Legal bands
902 to 928 MHz ISM: Legal and Unlicensed
Quick answer
The 902 to 928 MHz ISM band is legal and unlicensed for wireless microphones in the United States. It is 26 MHz wide and outside the television spectrum entirely, so no auction can strand it, but it is shared with cordless phones, smart meters and industrial telemetry.
This band is the quiet alternative almost nobody considers. It sits above the television spectrum, so nothing that happens to TV channels can take it away, and it is unlicensed, so there is no application and no fee. The catch is the company it keeps: 902 to 928 MHz is an industrial, scientific and medical band, which in plain terms means it is a free for all. Whether it works in your building depends on what else in your building is already using it. Count your channels first in the wireless microphone channel calculator, then compare this band against the UHF working band on equal terms.
On this page
Who else is in 902 to 928 MHz
The honest way to assess this band is to walk around the building and count the things already transmitting in it. In an older church the answer may be almost nothing. In a building with a modern utility meter, a wireless alarm system and a couple of cordless phones, the answer is quite a lot.
The 26 MHz of ISM spectrum here is shared with cordless phones, utility metering and building telemetry, none of which will move for you.
| Occupant | Where it is in a church | How much it matters |
|---|---|---|
| Cordless telephones | Church office, nursery, kitchen | Older handsets are the single biggest cause of trouble here |
| Utility smart meters | Electric and water service entry | Short bursts, low duty cycle, usually tolerable |
| Wireless alarm and sensor networks | Door contacts, thermostats, leak sensors | Low duty cycle but constant across the week |
| Long range sensor radios | Parking lot gates, remote buildings, signage | Occasional, and very hard to trace when it does bite |
| Wireless microphones | Your platform | Legal, unlicensed, and last in the queue |
Unlicensed means you must accept interference from everything above and stop causing any you produce. Nothing in this table is obliged to move for a church service.
How many channels fit
Twenty-six megahertz sounds generous next to a 2 MHz duplex gap, but frequency hopping systems use the band differently from fixed frequency ones and manufacturers set their own limits. The realistic planning number for a church is four to eight channels, and the lower end of that is the number to budget against.
Expect four to eight channels at 902 to 928 MHz, similar to 2.4 GHz but with better range and different neighbours.
| Band | Width | Realistic channels | Typical indoor range | Main competitor for the spectrum |
|---|---|---|---|---|
| 902 to 928 MHz ISM | 26 MHz | 4 to 8 | 150 to 250 feet | Cordless phones and metering |
| 1920 to 1930 MHz DECT | 10 MHz | 4 to 8 | 100 to 150 feet | Cordless phone base stations |
| 2.4 GHz ISM | 83.5 MHz | 4 to 8 | About 100 feet | Every Wi-Fi access point in the building |
| 5.8 GHz ISM | 150 MHz | 6 to 10 | 75 to 125 feet | Wi-Fi on the 5 GHz band |
Channel counts are practical expectations from published manufacturer figures rather than theoretical maxima, and they fall fast when the band is busy. Ranges assume a clear path and no body between transmitter and receiver.
When 900 MHz is the right choice
Three situations make this band genuinely attractive. The first is a church in a market where every television channel below 608 MHz is occupied, which happens near major metropolitan areas and near the border. The second is a building where the Wi-Fi is heavily used and the 2.4 GHz band is already congested, since 900 MHz sidesteps that fight entirely. The third is a portable church that moves between rented rooms, because a band with no coordination requirement is one less thing to do at seven in the morning in an unfamiliar gymnasium.
Against that, product choice is narrow. Far fewer systems are sold for 900 MHz than for UHF or 2.4 GHz, which means fewer capsule options, fewer rack mount receivers and a thinner spares market. Search what is currently available with a 900 MHz wireless microphone system before assuming your preferred capsule exists on the platform.
The mainstream alternatives, honestly compared
For most churches the shortlist is still UHF for channel count and 2.4 GHz for simplicity. Reach for 900 MHz when a specific problem points at it, not as a default.
Shure BLX24/SM58 Wireless Microphone System - 14-Hour Battery Life, 300 ft Range, UHF
$389.00 Specs and sizingUHF in the 470 to 608 MHz band, with up to twelve compatible channels per band. If your market has open television channels, this is more capacity than any licence-free band will give you.
Best for: Churches with clear TV spectrum and four or more channels
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Shure GLXD24+/SM58 Digital Wireless Vocal System - Z3 Band
$659.00 Specs and sizingDual band 2.4 and 5.8 GHz with automatic frequency management, which solves the same crowded-UHF problem 900 MHz is usually reached for, with a far wider product range behind it.
Best for: Small to mid-size rooms with nobody to coordinate frequencies
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Audio-Technica ATW-1102 Wireless Handheld Microphone System
$349.95 Specs and sizingA 2.4 GHz digital system with automatic frequency selection at entry price. Not the same band, but the same argument: outside television spectrum and untouched by any auction.
Best for: One or two channels in a small building
Check price on AmazonWhat usually goes wrong at 900 MHz
The failure is almost always a neighbour rather than the system. A cordless phone in the church office handled once a week can sit on a microphone frequency for the length of a call, and because the phone is two rooms away nobody connects the two events. Utility meters and alarm sensors transmit in short bursts, which produces brief clicks rather than dropouts and is maddening to diagnose.
The diagnostic habit that works is boring and effective: when a fault appears, write down the time. Three weeks of times will show whether the problem is the same point in the service, which points at something you are doing, or scattered, which points at a neighbour. Then walk the building with the receiver signal meter and find what else is transmitting. The same discipline is set out in the church AV maintenance schedule.
How we chose
We did not test these products in person and we never claim to. Picks are researched from manufacturer specification sheets and operator manuals, FCC rules where spectrum is involved, published standards, warranty terms, and the recurring themes in verified owner reviews. Every pick is matched to a real room size, seat count or input list rather than to a price bracket, and it is placed in the tier where its capability actually belongs. Where a product is wrong for most churches we say so on the page.
Sources
- FCC guidance for wireless microphone users
- FCC Part 15 rules for unlicensed operation in the ISM bands
- Published manufacturer specifications for licence-free wireless microphone platforms
Frequently asked questions
Are 900 MHz wireless microphones legal in the United States?
Yes. The 902 to 928 MHz ISM band is unlicensed and open to wireless microphones under Part 15. It sits above the television spectrum, so the 600 MHz incentive auction did not touch it and no future television auction can. The trade for that stability is that you share the band with cordless phones, utility meters and building telemetry.
How many channels can I run at 902 to 928 MHz?
Plan for four to eight, and budget against the lower end. The band is 26 MHz wide, but frequency hopping systems use that width differently from fixed frequency systems and each manufacturer sets its own compatible channel limit. If you need more than eight channels, the UHF television band is the only realistic place to find them.
Is 900 MHz better than 2.4 GHz for a church?
Usually for range, rarely for product choice. Longer wavelengths carry further and through obstacles better, so 900 MHz typically reaches 150 to 250 feet against about 100 feet at 2.4 GHz. But far fewer systems are sold for 900 MHz, which means fewer capsules, fewer rack receivers and a thinner spares market when something breaks.
Will our cordless office phone interfere with a 900 MHz microphone?
It can, and it is the most common cause of trouble in this band. An older cordless handset transmits continuously for the length of a call and will sit on a microphone frequency without knowing it is there. If you are considering 900 MHz, audit the cordless phones in the building first, and replace the older ones with models on a different band.
Does 900 MHz need frequency coordination?
Not in the television band sense, because there are no broadcasters to avoid and no channel occupancy to look up. Modern systems here manage their own frequencies. What you do still need is an awareness of what else in the building transmits in the band, since none of it is obliged to move for a church service.
Can I mix 900 MHz and UHF systems in one church?
Yes, and it is often a sensible plan. Put the roaming preaching channel in UHF where the range and power margin are best, and put short throw fixed positions on a licence-free band. Mixing bands also means a single source of interference cannot take out every channel at once, which is a real reliability advantage.
Researched, not professional advice. This page is compiled from published manufacturer specifications, operator manuals, FCC rules, published standards and owner-review consensus, not hands-on testing. Sound system design, rigging loudspeakers overhead, and any electrical work are jobs for a qualified professional: have flown loudspeakers and their attachment points signed off by a structural engineer or a certified rigger, and have all wiring done by a licensed electrician to your local code. Wireless microphone rules change, so confirm the current FCC position before buying. As an Amazon Associate we earn from qualifying purchases.