英文關鍵字
abstract
analog
and
automatic
background
booth
box
branch
busy
cable
camera
cctv
complicated
concept
confused
control
danger
design
difficult
electrical
engineering
exchange
failure
fiber
hard
house
hub
inside
lan
landline
line
mixed
old
open
optic
pabx
pattern
pbx
phone
private
problem
public
road
security
solutions
street
system
telecom
telecommunication
telephone
terrible
texture
traditional
wire
wires