Licence-Free ≠ Free to Use: PMR, ISM, CB and Mesh Rules

Licence-free does not mean rule-free. PMR446, CB, ISM, SRD, FRS, MURS, Meshtastic and MeshCore all live inside legal frameworks — even when no individual licence is required.

There is a magical moment in every radio hobbyist’s life when they discover the words “licence-free”.

No exam. No callsign. No yearly bill. No paperwork.

Clearly, this must mean the band is an RF paradise where every handheld, homebrew node, external antenna, amplifier, gateway, digipeater, repeater and “just testing” experiment is welcome.

Sadly, no.

Licence-free does not mean free to use however you like.

It usually means that you do not need an individual licence only if you follow the exact service rules, equipment rules, power limits, antenna limits, duty-cycle limits, channel plans and usage restrictions.

The spectrum is not “free”. It is pre-authorised under conditions.

And those conditions matter.

The first trap: “The frequency is free”

A frequency is not a service.

A number on a display is not permission.

For example, 446 MHz means very different things depending on where you are and what service you are using.

In Europe and the UK, PMR446 is a specific licence-exempt personal mobile radio service around 446 MHz.

In the United States, 446 MHz sits inside the amateur 70 cm band, while the US licence-free “walkie-talkie” equivalent is usually FRS around 462 and 467 MHz.

Same general UHF neighbourhood.

Completely different legal house.

That is why “my radio can tune there” is not the same as “I may transmit there”.

A wide-open VFO is not a passport.

PMR446 is not “any UHF radio on 446 MHz”

PMR446 is one of the most misunderstood licence-free services in Europe and the UK.

It is not just “446 MHz”. It is a defined service with defined equipment.

PMR446 equipment is intended to be hand portable, short-range, peer-to-peer and normally uses an integral antenna.

It is not intended as a rooftop base station, repeater system, internet gateway, permanent infrastructure node or “I found this old ham radio and programmed channel 1” solution.

Example: “I programmed my ham handheld to PMR446 channel 1”

Still not automatically legal.

Even if you set the radio to low power and behave politely, the radio itself may not meet the PMR446 service requirements.

The regulator does not grade your intentions.

It checks the rules.

Example: “I built a PMR446 gateway on my roof”

That is where the licence-free fairy usually leaves the room.

PMR446 is not intended for fixed infrastructure, repeaters or base-station-style gateways.

The fact that it works technically does not mean it is permitted legally.

Example: “I brought US FRS radios to Europe”

No.

American FRS radios are not PMR446 radios with an American accent.

They use different frequencies, different service rules and different equipment authorisation.

PMR446 is great. It is simple, cheap, useful and legal when used correctly.

But it is not a sandbox for any programmable UHF radio that happens to land on 446 MHz.

ISM and SRD: the “free band” with footnotes

The words ISM band often create another dangerous misunderstanding.

People hear “ISM” and think “anything goes”.

In reality, most radio communication devices used in these areas are operating under short-range device rules in Europe and the UK, or Part 15 rules in the United States.

Those rules specify power, bandwidth, duty cycle, antenna gain, channel access, permitted use and unwanted emission limits.

In Europe, SRD rules are harmonised to a degree, but national implementation still matters.

In other words, “Europe” is not one giant universal LoRa playground.

In the UK, licence-exempt short-range devices must meet the relevant UK interface requirements.

In the US, Part 15 devices may operate without an individual licence only if they comply with Part 15 conditions.

Example: “My LoRa node is licence-free, so I can set maximum power”

No.

In parts of Europe, duty cycle is a real limit, not a suggestion from a shy standards committee.

Regional firmware settings, such as EU_868, US_915 or EU_433, exist for a reason.

Example: “I bought a 915 MHz mesh device; I’ll use it in Europe”

Careful.

915 MHz is common in some regions, including the United States, but that does not make it the default legal choice for Europe.

Europe commonly uses 868 MHz and 433 MHz ranges for certain SRD applications, each with their own limits and restrictions.

Example: “The band is quiet, so I can use it”

No.

Silence is not allocation.

A frequency can be quiet because nobody nearby is using it, because you cannot hear the protected user, or because legal users are intermittent.

“I heard nothing” is good operating practice.

It is not a licence.

The device matters: AliExpress is not a regulator

Another common trap is the idea that a device becomes legal because it is easy to buy.

A radio board from AliExpress, eBay, Amazon, a hobby shop or a random “LoRa / PMR / 433 / 868 / 915 MHz” listing does not automatically become legal in Europe, the UK or the US.

Online checkout is not type approval.

“It was shipped to me” is not a spectrum licence.

And the most dangerous sentence in radio compliance is probably:

“But it has CE on the chip.”

That may mean very little for the finished radio product.

CE on a chip is not CE for the product

In Europe, radio equipment placed on the market must meet the applicable requirements for safety, electromagnetic compatibility and efficient use of spectrum.

CE marking is supposed to apply to the product as placed on the market, with the required conformity assessment, technical documentation and Declaration of Conformity.

A CE mark on a chip, module or reference board does not automatically make the complete device compliant.

Once you add a different antenna, enclosure, battery charger, switching power supply, USB interface, display, amplifier, firmware setting, cable or PCB layout, you may have created a different radio product.

Example: “The LoRa module has CE, so my Meshtastic box is CE”

Not automatically.

The complete box may still need to be assessed as a finished radio device.

The chip may be fine.

The module may be fine.

The final product may still be an RF goblin.

Example: “The board says 868 MHz, so it is legal in Europe”

No.

It must use the correct frequency range, power level, duty cycle or channel access method, bandwidth, antenna gain and emission limits for the country and application.

A board capable of 868 MHz is not automatically an EU-compliant SRD product.

It is just a board with ambitions.

Example: “It has a CE logo on the PCB”

That might refer to the module, not the finished product.

It might refer to some other part of the device.

It might be incorrectly applied.

It might be decorative optimism.

What matters is whether the finished product has the correct conformity assessment, technical documentation, instructions, restrictions of use and actual measured compliance.

Licence-free equipment is often approved as a system

Some licence-free services are not only about frequency and power.

They also define the type of equipment.

PMR446 is a good example.

PMR446 is not simply “anything that transmits on 446 MHz at half a watt”.

It is intended as hand-portable, short-range, peer-to-peer equipment, typically with an integral antenna and without base-station or repeater use.

FRS in the United States is another example.

It has specific channels, power limits and equipment requirements, including limits on antenna configuration and transmitter capability.

A wideband handheld with a removable antenna is not magically transformed into an FRS radio because you programmed an FRS channel into it.

This is why many licence-free devices should be understood as a complete approved system:

• the transmitter;
• the firmware;
• the channel plan;
• the power setting;
• the antenna;
• the enclosure;
• the filtering;
• the duty cycle or transmit timeout;
• and the intended use.

Change one of those, and you may no longer be using the device in the way it was approved.

Filtering: the part nobody sees until they interfere with someone

Cheap experimenter boards can be fun.

They can also be electrically rude.

A transmitter does not only produce the frequency printed on the display.

It can also produce harmonics, spurious emissions, broadband noise, synthesizer rubbish, switching-regulator noise and out-of-band energy.

Good radio equipment uses suitable design and filtering to keep that unwanted energy below the legal limits.

Example: “My 433 MHz board transmits on 433 MHz”

Maybe.

But what else does it transmit?

A poorly filtered transmitter may also radiate harmonics or garbage elsewhere.

Your receiver might not show it, your SDR might not notice it, and your antenna analyser will not give confession.

The spectrum analyser is where the little sins appear.

Example: “I added an amplifier to my licence-free node”

Excellent.

You may now have amplified not only the wanted signal, but also the unwanted emissions.

Congratulations: your noise has more confidence.

Example: “I changed the antenna because the stock one was bad”

Maybe you improved range.

Maybe you changed ERP or EIRP.

Maybe you broke the approval conditions.

Maybe the device was compliant only with the supplied integral antenna.

The antenna is not always an innocent accessory.

In many licence-free systems, it is part of the approved radio system.

Meshtastic and MeshCore: the mesh does not legalise the radio

Meshtastic, MeshCore and similar projects are fantastic.

They make radio approachable, useful and fun.

But the software does not magically legalise the hardware, antenna, power level, frequency, duty cycle or filtering.

The region setting is not decoration.

The antenna is not legally invisible.

The amplifier is not forgiven because the project is open source.

The duty cycle does not disappear because the payload is small.

Example: “I enabled a public mesh, so it is community service”

Nice sentiment.

Still not a legal category.

Your node must comply with the radio rules for the country and band.

Public benefit does not automatically increase your permitted ERP, remove duty-cycle limits or bless your rooftop antenna.

Example: “I am a licensed ham, so I’ll just run the mesh under amateur radio rules”

That may be possible in some places and on some amateur bands, but then you are no longer playing the same game.

You are using amateur radio rules.

That means amateur service purpose, amateur identification, no commercial traffic, no encryption where prohibited and compliance with the relevant amateur regulations.

So yes, a ham licence gives you privileges.

It does not give you diplomatic immunity.

CB radio: not a place for your HF ham rig to “visit”

CB is another classic example of “licence-free but not rule-free”.

In Europe and the UK, CB is channelised and has defined equipment and power limits.

In the United States, CB is regulated under its own personal radio service rules.

It is not simply “somewhere around 27 MHz”.

Example: “My amateur HF transceiver can transmit on 27 MHz, so I can use it on CB”

No.

That is like saying your car can physically drive on a railway track, therefore it is a train.

CB requires CB-compliant equipment and CB rules.

An amateur radio that has been opened up for wide transmit is not automatically legal CB equipment.

Example: “I’ll add a small amplifier; everyone does it”

The amplifier fairy is not recognised by CEPT, Ofcom or the FCC.

CB power limits are part of the service conditions.

Example: “I found a quiet frequency just above or below CB”

Congratulations, you may have discovered freebanding, not legality.

CB is channelised.

The empty-looking space nearby may belong to another service, another country’s allocation or someone you cannot hear.

US FRS, GMRS and MURS: similar radios, different rulebooks

The United States has its own personal radio services.

They are not interchangeable with PMR446.

FRS uses UHF channels around 462 and 467 MHz and is licence-free only when used with compliant FRS equipment under the applicable rules.

GMRS shares some channel space with FRS but is a licensed service.

“It looks like FRS” does not mean “it is licence-free FRS with more watts”.

MURS is another US personal radio service using VHF channels around 151 and 154 MHz, again with its own rules and equipment requirements.

Example: “I’ll use my ham handheld on FRS because it can tune the frequency”

No.

FRS is not “any radio on an FRS frequency”.

It is a defined service with specific transmitter requirements.

Example: “I have a GMRS radio; I’ll use it licence-free because the channel is shared with FRS”

Not necessarily.

Shared channel space does not erase service identity.

The legal question is not only “what frequency?” but also “what service, what radio, what power, what antenna and what licence status?”

The ham-radio trap: knowledge can make you overconfident

Many radio amateurs understand propagation, antennas, SWR, modulation, repeaters and RF safety.

That is good.

But sometimes that knowledge creates a dangerous illusion:

“I understand radio, therefore I can decide what is reasonable.”

Regulators do not usually write rules in the form of “use common sense and be a nice person”.

They write tables.

Depressing tables.

Tables with bandwidths, ERP, EIRP, duty cycles, channel centres, occupied bandwidth, antenna restrictions, emission masks and equipment standards.

The amateur licence is powerful inside the amateur service.

It does not authorise you to ignore PMR446 equipment requirements, CB equipment requirements, FRS transmitter certification, Part 15 limits, SRD duty cycles or national band plans.

A ham radio on CB is not CB.

A ham radio on PMR446 is not PMR446.

A ham radio on FRS is not FRS.

It is often just a very capable radio doing something it is not authorised to do.

The simple checklist before transmitting

Before using any “licence-free” radio system, ask:

• What country am I in? Europe, the UK and the US do not use identical rules.
• What service am I using? PMR446, CB, FRS, MURS, Part 15, SRD/ISM, amateur radio or something else?
• Is my equipment compliant for that service? Not just tunable. Not just low power. Actually compliant.
• Are the antenna rules respected? Integral antenna, detachable antenna, gain limits, ERP and EIRP all matter.
• Are power, bandwidth, channels, duty cycle and timeout limits respected? Especially for LoRa and mesh systems.
• Is the finished product compliant? Not only the chip, module or reference board.
• Is there proper filtering? The wanted signal is only part of the story.
• Am I using infrastructure, gateways, repeaters, store-and-forward or encryption? Those can change the legal situation quickly.
• Am I assuming my ham licence covers it? It probably does not, unless you are actually operating under amateur rules on an amateur allocation.

Final thought

Licence-free radio is wonderful.

PMR446, CB, FRS, MURS, LoRa, Meshtastic, MeshCore and other short-range systems give ordinary people access to practical radio communication without the barrier of individual licensing.

But licence-free is not law-free.

It means the licence is replaced by conditions.

Break the conditions, and you are not “using licence-free radio” anymore.

You are just transmitting without the permission you thought you had.

Or, in more traditional radio language:

Read the manual. Check the band plan. Respect the service. And remember: the VFO may turn, but the law does not turn with it.

A €12 board with a mystery CE mark is not a European harmonised standard.

It is a €12 board with a mystery CE mark.

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