28. What is a PBX?

A PBX is a Private Branch Exchange. A PBX is a small telephone switch owned
by a company or organization. Let's say your company has a thousand
employees. Without a PBX, you would need a thousand phone lines. However,
only 10% of your employees are talking on the phone at one time. What if
you had a computer that automatically found an outside line every time one
of your employees picked up the telephone. With this type of system, you
could get by with only paying for one hundred phone lines. This is a PBX.