A2-8 429850
Trend AuroraPlus User Guide
P
PABX Private Automatic Branch Exchange. Consists of a
number of ‘extension lines’ connected to a central
switching system. Users on these extensions can make
calls to each other. ‘Exchange lines’ connect the PABX
to the local public exchange, allowing the extension
users access to the Public Switched Telephone
Network (PSTN) or ISDN.
Packet switching A data transmission method that sends addressed
packets over physical and logical links. The physical
link is used only for the amount of time needed to
transmit the packet. Also called X.25.
PC Personal Computer.
PCM Pulse Code Modulation.
Physical Layer The lowest layer of the OSI model, which is
responsible for the electrical, mechanical and interface
aspects of transmitted data. Also known as Layer 1.
PMP Point-to-Multipoint.
Point-to- In Point-to-Multipoint mode (Layer 1) up to
Multipoint 8 terminals can be connected in parallel along the
bus. The length of the bus is limited to about
200m, depending on the cable. Multiple
TEIs can exist on Layer 2,
Point-to-Point In Point-to-Point mode one Terminal Equipment (TE)
is connected at the end of up to 1km of cable.
Only one TEI can exist on Layer 2.
Polarity The positive or negative state of an electrical
connection.
POTS (Plain Old Standard analogue telephone service.
Telephone Service)
App02.P65 01/05/01, 09:208
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