Voice, when the mesh isn't enough.

The mesh carries text. GMRS and MURS carry your voice. Chicago Offline runs a shared channel plan on both so any radio in the group can talk to any other — no app, no server, no internet.

ChiOff GMRS

ChiO ALL is the all-hands channel — if you only program one, program that one. TEAM 1–3 are for splitting off a work group without stepping on the main net. ROAD is the national travel/road-assist convention, deliberately left on CTCSS 141.3 so we stay compatible with the wider GMRS world instead of hiding behind our own tone.

ChiOff MURS

MURS is the license-free option — five VHF channels, 2 watts, no paperwork. It's the fastest way to get someone on the air the same day they show up.

Every MURS frequency appears twice in our plan, and that's on purpose. The Fam VHF n set carries DCS 023 so group traffic stays clean — numbered so the two wideband 154 MHz channels come first, not by MURS channel number. The plain MURS n set is the same frequency with no tone at all — carrier squelch — so any off-the-shelf MURS radio can monitor and join without knowing our tone. Don't add a tone to those, and don't renumber those either — they stay tied to the published FCC channel numbers.

UHF amateur DMR, on its own band

GMRS (Part 95E) is analog FM only — we don't carry digital simplex on the 462/467 MHz frequencies. Licensed hams in the group instead run UHF DMR simplex on 446.000, 446.025, 446.050, 446.075, and 446.100 — color code 1, timeslot 1, amateur service. That's the right home for digital experimentation.

What to buy, what to program

The channel plan is open data

None of the tables above are hand-maintained HTML somewhere. They come from SSRF-Lite — a simplified, machine-readable frequency-data format — and a generator that turns that data plus a per-radio profile into a codeplug you can import straight into your CPS.

• ssrf-lite — the public Chicagoland frequency library: repeaters, GMRS, MURS, amateur, NOAA, marine, airband.
• chioff-ssrf-shared — the shared community-net overlay. Everything on this page lives in chioff_community_net.yml.
• codeplugger — resolves SSRF data + a profile into channels, zones, and contacts for a specific radio.
• chioff-codeplugger-profiles-shared — the community profiles: which channels land in which zone, per radio model.
• OpenGD77_SSRFLite_Generator — same idea for OpenGD77 handhelds, straight to CSV.

A profile is small and readable — here's the GMRS zone from the shared DM-32UV profile:

zones:
  - id: "chioff_gmrs"
    name: "ChiOff GMRS"
    assignments:
      - "asg_chio_all"
      - "asg_chio_team1"
      - "asg_chio_team2"
      - "asg_chio_team3"
      - "asg_chio_road"
      - "asg_chio_repeater"

Change the plan in one place, regenerate, reflash. Every radio in the group stays in sync — and because the data is public, you can fork it and build your own plan on top of ours.

Common questions