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Appendix A
Glossary
- A bit One of four bits used to carry channel associated signaling on digital trunks and on MVIP signaling streams. The others are called the B, C and D bits. Many protocols do not use all four bits. Usually, only the A and B bits are used in North America, while all four are used in Europe.
- 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.
- ABCD bits The signaling bits used in channel associated signaling. The value that these bits take determines or indicates the state of the telephone channel. See also CAS.
- analog Information represented by a continuous and smoothly varying signal amplitude or frequency. Opposite of digital.
- bit An acronym for binary digit; the smallest piece of information; a specification of one of two possible alternatives: zero or one.
- broadcasting Sending the same information to two or more parties.
- bus In the MVIP-95 standard, 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.
- CAS Channel Associated Signaling; a signaling method where signalling information is provided on a line-by-line or channel-by-channel basis. In-band signaling is a type of Channel-Associated Signaling. See also Common Channel Signaling.
- CEPT Conference of European Postal and Telecommunications administrations; a European telephony standards committee.
- CEPT E1 A standard used in Europe for digital telephone carriers. CEPT E1 is similar to T1 but operates at 2.048 Mbps and has 32 channels instead of T1's 24. Also referred to as E1.
- 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.
- Common Channel Signaling
A signaling method where signaling information is provided for a number of channels in data-packet form sent over a separate link. This separate link is usually another channel of the same digital trunk, called a D channel in ISDN service.
- connection (MVIP) Connects an input terminus to an output terminus. The input and output terminuses can have the same or different buses and streams.
- digital Information in a discrete or quantized form. Opposite of analog.
- Digital Signal Processor
See DSP.
- 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 Touch-Tone®.
- E1 See CEPT E1.
- enhanced switching compliant
See MVIP Enhanced Switching Compliant.
- Fax Facsimile machines for sending and receiving images and written material. Almost all fax machines today use the CCITT Group 3 protocol. A higher performance protocol, CCITT Group 4, is available for ISDN.
- forward Used to explain a typical full duplex connection between a DSP resource and a network interface. See also reverse.
- frame (T1/E1) A portion of a PCM data stream that contains one binary data word, typically 8-bits, for each unidirectional channel. A frame usually will also contain control and synchronization bits and is 125 msec long.
- frame (data) The basic data transmission unit used in bit-oriented protocols. A group of data bits arranged in a specific format with a flag at either end to indicate the beginning and end. Because frame format is clearly defined, network equipment can recognize the meaning and purpose of specific bits of data.
- full duplex Simultaneous two-way voice and two-way signal data transmission. See also half-duplex and simplex.
- ground start A method of signaling between two machines where one machine grounds one side of the line and the other machine detects the presence of ground.
- 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.
- HDLC High Level Data Link Control; a link layer protocol for point-to-point and multi-port communications. In HDLC, control information is placed in specific positions. In addition, the bit patterns used to encode control information differ substantially from those used to represent data.
- Hertz (Hz) The unit of frequency. One hertz equals one cycle per second.
- High Level Data Link Control
See HDLC.
- host The PC CPU where the host application runs.
- 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.
- ISA Industry Standard Architecture; the de-facto bus card standard in the IBM-PC compatible world. Also known as the PC/AT bus.
- ISDN Integrated Services Data Network; a standard for providing voice and data telephone service with all digital transmission and message based signaling.
- 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.
- 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.
- 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-90 switch model.
- MVIP Standard Switching Compliant Device
A network device with a switch that does not implement the full MVIP-90 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-90 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.
- NMS Natural MicroSystems Corporation.
- 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.
- operator workstation A type of network interface which connects to operator headsets.
- 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.
- port An external connection between the MVIP bus and anything else, including telephone trunks, human operators, voice processors, fax processors.
- POTS Plain Old Telephone Service, single line residential phone service.
- protocol (telephony) Defined procedure for call setup and call teardown.
- PSTN Public Switched Telephone Network; a public telephone network.
- pulse dialing The method used on rotary-dial telephones to signal a telephone number for automatic switching. Each digit is encoded as a series of one to ten pulses, which are brief interruptions of current flow on the line. See also DTMF.
- resource boards In an MVIP system, boards that perform processing functions, such as voice processing, voice recognition, fax sending and receiving, but do not have switching capabilities.
- In MVIP-95, these boards transmit on even numbered streams and receive on odd numbered streams.
- reverse Used to explain a network interface to network interface full duplex connection. See also forward.
- 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.
- standard switching compliant
See MVIP Standard Switching Compliant Device.
- 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 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.
- T1 A standard for telephone transmission that multiplexes 24 digital voice channels on a single 1.544 Mbps carrier.
- T1 trunk A digital trunk used for channel associated signaling in the US.
- 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.
- terminus In theMVIP-95 standard, a single access point to a switch block input or switch block output. A terminus contains a bus, a stream, and a timeslot.
- time division multiplexing
See TDM.
- timeslot Specifies a particular 64 kbit/second subdivision of a TDM bus stream. Timeslots number from zero (0) to n where n is stream dependent.
- tri-stated The condition of a logic circuit whose output is in the high impedance state. Most electronic logic circuits try to force their output voltage to be either high or low. Some circuits have a third option which is to present a high output impedance, effectively disconnecting them electrically from the output line. This allows multiple outputs to be safely connected to one line, forming a bus.
- trunk A transmission channel connecting two switching machines.
- Trunk Control Programs
See TCP.
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