The class is determined jointly by the transmitter's modulation scheme, occupied bandwidth, operating band and output power; product name, form factor and intended use play no part. FCC Part 15 class codes are essentially an index of "which technical rule applies": Class C (unintentional radiators) looks at Section 15.109, while Class E (intentional radiators) is further subdivided into 15.247, 15.249, 15.407 and so on. Whichever rule applies, that is the class.
In practice, the most common mistake is treating "wireless functionality" as a single whole. A terminal with 2.4 GHz Bluetooth, 5 GHz Wi-Fi and 13.56 MHz NFC has three transmit paths corresponding to DTS (or DSS), NII and DXX respectively, each requiring separate testing and separate listing on the certificate. Conversely, the same chip operating in different modes under different firmware configurations will also lead to different classes.
According to statistics from the company's laboratory certificate database (range 05/06/2026 to 2026-10-22), DTS and DSS together account for the overwhelming majority, with NII and DXX forming the second tier.
| Equipment class code | Class name | Certificates | Share characteristics |
|---|---|---|---|
| DTS | Digital Transmission System | 2441 | Highest share; covers Wi-Fi, BLE, Zigbee and other mainstream digital modulation |
| DSS | Part 15 Spread Spectrum Transmitter | 1337 | Spread-spectrum category; Bluetooth Classic, some 2.4 GHz proprietary protocols |
| DXX | Part 15 Low Power Communication Device Transmitter | 693 | Low-power general transmitters; remote controls, sensors, NFC, etc. |
| NII | Unlicensed National Information Infrastructure TX | 344 | 5 GHz and above broadband access; Wi-Fi 5/6/6E |
| DCD | Part 15 Low Power Transmitter Below 1705 kHz | 259 | Low-frequency, low-power |
| DSC | Part 15 Security/Remote Control Transmitter | 223 | Security and remote control |
| PCB | PCS Licensed Transmitter | 137 | Licensed PCS transmitter |
| JAB | Part 15 Class B Digital Device | 74 | Unintentional radiator; few standalone applications |
| TNB | Licensed Non-Broadcast Station Transmitter | 44 | Licensed non-broadcast station |
| 8CC | Part 18 Consumer Device | 25 | Industrial, scientific and medical consumer equipment |
| UWB | Ultra Wideband Transmitter | 24 | Ultra-wideband |
| PCE | PCS Licensed Transmitter held to ear | 22 | Handheld PCS |
The database covers 26,784 companies (16,687 in China), 40,781 products, 5,953 FCC certificates and 346 testing laboratories; in the past 30 days, 1,009 new certificates were issued and 617 new companies were added. These figures show that Chinese applicants are already the majority, and the cost of a class selection error shows up directly in the rework cycle.
DTS applies to wideband systems using digital modulation, while DSS applies to direct-sequence spread spectrum and frequency-hopping spread spectrum systems; the test rules and limits differ. DTS relies on the digital modulation system provisions of 15.247, focusing on 6 dB bandwidth, power spectral density and out-of-band suppression; DSS also falls under 15.247, but assesses spread-spectrum processing gain, number of hopping channels and dwell time.
Three points decide the call: whether the modulation is a spread-spectrum scheme, whether there is processing gain, and whether channel occupancy follows a hopping sequence. Bluetooth Classic (BR/EDR) goes to DSS, while Bluetooth Low Energy (BLE) usually goes to DTS; Wi-Fi in the 2.4 GHz band is mostly applied for as DTS, with some early spread-spectrum designs applied for as DSS. When both modes coexist in one product, reports are required for both paths.
DXX covers low-power communication device transmitters not falling into other classes, while NII covers equipment in the unlicensed National Information Infrastructure bands at 5 GHz and above. DXX is common for 315/433 MHz remote controls, wireless sensors, NFC and RFID, relying on rules such as 15.249, with tighter limits and lower power; NII relies on 15.407, covering the U-NII-1 through U-NII-8 sub-bands, with the most detailed requirements for DFS radar avoidance, transmit power spectral density and out-of-band emissions.
Note that with Wi-Fi 6E and Wi-Fi 7 introducing the 6 GHz band, the 6 GHz portion is applied for under the new sub-bands of 15.407 and still belongs to the NII system, but involves more test items than traditional 5 GHz. Simply reusing an old report template will almost certainly trigger a rework request.
Choosing the wrong class leads to incorrect citation of test standards and reports that are not accepted; even an issued certificate risks revocation. This shows up in three ways: first, a request for additional testing during TCBO review, stretching the normal 3-4 weeks to more than 6 weeks; second, a mismatch between the equipment class on the certificate and the actual transmission method, making it impossible to demonstrate compliance during customs or market-supervision spot checks; third, where substantive issues such as DFS or power exceedance are involved, a hardware modification rather than a paperwork supplement may be required.
Follow three steps — band first, modulation second, power third — and most products converge on a single class within ten minutes. Step one: list all transmit paths and their bands. Step two: confirm whether each path is a spread-spectrum scheme, digital modulation or narrowband low power. Step three: check the power and bandwidth thresholds of 15.247, 15.249 and 15.407 to see whether a stricter rule is triggered. For multimode products, determine each path separately and merge them into one application.
It depends on the modulation. If it uses digital modulation with relatively wide bandwidth, apply for DTS; if it is a low-power narrowband transmitter covered by 15.249, apply for DXX. The limits and test items differ between the two, so the decision cannot be based on what the product is used for.
Usually two: the 2.4 GHz portion under DTS and the 5 GHz portion under NII. If the 5 GHz portion supports multiple sub-bands, they are still combined under one NII application, but testing must cover all operating sub-bands.
Not necessarily. Bluetooth Classic's frequency-hopping scheme goes to DSS, while Bluetooth Low Energy's digital modulation usually goes to DTS. Dual-mode chips must be assessed along both paths separately.
It cannot be changed directly. The product must be retested under the correct class and submitted as a Class II Permissive Change or a new application; the original certificate remains in a risky state until corrected.
You need to determine the equipment class and technical rule, complete the corresponding test reports, designate an authorized agent within the United States, and submit through the TCBO system. Class determination should be completed before testing begins, to avoid invalidating reports.
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