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Is it legal in the United Stated to operate a mobile/cellular network in the "unlicensed" 915 MHz ISM frequency band? I mean given I have all other permissions needed (mobile network service license etc.) except the frequency spectrum license.

The technology used may be GSM/UMTS/LTE. The mobile network frequencies (2G/3G/4G) partially overlap the 902-928 MHz ISM band so this should be technically possible (channels in 902-915 + 925-928 MHz) even though naturally this limits the network bandwidth while respecting the maximum ISM band radio power.

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    AFAIK you can use a radio if any rule works for your particular situation (not just the frequency). So if there is a rule that says anyone can use this frequency for anything up to a particular power level, you can do that. If there is another rule that says you can use it following amateur radio rules, you can also do that, but those rules are more restrictive, but you can also choose the less restrictive rules if you meet the requirements (low power level). Commented Mar 20, 2023 at 16:03
  • You tagged this business. Are you planning to run this as a commercial service? Or free of charge?
    – SQB
    Commented Mar 21, 2023 at 10:29
  • @SQB The business model is not relevant in the question (which is about legality). It could be run commercially or free (if someone would sponsor it).
    – Kozuch
    Commented Mar 21, 2023 at 11:15
  • Well, we're talking about licenses here. As a comment on my answer mentions, a license may be restricted to non-commercial use.
    – SQB
    Commented Mar 21, 2023 at 13:37
  • @SQB I am not a lawyer but I think ISM bands (worldwide) are not restricted to non-commercial business models, there are a lot of ISP all around using WiFi for commercial access points or for full WISP service etc. And the rules are the same for all ISM bands.
    – Kozuch
    Commented Mar 22, 2023 at 13:08

2 Answers 2

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Yes you can, subject to your equipment meeting applicable FCC Part 15 regulations. Ricochet Wireless did exactly what you proposed, running a mobile data network at 900 MHz.

Currently, carriers including Verizon run LTE in the 5 GHz Wi-Fi band.

However, there's a potentially better choice, the Citizens Broadband Radio Service. This is a "lightly" licensed service, with cheaper and free licenses that are coordinated in shared spectrum. Companies run private CBRS LTE and you can buy small base stations like Wi-Fi access points. More importantly, many commercial handsets support this frequency band, like newer iPhones.

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Well, according to a DEF CON talk by Chris Paget, "Practical Cellphone Spying" (starting a couple of seconds before the 10 minute mark), the 902MHz–928MHz ISM band is also an amateur radio band.

So it seems you could try either the ISM route or the Ham route. If you adhere to the rules for amateur radio, you could consider yourself an amateur radio operator and as such should be allowed to use the band.

  • You need an amateur radio license
  • There's a 1500W power limit
  • Specifications must be public (not a problem for GSM)
  • No cryptography allowed
  • There are RF exposure limits (but you're not likely to hit those)
  • Your station must identify itself every 10 minutes
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    I'm not clear how this addresses the question. The ISM band is "unlicensed" which means that the OPERATOR doesn't need a license but the equipment must be FCC certified and I know that ISM does NOT permit any use of 1500W output power.
    – jwh20
    Commented Mar 20, 2023 at 14:24
  • @jwh20 902–928MHz is an amateur band as well, though, as explained in that talk.
    – SQB
    Commented Mar 20, 2023 at 15:06
  • Amateur use wasn't the question. Note that the OP says "...operate a mobile/cellular network in the "unlicensed" 915 MHz ISM frequency band?"
    – jwh20
    Commented Mar 20, 2023 at 15:23
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    I disagree with your statement: "If you adhere to the rules for amateur radio, you could consider yourself an amateur radio operator and as such should be allowed to use the band." Regardless of what you adhere to, the only way, in the USA at least, to be an Amateur Radio Operator is to be licensed by the FCC as such. Operating as an amateur without the appropriate license opens you up to significant civil and criminal liability.
    – jwh20
    Commented Mar 20, 2023 at 15:40
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    One amateur radio requirement is not charging for one's services, which seems incompatible with the "business" tag on the original post. It also means that, usually, all the participants in a conversation must be licensed amateur radio operators. Commented Mar 20, 2023 at 15:51

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