Nortel Passport 4400, Using Manual, Page: 132 / 144

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NPI
Numbering Plan Indicator. The part of a given data network address that
defines the numbering plan to which it belongs. Examples of numbering plans
defined by ITU-T are X.121 and E.164.
null modem
A special cable that enables you to connect two computing devices together
through their serial ports without the need for a modem.
numbering plan
See NPI.
off-hook
A line condition that exists when an operational, active telephone handset is
removed from its cradle.
ones Density
A requirement in T1 and E1 transmissions, that the bit stream includes a
minimum percentage of ones (1s). Since the receiving end cannot track on 0s,
proper ones density ensures reliable clock recovery.
on-hook
A line condition that exists when an operational, active telephone handset is
resting in its cradle.
OSPF
Open Shortest Path First. An IP routing protocol, classified as an Interior
Gateway Protocol (IGP). This means that it distributes routing information
between routers belonging to a single Autonomous System (AS).
packet
A group of bits, including data and control signals, arranged in a specific
format and transmitted as a whole.
PANL
Passport Access Network Link. A Passport link support service designed to
communicate with Passport 4400 access units. PANL includes proprietary
protocol elements derived from ITU-T X.36 (Frame Relay) and signaling
protocols (Q.922 and Q.933) to enhance the treatment of voice traffic over