Walkie-talkie channels and privacy codes: FRS, GMRS and PMR446

How to get two walkie-talkies on the same channel

Two radios hear each other when three settings match: the channel, the tone and the mode (analog or digital). The brand does not matter. On FRS and GMRS, channels 1-22 are the same frequencies on every radio.12

Pick both radios, the channel and the code in the matcher, and it shows the setting that puts the second radio on the same frequency and tone.

I keep both radios on code off (0 or oF, depending on the brand) while I pair them. A radio with the code off receives every call, so channel problems show up first. Add the code once both radios talk.34

FRS channels and frequencies

FRS is the US license-free service with 22 channels around 462 and 467 MHz, each 12.5 kHz wide. Channels 1-7 and 15-22 allow 2 W ERP. Channels 8-14 are limited to 0.5 W ERP.1 Radios must be certified and keep a non-removable antenna, and no license is needed.5

GMRS channels and repeater channels

GMRS uses the same 22 channel numbers and the same frequencies, so an FRS radio and a GMRS radio on channel 3 are on one frequency. GMRS allows more power: 5 W ERP on channels 1-7, with channels 8-14 still at 0.5 W for hand-helds.2 Using GMRS needs an individual license, with no exam.6 More on the two services in FRS and GMRS walkie-talkies.

The 467 MHz main channels, 467.5500-467.7250 MHz, are repeater inputs. A hand-held may use them only through a repeater or for brief tests, and the labels 15R-22R are a retail convention.2

PMR446 channels in Europe and the UK

PMR446 has 16 analog channels from 446.00625 to 446.19375 MHz, 12.5 kHz apart. Radios are hand-portable with an integral antenna, power is limited to 0.5 W ERP, and no individual license is needed.7 The decision fixes the first carrier and the spacing, so the numbers 1-16 are a convention.8 UK rules in Ofcom's interface requirement also cover hand-portable sets with built-in antennas.9

Older radios built for the pre-2016 plan have 8 analog channels in 446.000-446.100 MHz, on the same frequencies as channels 1-8 of today.108 Use 1-8 when one radio is older.

Digital PMR446 comes in two standards. They use different channel widths, so set both radios to the same mode before you compare channels.78

Privacy codes: CTCSS and DCS explained

Squelch is the gate that keeps a receiver silent until a signal arrives. A privacy code adds a second condition: the speaker opens only when the signal carries the receiver's tone or code.11

• CTCSS is a steady low tone sent under the voice. Consumer radios offer 38 tones from 67.0 to 250.3 Hz.1112
• DCS is a three-digit digital code such as 023 or 754. Most radios offer 83 of them, and some add 21 more, 104 in all.1113
• A radio set to CTCSS does not open for DCS, and the reverse. Both radios use the same system and the same number.14

A code is not encryption. Anyone on the channel with the code off hears you, and so does anyone who sets the same code.1215

CTCSS tones 1-38, the same list on Motorola, Midland, Uniden and Rocky Talkie:11

Code numbers by brand

Tones 1-38 carry the same numbers across brands. Uniden's manual says it directly: only tones 1-38 are standard across brands.4 The DCS part differs in numbering and list length.

The same 83 DCS codes, from 023 to 754, appear in the same order on Motorola, Uniden SX409 and Rocky Mountain (39-121), and on Midland (DCS 1-83). So DCS 023 is code 39 on a Motorola and DCS 1 on a Midland: the Motorola number is the Midland DCS number plus 38.11161820 The 21 extra codes on 104-code radios have no match on a 121-code radio.1317

For two radios of different brands, choose a CTCSS number from 1-38. It is the same tone everywhere.

Why two radios do not talk

• Different channel. Match the channel number and the service. On a Rocky Talkie Mountain Radio, choose 1-22: channels 23-128 carry a preset code.20
• Different tone. Match the tone, not just the number. Above 38 the numbers differ by brand.
• CTCSS on one radio, DCS on the other. Set the same system.14
• Code on one radio only. The radio with the code off hears everything, but its calls do not open a radio that has a code set.34
• Factory tone. The Retevis RT622P ships with 114.8 Hz on channels 1-8 and D026N on channels 9-16.23
• FRS against PMR446. FRS sits at 462 and 467 MHz and PMR446 at 446.0-446.2 MHz. Ofcom says US FRS sets cannot be used license-exempt in the UK, and 446 MHz is a US amateur band.2425
• Analog against digital. Match the mode on both radios.
• VOX or scan on. Switch both off while you test.
• Range. At 0.5 W, expect a few hundred meters in a town and up to a few kilometers in the countryside.26

Questions

Sources

1. 47 CFR 95.563, FRS channels · eCFR
2. 47 CFR 95.1763, GMRS channels · eCFR
3. Motorola Talkabout T600/T605 user guide · Motorola Solutions
4. Uniden SX507-2CKHS owner's manual · Uniden
5. 47 CFR Part 95 Subpart B, FRS · eCFR
6. 47 CFR 95.1705, individual licenses required · eCFR
7. ECC/DEC/(15)05, harmonised 446.0-446.2 MHz range for PMR446 · CEPT
8. ECC/DEC/(15)05 decision text, channel plans · CEPT
9. UK Interface Requirement 2030 · Ofcom
10. ERC/DEC/(98)25, withdrawn 8-channel PMR446 arrangement · CEPT