GMRS privacy codes (CTCSS/DCS) Why they aren't private and how repeater tones work

Sources: 47 CFR Part 95 via the eCFR API (version dated 2026-10-01); the Rocky Talkie user manual filed with FCC ID 2ATSN-RT5WV1 (via fccid.io); and maker pages for the radios we track, all checked 2026-10-21. Not legal advice.

What a privacy code actually is

“Privacy code,” “sub-channel,” “squelch code” and “tone” are all maker names for two standard systems:

• CTCSS (Continuous Tone-Coded Squelch System): a low tone sent under your voice, for example 67.0 Hz or 131.8 Hz.
• DCS (Digital-Coded Squelch): a repeating digital pattern sent the same way, labelled with an octal code such as 023 or 754.

The rules call these “subaudible tones used for receiver squelch activation and selective calling” and allow them “to access repeater stations” (§95.1777). Tones at 300 Hz or below may be sent continuously during a conversation (§95.377).

What it does: your radio stays silent unless the incoming signal carries your code. Rocky Talkie’s manual puts it this way: privacy codes “are used to filter incoming transmissions.”

What it doesn’t do: hide you. Anyone on that channel with the code off hears every word, and your transmission still blocks the channel for everyone else on it. The GMRS rules bar “coded messages or messages with hidden meanings” (§95.1733(a)(3)) and allow only analog voice plus simple data emissions (§95.1771). In other words, there’s no legal encrypted GMRS voice.

Why “code 20” isn’t the same on every radio

FRS and GMRS channel numbers 1–22 match across brands because the FCC numbers the FRS channels (§95.563). Privacy code numbers don’t. Each maker numbers its own list, and the lists differ in length:

The fix: look up the tone frequency or DCS code behind the number in each radio’s manual, and set that. Programming software such as CHIRP sets tones by frequency (Hz) or DCS code rather than by a maker’s code number, which avoids the guesswork on radios it supports, such as the GMRS-V2. An r/gmrs thread from October 2026, Is this even possible?, shows a GMRS HT and a Motorola FRS radio failing for exactly this reason.

Repeater tones: input and output

A repeater listens on a 467 MHz main channel and transmits on the paired 462 MHz channel, 5 MHz lower. Most repeaters only respond to a specific tone. Rocky Talkie’s manual says: “Most repeaters will require you to use a privacy code to gain access.”

• Input (transmit) tone: the tone your radio sends so the repeater opens. Without it, you’ll hear the repeater, but it won’t hear you.
• Output (receive) tone: the tone the repeater sends. Setting it on your radio keeps other traffic out of your speaker. It’s optional on most radios.
• “Split tone”: different input and output tones. Rocky Talkie notes these repeaters “are common in Colorado and a few other places,” and Midland lists split-tone repeater channels on the MXT575 and GXT67 PRO.
• Where to get them: from the repeater owner or a listing such as myGMRS. Many owners share tones only after you give them your call sign, and owners may restrict use (§95.1705(d)).

Checklist: two radios won’t talk

1. Same channel number on both? Channels 1–22 are the same frequencies on every FRS and GMRS radio.
2. Turn privacy codes off on both and test. If that works, set the same tone frequency (not just the same code number) on each.
3. Is the GMRS radio on a repeater channel (often shown as “R,” “REP” or 15R–22R)? Those transmit on 467 MHz and only work through a repeater. Use the plain channel for radio-to-radio (simplex).
4. Channels 8–14 are limited to 0.5 W ERP on HTs (chart), so range there is short. Try 15–22.
5. Is one radio a ham-mode radio locked out of GMRS transmit? See is my Baofeng legal on GMRS?
6. Still nothing? Check the manual for a tone-scan function. Some radios can detect the tone another radio is sending.

When you should use a code

• Busy channels (events, campgrounds, cities): a code keeps strangers’ chatter out of your speaker. Before you transmit, listen with the code off. The FCC asks for “listen-before-talk” so you don’t talk over others (FCC GMRS page).
• Repeaters: the input tone is usually required.
• Emergencies: consider leaving codes off on a monitoring radio, so you can hear anyone calling for help on that channel.

Related: GMRS repeaters and mobile setup · GMRS vs FRS, MURS, CB and ham · methodology glossary · program tones with CHIRP