User guide

Glossary

Multi-Tech Systems, Inc. MultiVOIP User Guide

PROM (Programmable Read Only Memory - pronounced "prom"): A permanent memory chip that can be programmed or

filled by the customer after by the manufacturer has set initial values. Contrast with ROM.

Protocol: 1. A set of semantic and syntactic rules that determines the behavior of functional units in achieving communication. 2. In

Open Systems Interconnection architecture, a set of semantic and syntactic rules that determine the behavior of entities in the same

layer in performing communication functions. 3. In SNA, the meanings of and the sequencing rules for requests and responses used

for managing the network, transferring data, and synchronizing the states of network components. 4. Synonymous with line control

discipline.

PSTN (Public Switched Telephone Network): A worldwide public voice phone network that is used as a telecommunications

medium for the transmission of voice, data and other information.

Public Data Network (PDN): A packet-switched network that is available to the public for individual ("subscriber") use. Typically,

controlled by a government or a national monopoly.

Public Switched Telephone Network (PSTN): The group of circuit-switching voice carriers, which are commonly used as analog

data communications services.

Pulse dialing: One of two methods of dialing a phone, usually associated with rotary-dial phones. Compare with "tone dialing".

Quality of Service (QoS): Guarantees network bandwidth and availability for applications.

Quantizing: The process of analog-to-digital conversion by assigning a range, from the contiguous analog values, to a discrete

number.

Random Access Memory (RAM): A computer's primary workspace. All data must be stored in RAM (even for a short while),

before software can use the processor to manipulate the data. Before a PC can do anything useful it must move programs from disk

to RAM. When you turn it off, all information in RAM is lost.

RAS Channel: An unreliable channel used to convey the Registration, Admissions and Status messages and bandwidth changes

between two H.323 entities.

Recognized Private Operating Agency (RPOA): A corporation, private or government-controlled, that provides telecommunica-

tions services. RPOAs, such as AT&T, participate as non-voting members in the CCITT.

Request for Comment (RFC): A set of papers in which Internet standards (published and proposed), along with generally-

accepted ideas, proposals, research results, etc. are published.

RJ-11: An industry standard interface used for connecting a phone to a modular wall outlet; comes in 4-and 6-wire packages.

RJ-45: An 8-wire modular connector for voice and data circuits.

Router: A device that connects two networks using the same networking protocol. It operates at the Network Layer (Layer 3) of the

OSI model for forwarding decisions.

Routing Information Protocol (RIP): A distance vector-based protocol that provides a measure of distance, or hops, from a

transmitting workstation to a receiving workstation.

RS-232-C: An EIA standard for a serial interface between computers and peripheral devices (modem, mouse, etc.). It uses a 25-pin

DB-25, or a 9-pin DB-9 connector. The RS-232 standard defines the purposes, electrical characteristics and timing of the signals for

each of the 25 lines.

RS-422: The EIA standard for a balanced interface with no accompanying physical connector. RS-422 products can use screw

terminals, DB-9, various DB-25, and DB-37 connectors.

RS-530: The EIA standard for the mechanical/electrical interface between DCEs and DTEs transmitting synchronous or asynchro-

nous serial binary data. RS-530 provides for high data rates with the same connector used for RS-232; however, it is incompatible

with RS-232.

Serial Port: The connector on a PC used to attach serial devices (those that need to receive data one bit after another), such as a

mouse, a printer or a modem. This consists of a 9- or 25-pin connector that sends data in sequence (bit by bit). Serial ports are

referred to as "COMx" ports, where x is 1 to 4 (i.e., COM1 through COM4). A serial port contains a conversion chip called a "UART"

which translates between internal parallel and external serial formats.

Service: The requirements offered by an RPOA to its customers to satisfy specific telecommunications needs.