License-free usage in U.K. requires that radios have a fixed antenna and our radios have a removable antenna.  So to use our wireless intercoms, you will be required to get a license. See the Business Band link below for more information.

License Free
http://radiotechnology.suite101.com/article.cfm/pmr446_cb_2way_radio_in_the_uk

Business Band
http://www.ofcom.org.uk/licensing/applications08/changes/

Another factor is the range you need to cover. How far apart are the intercoms going to be? But it’s more than just distance. Building construction can greatly reduce the distance a wireless intercom will communicate. A wood-framed building with siding will reduce the range less than a concrete or brick building.

Depending on where you put the wireless exterior intercom you may also have to worry about vandalism. You need to ask yourself whether someone will attempt to steal or destroy the unit. If so, then you need a unit built to resist vandalism.

At IntercomsOnline.com we have several wireless exterior intercom systems that can handle being used outdoors. See the links below:

Light-duty, short-range intercom:

WireFree Outdoor 900MHz Intercom

Light-duty, short-range hands free doorbell:

WireFree Wireless 900MHz Doorbell and Intercom

Light-duty, long-range intercom/callbox:

MURS Basic Commercial Callbox

Heavy-duty, long-range, vandal-proof intercom/callbox:

MURS Callbox XT Outdoor Intercom

Heavy-duty, long-range, vandal-proof intercom/callbox with gate opener:

MURS Callbox XT Outdoor Intercom with Gate Relay

We had a childcare center in New Mexico meet this requirement with our MURS wireless intercom system. They placed our MURS Outdoor Callbox Wireless Intercom on the playground. Then inside they place a combination of MURS Commercial Intercoms and MURS 4-Mile Range Intercoms.

They could have also added a portable handheld two-way radio to the system so the office manager could always be in contact with someone on the playground.

All these units are available at www.intercomsonline.com .

We have a couple of ways we handle this application. Both applications require installing a wireless intercom on both the quiet and noisy sides.

In really noisy environments we recommend installing the MURS Wireless PA system. he MURS Wireless PA (Public Address) is a radio receiver that allows you to use your base station intercom or mobile 2-way radio to deliver voice messages directly to an attached PA horn speaker up to 2 miles away. While this PA system can’t be used for two way communication, it will get the attention of someone in a noisy environment so they can stop what they are doing and go to a wireless intercom to talk. In this application either the MURS Multi-Mile Intercom or the MURS Commercial Intercom will work on either side. You can mix these two together since they will talk to each other.

You would put the MURS Wireless PA on a different channel than you use to communicate between the quiet and noisy areas. So to contact someone, you switch to the PA channel, speak your message, and then switch back to the communication channel to talk to them.

In marginally noisy environments we recommend the MURS Commercial Intercom on the noisy side. You can add an external speaker to this unit that will increase the volume a little. If you have a powered amplifier of some sort laying around, you could also feed the output jack on the MURS Commercial Intercom into your amplifier to increase the volume of the signal. You can use the cheaper MURS 4-Mile Range Intercom on the quiet side.

The WireFree system has a VOX mode that enables you to press the Talk button on the inside intercom and then the person on the other side of the bulletproof glass can speak without pressing a button. They just simply speak and you hear them (there is a two second delay before the microphone is activated). You can interrupt them at any time by pressing your Talk button so you remain in control of the conversation. They can speak for up to 15 seconds before the microphone cuts off again. You can simply press the Talk button again for another 15 seconds (both units must also be set in Conference mode as well).

There is a Monitor mode on the WireFree system, but the microphone will be activated every time a noise occurs on the other side of the glass. This will produce a tone on the inside intercom when ever the microphone is activated. That could get a little irritating and you probably don’t want to hear every little noise. Although the sensitivity of the Monitor mode is adjustable so you could make it less sensitive so it doesn’t pick up every noise.

Our WireFree Intercom System has four channels and each room could be set to a different channel. If you have a main intercom, it can be set to monitor all four channels so the rooms can call it. When the main intercom responds, a private conversation occurs. If the main room needs to call one of the rooms, you would press the Channel button to match the channel of that room. At the end of the call, you would put the intercom back in the monitor all channels mode by pressing the Channel button until all four channel lights are on.

The MURS 4-mile range intercom has 5 channels, but it does not have the ability to monitor all 5 channels at once.

The MURS Multi-Mile Intercom will penetrate the concrete walls. The MURS Callbox XT Outdoor Intercom is a waterproof wireless intercom that works with the inside base station intercoms. It is waterproof and in a hardened case.

The MURS Basic Commercial Callbox could also be used, but the antenna must be wrapped with a waterproof tape per manufacturer’s instructions. The tape is available at building supply stores.