NEC ElectraElite 48 System Hardware Manual page 431

Issue 6
A - 2
Abbreviations
CRC Cyclic Redundancy Check
CRC is a common method to establish that the data is
correctly received in data communications. This process
checks the integrity of a block of data. A CRC character is
generated at the transmission end. Its value depends on
the hexadecimal value of the number of ones in the data
block. The transmitting device calculates the value and
appends it to the data block. The receiving end makes a
similar calculation and compares its results with the added
character. If there is a difference, the recipient requests
retransmission.
DN Directory Number
Unique number (phone number) assigned to each
telephone or data terminal.
ISDN Integrated Services Digital Network
An international plan to migrate the public switched network
to the universal implementation of standard digital
technology.
LSA Line Synchronization Alarm Detection
A T1
synchronization occurs when a given digital channel (time
slot) at the receiving end is aligned with the corresponding
channel (time slot) of the transmitting end as it occurs in the
received signal. Usually extra bits (frame synchronization
bits) are inserted at regular intervals to indicate the
beginning of a frame and for use in frame synchronization.
LCR Least Cost Routing
A feature that automatically chooses the lowest cost phone
line to the destination.
OOF Out-of-Frame Condition
During T1 transmission, an Out-of-Frame error occurs
when two or more of four consecutive framing bits are in
error. When this condition exists for more than 2.5 seconds
a Red alarm is sent by the OOF detecting unit. Equipment
that receives this Red alarm responds with a Yellow alarm.
OPX Off-Premise Extension
A telephone that is located in a different office or building
from the mail phone system. The OPX is connected by a
dedicated telephone line. This extension has all abilities of
the mail phone system.
Definition
trunk looses frame
Electra Elite
synchronization. Frame
Glossary of Abbreviations