A phone system has a control unit or a "brain" that is
basically a very complex telephone. The control unit answers calls and
routes the calls to the appropriate place depending on how it is set up.
The "telephones" sometimes called "voice terminals" on a phone system can
not do anything by themselves and receive all of the power, data and sound
from the main brain. Typically a phone system has the ability to access
many phone lines and allows the "voice terminals" to call each other. Most
phone systems also have a voice mail unit attached or built in that allows
automated answering of calls, call routing, and taking messages.
A business phone is NOT a telephone. It looks like a phone and
plugs in like a phone, but it works completely different! Try plugging the cable
from your computer monitor (the one that plugs into the video port) into a cable tv
line... it won't work, and you may even break your computer monitor. The same thing
goes with business phones. Unfortunately the same plugs were used on regular phones and
business phones but that is where the similarities end.
Try to think of your business phone as a computer monitor and the KSU
(control box) as the computer. Your computer probably only has one monitor but your phone
system can have many business phones. Each phone can get different information but it is
all controlled at the KSU. When a call comes into the KSU, the KSU acts like a multi-line
phone. The programming in the KSU will determine which business phone will react when a
call comes in.
When a call comes in, the KSU will see the line ring, look at it's
programming instructions and then use it's own special signal to tell the phone(s)
to ring. A regular phone rings when it receives a 90v AC 30hz pulse from the
phone company, a business phone rings when it receives a certain set of 1's and
0's from the KSU (usually 5v DC) Guess what happens when a business phone,
designed for 5 volts, gets a 90v AC 30hz pulse?
When you press any button on a business telephone it sends a signal to the
KSU. The KSU then looks at its programming to see what that button should do. If an LED is
lit up on your phone, the KSU has sent a signal to the phone telling it to light that LED.
Another words, your business phone is basically nothing but a speaker, a handset, and a
bunch of buttons and lights. It has no brain and will not function at all on
it's own.
There are exceptions to all of this and it depends a lot on which phone
system you have. However, most systems work in at least a similar way to the above
statements. Also, some systems can handle single line devices in special ports. They use
their own power converter or power supply to send a 90v AC signal that makes a regular
phone ring.
