Filter
Top Products
91
Glossary
Pulse dialing: One of two methods of dialing a telephone, usually associated with rotary-dial phones. Compare with "tone dialing".
Q
Quantizing: The process of analog-to- digital conversion by assigning a range, from the contiguous analog values, to a discrete
number.
R
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.
Rate Enforcement: The concept in frame relay where frames sent faster than the CIR are to be carried only if the bandwidth is
available, otherwise they are to be discarded. (The frame relay network assumes that anything exceeding the CIR is of low priority.)
Rate enforcement makes sure that the network will not get so congested that it isn't able to meet the agreed on CIR
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.
Red Alarm: A T1 error condition generated when a local failure (e.g., loss of synchronization) iexists for 2.5 seconds, causing a Carrier
Group Alarm (CGA). See also "Blue Alarm" and "Yellow Alarm".
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.
Ring Down Box: A device that emulates a CO by generating POTS calls for testing and product demos.
Ring Down Circuit: A tie line connecting phones where picking up one phone automatically rings another phone. A feature used for
emergencies to alert the person at the other phone of the incoming call.
RJ-11: An industry standard interface used for connecting a telephone to a modular wall outlet; comes in 4-and 6-wire packages.
RJ-45: An 8-wire modular connector for voice and data circuits.
Robbed Bit Signaling: The popular T1 signaling mechanism where the A and B bits are sent by each side of the T1 termination and are
"buried" in the voice data of each voice channel in the T1 circuit. Since the bits are "robbed" infrequently, voice quality is remains
relatively uncompromised. See "bit robbing".
The robbed-bit signaling technique is used in D4 channel banks to convey signaling information. The eighth (least significant) bit of each
of the 24 8-bit time slots is "robbed" every sixth frame to convey voice-related signaling information such as on-hook, off-hook, etc., for
each channel.
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 transmit-
ting workstation to a receiving workstation.
RS232-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 asynchronous
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.
S
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.
Severely Errored Seconds (SES): Refers to a typical T1 error event where an error burst occurs (a short term, high bit-error rate that
is self-clearing). Per the ITU-T (CCITT) G.821: any second in which the BER is less than 1x10
-3
.