Often when a business is looking for a commercial intercom, what they really need is a telephone system along with an external
paging system. The telephone system allows employees to either call specific
areas of the building, or with an external paging amplifier and speakers, they
can page the entire building. A door phone can be added to the telephone system
to enable visitors to an external door of the building to press a button to call
someone inside, and that inside person could press a button to unlock the door.
However, there are times where a telephone system is not
what is wanted. Telephone systems are expensive and the labor required to run
the wires throughout the building is just as expensive.
If all that is wanted is the door phone application, then
you can get intercoms that have a single outdoor monitor along with a
desktop or wall mounted indoor station. Then there is only one wire to run
between the door and the inside station. Or you can also choose wireless
intercoms for this application.
Sometimes there are just a few areas of the business where
some form of communication is needed and there is no desire to run wires to
them. That’s where wireless commercial intercoms are needed.
One problem with wireless intercoms in many commercial
intercom applications is that the environment is more challenging for the
wireless equipment. In manufacturing companies there is a lot of equipment that
may produce interference. The building construction often consists of metal
framed walls and more electrical wiring to handle office equipment. Many
commercial buildings are made of concrete walls and floors. These conditions
will greatly reduce the range of a wireless intercom.
So when you look for wireless commercial intercom systems
you want to make sure a system has a much longer range than you actually need.
The longer range the intercom system has, the more power it has to overcome the
obstacles in a commercial environment.
These next sections review some of your options for a
wireless intercom system.
Intercoms in the 900 MHz frequency really have limited use
in commercial applications. The range is usually too limited.
If your building is not large or made out of concrete and
metal, then a 900MHz intercom may work perfectly OK for you. Many small
businesses use them.
only 900MHz system currently on the market is the
WireFree 900MHz Wireless
. As the name says, it transmits wirelessly in the 900MHz
frequency range. This is the only true wireless system on the market. It is not
the only one that transmits wirelessly through the airwaves, but it is the only
one that is battery powered. It is not even plugged in to an AC outlet unless
you choose to purchase the optional power adapter.
The WireFree system is unique in that it has multiple
low-cost components that no other wireless intercom system has. It has portable
intercom units that sit on the surface of a desk, table, or countertop. There
are two styles of this unit with one being called the WireFree Extreme Range
system. It transmits and receives the same distance as the non-extreme range
unit. Both have a maximum range of 1000 feet, but you are more likely to get in
the 300 foot range depending on environment. Both units have the same feature
set. They just have different physical appearance and price.
The WireFree system has a water-resistant outdoor doorbell
intercom that can be used at your front door to talk to people there. The nice
thing about this unit is once the people at your door press the button, they can
talk hands free.
There is also a water-resistant outdoor intercom that can
be used in any outdoor installation. This intercom requires button presses for
every transmission. You can hang it on the wall or also put rubber feet on this
unit and use it inside if you want. The nice part is that it only has one large
button which makes it easy to use.
The WireFree system also has a flush mount intercom that
can make your installation more custom looking. It requires cutting a hole in
your wall, but it is battery powered too so no wiring is required. The battery
life in all the WireFree units is 1 to 2 years so they don’t require a lot of
The WireFree system has a Monitor and VOX feature that not
all wireless intercoms have. Monitor is like a baby monitor mode. The difference
is that it does not continuously monitor. Its microphone only turns on when it
detects sound that’s loud enough to turn on the microphone. There are three
different sensitivity settings to trigger the microphone, but even at its most
sensitive setting, it won’t work well for faint voices more than a couple of
feet from the microphone. The downside of using the Monitor mode for some
applications is that it sounds a tone on the receiving side every time the
microphone is activated. If you were using this to monitor a room where sound
occurs frequently, this would get irritating pretty fast.
If you put a WireFree unit in VOX mode, whenever someone
from another unit calls the unit in VOX mode, they can respond hands free
without pressing the Talk button. One problem that is shared with two-way radios
that have VOX is that there is a slight delay in transmission while the VOX
circuitry turns on the transmit microphone. Experienced radio operators know how
to overcome this by repeating the first word or two, but for the average person,
this delay is a little frustrating.
One unique feature of the WireFree system is its ability to
do private conversations. Units have to be “taught” to talk with each other.
Once this is done, even if your neighbors have the same unit, they can’t listen
or talk to yours. Also when you broadcast a page to all units, the WireFree
system will set up a private conversation between the broadcaster and the person
responding so all other units won’t hear the conversation.
Yet another wireless intercom system is not so much of a
system from one manufacturer as it is a compilation of wireless intercoms and
two-way radios. This “
MURS system” is based on compatible products in the MURS radio
frequency. As talked about above, MURS stands for Multi-Use Radio Service and is
a two-way radio service consisting of five frequencies in the VHF (Very High
Frequency) spectrum. Unlike most frequencies in the VHF range, MURS does not
require an FCC license to operate.
Even though there are only 5 channels, each channel can
choose between one of 38 “quiet codes” or sub-channels to keep you from hearing
conversations of other users on that channel. You will only hear conversations
from radios set to the same channel and quiet code as your radio. In most areas
the MURS frequencies are very lightly used so you won’t find a lot of
competition for the airwaves.
The biggest benefit of MURS is the range it offers. Some
manufacturers claim a range of four miles. Of course this range is a line of
sight with no obstructions between intercoms. Range can even be increased with
these intercoms by adding an external high-gain antenna on top of your business,
or even car if you use a unit there.
What’s nice about MURS is that you can get handheld two-way
radios, commercial-duty base station and outdoor intercoms/callboxes, and even
motion detectors that transmit a verbal alert message to other MURS devices. For
business, industrial, or commercial applications a MURS system excels since it
can overcome a lot of interference and obstacles these applications present.
If you need a wireless PA (public address) system, there is
a wireless PA device that works with all the MURS radios. For retail business
that service customers directly, there is even a wireless MURS device that
enables customers to press a button and call for assistance via a transmitted
Since any manufacturer can create a MURS wireless device,
choosing a MURS system keeps you from being locked in to whatever products a
particular manufacturer chooses to offer.
If you are willing to get a license for your radio, then
you can use either the UHF or VHF business bands. You can get most of the same
devices as you can in the MURS range above.
you need a way for clients, students, employees, or anyone else to communicate
with you from distant areas of your campus or
property, a callbox or call box is
one way to do it. A call box is a box made of metal or fiberglass that contains
electronic circuitry that enables someone to press a button or pick up a handset
and call a central location for assistance. Some callboxes also allow calling a
portable radio so that assistance can be mobile.
There are two main types of callbox units available, wired
and wireless. A wired callbox involves running a cable to it from the central
location. This section is about the other kind, the
The benefit of a wireless callbox is that you save money by
not having to do trenching and running expensive cable to the unit. You also
don’t have to pay any air-time or telephone service fees with these wireless
systems. As mentioned, another benefit is that since the unit is wireless,
people monitoring the units can carry handheld radios that communicate with the
callbox. That allows your monitoring people to be mobile.
The range of these units is several miles, which can be
extended by adding an external antenna. Some units can use radio repeaters to
extend this range even more.
If you have existing two-way business radios, you’ll want a
system that can integrate with them. Some callboxes can be programmed to be
compatible with virtually any brand of VHF or UHF business band radio.
can get call boxes that require an FCC license, or you can get units that are
certified for use on special FCC License-Free MURS Business Frequencies. If you
choose a licensed version, the license is usually not too difficult or expensive
One problem you may have in placing a call box is the lack
of available power. You’ll want to choose a system that lets you use battery or
AC power. You can also get units that have optional solar power so that they can
run for several days on a single day of sunshine.
If you need to remotely control gates, magnetic door locks,
or barrier arms from your portable 2-way radio or desktop base station intercom,
then select a unit that has this capability. With this ability you can let
someone in a gate or door when they call you. There are units that also let you
turn on a strobe light at the callbox location to help draw attention to it.
Another useful feature is the ability for call boxes to
store a voice message that is played when someone presses its button. This could
be a message that gives the caller specific instructions on what to do. These
units can also send a second and different voice message alert to the monitoring
central location or portable radios. This message could give the callboxes
location or it could be an emergency message of some type.
If you have several callboxes in use and you need to know
the location of the unit calling in, then you can get a call box that transmits
a unique numeric identifier to a radio that has the ability to decode this
identifier. This is like having a telephone with Caller ID capability.
By adding a motion detector or some other detection device,
you can be alerted when that detection device is activated. Some callboxes will
send either a tone alert or a custom voice alert when the detection sensor
status changes. If this voice message is not immediately answered, the alert
message is resent multiple times.
If you are running your system on battery power, you need a
unit that has battery conservation mode. In this mode, only the absolute
necessities for operation are powered, and the unit can not accept calls to it;
it can only make calls. You can attach an external sensor to automatically put
the unit into full power mode when someone is detected near the box. This will
allow you to make a call to it.
Other useful features:
- If you want to listen to what’s happening around the
call box, then you’ll need a unit that can be paged so you can use the
callbox microphone to monitor the sound around it.
- A low battery alert or external power fail tone is
sent to the monitoring portable radio or base intercom.
- A paging feature allows selective calling of
individual boxes or a group of callboxes simultaneously.
- The busy channel feature prevents someone from
transmitting if someone else is using the radio channel.
- Wireless callboxes have fast installation since no
wiring is required.
- Entry keypad with built-in relay lets people enter a
code at the call box to open a gate or door. Remote opening of the gate by
monitoring personnel can still happen also.
These callboxes are being used for applications like
parking lots, college campuses, airports, hospitals, construction sites,
manufacturing facilities, resorts, hotels, farms, warehouses, delivery docks,
campgrounds, gated facilities, or anywhere people may need assistance. So by
using call boxes, you can put clear wireless voice communication anywhere you
need it, quickly, without expensive trenching and monthly air-time fees.