denntatsu: Offline Walkie PTT

Never lose touch with your group — even where there's no cell signal.

denntatsu is an offline walkie-talkie app. It works peer-to-peer, device to device: no server, no account, and no mobile data for your calls. Phones nearby connect straight to each other over Bluetooth and Wi-Fi, so you can talk push-to-talk (PTT) style, just like a real two-way radio. The phone in your pocket becomes the walkie-talkie.

WHO IT'S FOR
- Riders looking for a motorcycle intercom alternative that works on the phone they already carry
- Hikers and trekkers staying in touch far outside coverage
- Campers, anglers and families spread out across a site
- Airsoft and paintball teams that need squad comms
- Event crews and work sites that need radio-style comms on the spot
- Anyone who wants a backup way to reach the people nearby when the mobile network goes down

FEATURES
- No server required — connects directly with nearby devices, even without internet or cellular service
- Push to talk — hold the button to speak, release to listen. It feels like a real walkie-talkie
- No extra hardware — nothing to buy, charge or carry. Just install the app on the phones you already own
- Join by QR code — the host shows a code on screen, everyone else scans it
- No account — no sign-up, no phone number, no email address
- Text chat as well — for when you can't, or don't want to, speak out loud
- Disaster/SOS mode — safety check-ins and rescue requests are completely free and unlimited. This is not a substitute for official emergency services and does not guarantee delivery.
- P2P mesh relay — devices running the same app automatically form a mesh network, relaying safety and SOS information phone to phone, bucket-brigade style
- Works offline for safety/SOS sharing — view and post safety and SOS information over the mesh network with no internet connection

HOW IT WORKS
1. One person creates a group and shows a QR code on screen
2. Everyone else scans that code to join
3. Hold the button to talk, release to hear the others

FAQ
Q. Do I need a radio licence?
A. No. denntatsu uses Bluetooth and Wi-Fi, so no amateur radio licence or certification is required.

Q. How is this different from a motorcycle intercom or a handheld two-way radio?
A. There is no dedicated hardware to buy — it runs on the phone you already carry. Range and radio stability are different from purpose-built radio equipment, so choose whichever suits the job.

Q. Does talking use my data plan?
A. No. Voice travels directly between the devices, so calls don't use mobile data.

Q. Does it really work with no bars?
A. Yes. It doesn't rely on cell towers. Devices connect straight to each other, so it works where there is no mobile coverage.

Q. Is it free?
A. Yes — everyday calls are free. On the free plan a single connection lasts up to 30 minutes; when the time is up you can reconnect and carry straight on. Disaster/SOS mode is completely free and unlimited.

Note: Mesh relay works between Android devices. denntatsu is designed for use among nearby group members. Range and quality vary with your surroundings (obstacles, interference, etc.). Operating the app while riding or driving may violate traffic laws — please use it only when stopped.