Glossary and Abbreviations

555-230-024GL-36 Issue 5 January 1998

node
A switching or control point for a network. Nodes are eithe r tandem (they receiv e signal s and pa ss
them on) or terminal (they originate or terminate a transmission path).
Nonfacility-associated signaling (NFAS)
A method that allows multiple T1 and/or E1 facilities to share a single D-channel to form an
ISDN-PRI. If D-channel backup is not used, one facility is configured with a D-channel, and the
other facilities that share the D-channel are config ured without D-ch annels. If D-ch annel backup is
used, two facilities are configured to have D-channels (one D-channel on each facility), and the
other facilities that share the D-channels are configured without D-channels.
NPA
Numbering-plan area
NPE
Network processing element
NQC
Number of queued calls
NSE
Night-service extension
NSU
Network sharing unit
null modem cable
Special wiring of an RS-232-C cable such that a computer can talk to another computer (or to a
printer) without a modem.
NXX
Public-network office code
O
OAOperator assisted
occurrence
See appearance.
OCM
Outbound Call Management
offered load
The traffic that would be generated by all the requests for service occurring within a monitored
interval, usually one hour.
ONS
On-premises station
OPS
Off-premises station
OPX
Off-premises extension