refers to telephone connections supported by a board (for
example, the AG 2000 board is an 8-port board).
- protocol (telephony)
- Defined procedure for call setup and call teardown.
- protocol-independent
- Consistent for all available protocols.
- PSTN
- Public Switched Telephone Network; a public telephone network.
- Pulse Code Modulation
- See PCM.
- QSLAC
- Quad Subscriber Line Audio Circuit; four-port audio circuit which can be programmed to comply with country-specific line parameters. See also port.
- QX
- The NMS board family which features low port telephony and voice processing hardware.
- qxload
- Utility program which reads a configuration file and uses it to load and configure the QX 2000 hardware.
- ring
- The alerting signal to the subscriber or terminal equipment; also the name for one conductor of a wire pair, designated by R. The other is called tip, or T. See also tip.
- 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.
- service managers
- Service managers implement CT Access services, communicate with the dispatcher, and adhere to CT Access standards. They are implemented as dynamic link libraries (DLLs) in Windows NT and as shared libraries in UNIX, and are linked to the application.
- 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).
- 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 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 MVIP.
- 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.
- 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 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.
- tip
- One conductor of a wire pair, designated by T; usually connected to the positive side of a line circuit. The other is called ring, or R. See also ring.
- TSA
- Telephony Services Architecture; the NMS model of managing telephony and media functionality in computer systems.
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