iwisur Made in France

Digital independence

When the network goes down,
what is left of your phone?

A phone without a network is not a dead phone: GPS, Bluetooth, storage and the flashlight still work. But only if you installed and downloaded what you need beforehand. Here is what, in which order, and what each tool cannot do.

Preparedness guide, facts as of 3 November 2026. No commercial tie or affiliation with the tools mentioned. Items marked “In France” are specific to France.

Starting point

What stops, what keeps working

Stops with the network

  • Mobile internet: online maps, usual messaging apps, online AI assistants.
  • Calls, which saturate quickly. The French official guide asks people not to phone needlessly, to leave lines free for rescue services, and to favour messages.
  • In France, FR-Alert: the alert travels through mobile towers. It does not reach a switched-off phone or one in airplane mode.

Keeps working without a network

  • GPS: positioning comes from satellites, with no plan or internet needed. Galileo is present in more than 95% of smartphones (EUSPA).
  • Bluetooth, storage, the flashlight, and everything you downloaded beforehand.
  • In France, 112 as long as a tower answers: with a SIM card inserted, even without a plan, emergency calls work.
  • On iPhone 14 and later, Emergency SOS via satellite, outdoors with a clear view of the sky, outside any coverage.
How long does the network last? No official figure per tower is published in France. A figure of about 20 minutes, attributed to Orange in 2022, appears in a written question to the National Assembly; the press mentions 30 minutes to 2 hours. During storm Ciarán (2023), the regulator Arcep reports that one mobile operator found that 90% of the sites that went down did so for lack of electricity. No source confirms the network holding beyond 2 hours: prepare for it to be gone for much longer.

The apps

Five functions to keep, one tool for each

The principle is the same everywhere: install, download over Wi-Fi, then test in airplane mode. The sizes below are the sizes of the files themselves.

01 · KNOW

Kiwix

A library you read without a network: Wikipedia and other collections, downloaded once and for all.

Download beforehand

  • WikiMed (medicine), French: 0.86 GB; English versions exist too
  • Best of Wikipedia, no pictures: 1.5 GB (French)
  • iFixit (repair), French: 3.65 GB
  • Cooking, French: 0.26 GB
  • Full French Wikipedia, no pictures: 12.9 GB (55.4 GB with pictures)

Sizes from the official catalogue, November 2026. Pick your own language in the catalogue.

What it does not do

  • There is no dedicated French file for first aid, survival or electrical work. WikiHow is not in the catalogue.
  • The disaster-preparedness collections are in English (ready.gov: 2.06 GB).
  • Add your national guide as a PDF, and print it. In France: “Tous responsables” (about 14 MB, French).

Good to know

  • iPhone (iOS 17.6 or later) and Android (7.1 to 15). Free, open source.
  • On Android, the Google Play version only reads its own folders: uninstalling the app may erase downloaded files. The full version installs from download.kiwix.org.
  • Site: kiwix.org
02 · NAVIGATE

CoMaps or Organic Maps

OpenStreetMap maps stored on the phone, with walking, cycling and driving routes, without a network.

Download beforehand

  • Your region and the neighbouring ones. In France, one département is generally 30 to 110 MB.
  • France as a whole: about 5.4 GB with CoMaps, 4.8 GB with Organic Maps.
  • Test in airplane mode: the map displays and the blue dot moves.

Which one

Both read the same data. CoMaps is a community fork, on the stores since July 2025; it has no legal entity or elected committee yet. Organic Maps belongs to a for-profit company; contributors addressed an open letter to its shareholders challenging its governance, in March 2025. We recommend CoMaps; Organic Maps remains an acceptable choice.

What it does not do

  • No traffic and no closed roads: an offline map does not know what happened yesterday.
  • Free OsmAnd is limited to 7 map downloads on Android (5 on iPhone), and Maps+ costs 69.99 €: keep it for advanced users.
03 · TALK

BitChat, and Briar on Android

Phone-to-phone messages over Bluetooth, with no tower and no internet.

What the two apps do

  • BitChat (iPhone and Android): Bluetooth messages relayed by nearby phones, up to 7 hops. No account.
  • Briar (Android only): contact-to-contact messages over Bluetooth, local Wi-Fi or Tor. Audited by Cure53 in 2017; in maintenance mode since 9 July 2026.

The deciding point

Your relatives must have installed the same app, and tested it with you, before the crisis. Otherwise no message gets through: a proximity messenger is only worth the people who already have it.

Test it two rooms apart, then across a building or a street.

Honest limits

  • BitChat: the audit mentioned in the release notes has not been published; the authors acknowledge that metadata (device identifier, nickname) is the weak point. It is unknown whether relaying works on iPhone when the app is in the background.
  • Meshtastic reaches several kilometres, but everyone needs a LoRa radio, and the default channel key is public.
  • Avoid Bridgefy: researchers broke its security in 2021 and 2022.

In France, put this in your contacts tonight: 0 800 112 112, the number rescue services use to call you back, saved as “Services d’urgence” (rescue services use it to call you back: it is not a cold call). 114 can also be reached by text message by anyone who cannot speak.

04 · UNDERSTAND

An AI that runs on the phone

Google AI Edge Gallery or PocketPal: a small language model runs without a network, to summarise, translate, rephrase a text or describe a photo.

Install beforehand

  • Edge Gallery: Android 12 or later, iOS 17 or later, free, in beta. Gemma 4 E2B: 2.59 GB, it needs 8 GB of RAM; E4B: 3.66 GB, 12 GB of RAM (figures from the Android list; the iPhone model list is not verified).
  • PocketPal: iPhone and Android, free. Small phone: Gemma 3 1B (0.81 GB); mid-range: SmolLM3 3B (about 1.9 GB); high-end: Gemma 3 4B (about 2.5 GB).
  • Some Gemma models require a Hugging Face account: create it before the outage.

What to expect

  • On a mid-range Android phone, about 7 to 10 tokens (word fragments) per second: an answer takes half a minute or more.
  • Publishers give no figure for quality in French, and no battery-drain measurement is published. Test beforehand, charger within reach.

Warning

A local model can be confidently wrong. PocketPal’s terms do not guarantee the accuracy of answers and exclude medical advice; the Gemma 4 model card admits statements that may be incorrect or outdated. No publisher releases an evaluation of diagnosis from a photo. For a danger (electricity, gas, health), do not rely on a local AI: call your emergency number if the network answers (112 in the EU; in France also 15 and 18). For an electrical installation, switch off at the main breaker if you know how, touch nothing else, and call an electrician. For health, the French guide mainly recommends first-aid training.

05 · HOLD ON

Power: the real bottleneck

The four tools above are useless with a flat battery. A few figures so you do not buy the wrong thing.

Read watt-hours, not mAh

A power bank only gives back about 60% of its energy to the phone. Test-Achats charged a Galaxy S24 Ultra (5,000 mAh) 1.22 times with a 10,000 mAh power bank.

recharges ≈ power bank Wh × 0.6 ÷ phone Wh

Power bankiPhone 17
≈ 14 Wh		5,000 mAh phone
≈ 19 Wh
10,000 mAh (37 Wh)1.6 to 1.71.1 to 1.25
20,000 mAh (74 Wh)3.1 to 3.42.3 to 2.5

Calculated from the Test-Achats measurement. At one recharge a day, 20,000 mAh covers about 3 days for an iPhone 17, 2 to 2.5 days for a 5,000 mAh phone. For 72 hours with a large phone, aim for about 26,000 mAh or lighter use.

What to buy

  • A power bank without a panel, with USB-C in and out, capacity shown in Wh, bought from a traceable seller.
  • A separate foldable panel of about 20 W, pointed due south and tilted to 60° in winter (1.5 Wh per watt per day in December in Paris, against 0.6 Wh lying flat). Charge the power bank rather than the phone directly.
  • Two cables suited to your devices (USB-C, and Lightning for older iPhones).

A solar panel: a help, not a source

Energy produced per day by a 20 W foldable solar panel in Paris Median of 18 Wh per day in December against 80 Wh per day in June. Fully recharging an iPhone 17 through a power bank takes about 26 Wh: the December median stays below that threshold. 04080 Wh per day (median, 20 W at 60°, Paris) 18 80 December June 1 recharge ≈ 26 Wh
Calculated from PVGIS (European Commission), 2014-2023. Ceiling: clean panel, due south, no shade. In Paris in December, 58% of days stay below one recharge, with up to 8 days in a row. In June, the median is more than 4 times higher.

Why not a power bank with a built-in panel

The panel on such a unit delivers about 1.2 W. Lying flat in Paris in December, it yields about 0.7 Wh a day: nearly 30 days to recharge an iPhone 17 once. In the sun the battery heats up, while Apple advises staying below 35 °C. Que Choisir finds such panels often too small, and Test-Achats notes they charge very slowly.

Make what you have last

  • Recharge the power bank every 3 months, for instance at each change of season: a Li-ion cell loses about 17 to 20% in 3 months at rest (estimate from Battery University).
  • Low power mode, lowest brightness, background refresh off. On iPhone, the mode switches itself off at 80% charge: turn it back on after each recharge.
  • Network present: stay connected to receive alerts and text messages. Network gone: switch to airplane mode, because the phone drains itself searching for a signal (Apple), and turn it back on at fixed times to collect messages.
  • Dark mode saves only 3 to 9% at medium brightness (Purdue, 2021): lowering brightness does more.

How much room

Storage budget

ContentLightComfortable
Kiwix: WikiMed (0.86 GB) and best of Wikipedia (1.5 GB)2.36 GB2.36 GB
Kiwix: iFixit (3.65 GB) and cooking (0.26 GB)no3.91 GB
Maps: one département (up to 0.11 GB) or three (up to 0.33 GB)0.11 GB0.33 GB
Local AI: Gemma 3 1B (0.81 GB) or Gemma 4 E2B (2.59 GB)0.81 GB2.59 GB
Total, plus the official guide (14 MB)≈ 3.3 GB≈ 9.2 GB

Sum of the files listed above. Check your free space beforehand, and keep some for photos and updates.

What the phone does not replace

Beyond the phone: paper and radio

A battery-powered radio

When the mobile network is down, FM radio remains the channel for official instructions. In France, the guide asks people to tune in to radio stations, and the government site names the local public-service radio, the “ici” network (formerly France Bleu). Write down the frequency of your local station on paper: you will not be able to look it up online. The French official list does not include a hand-crank radio; only the flashlight may be dynamo-powered.

Paper, cash, light

  • Photocopies of ID and prescriptions, spare keys, kept in a waterproof pouch (“Tous responsables” guide, pp. 6-9).
  • Useful numbers, by hand: the guide includes an “Important notes” page.
  • Cash, because cash machines may stop working.
  • A flashlight and spare batteries.

Outside France, follow your own authorities: Be Ready (United Kingdom), Ready.gov (United States).

Taking action

Checklist: one evening, once and for all

  1. In France, save 0 800 112 112 under the name “Services d’urgence”.
  2. Install Kiwix and download WikiMed and the best of Wikipedia, over Wi-Fi.
  3. Install CoMaps or Organic Maps and download your département (the local map area) and its neighbours.
  4. Install BitChat with your relatives and exchange a message two rooms apart.
  5. Install a local AI if your phone has the RAM needed (about 2 GB free for Gemma 3 1B, 8 GB for Gemma 4 E2B); create the Hugging Face account if the model requires it.
  6. Save your national guide as a PDF and photos of your papers in a folder you can open offline.
  7. Write down on paper your local radio frequency and the important numbers.
  8. Charge the power bank prepare the cables, and set a reminder every 3 months.
  9. Spend 30 minutes in airplane mode and check that maps, library and messaging work.

Quick answers

The short answers

Does GPS work without a mobile network?

Yes. Positioning comes from satellites and needs no plan or internet. What is missing without a network is the maps: download them beforehand with an app such as CoMaps or Organic Maps. Galileo, the European system, is present in more than 95% of smartphones (EUSPA).

How long does the mobile network last in a power cut?

In France, no official figure per tower is published. A figure of about 20 minutes, attributed to Orange in 2022, appears in a written question to the National Assembly; the press mentions 30 minutes to 2 hours. During storm Ciarán (2023), Arcep reports that one mobile operator found that 90% of the sites that went down did so for lack of electricity. No source confirms the network holding beyond 2 hours: better to prepare for it being gone for much longer.

Can you call 112 without a phone plan?

In France, if a SIM card is present in the phone, even without a plan, emergency calls work, according to service-public.gouv.fr (page checked on 25 August 2026). A tower must still answer. Rescue services may call you back from 0 800 112 112: save that number as “Services d’urgence”.

Which power bank do you need to last 72 hours?

Think in watt-hours rather than mAh: a power bank gives back about 60% of its energy to the phone. With 20,000 mAh (about 74 Wh), count 3 recharges of an iPhone 17 and 2 to 2.5 recharges of a 5,000 mAh phone. For 72 hours with a large phone, aim for about 26,000 mAh or lighter use.

Can an offline AI replace a doctor or an electrician?

No. A local model can be confidently wrong, and PocketPal’s terms exclude medical advice. It is for summarising, translating or rephrasing a text. For a danger (electricity, gas, health), call your emergency number if the network answers (112 in the EU; in France also 15 and 18); for an electrical installation, switch off at the main breaker if you know how and call an electrician.

Checkable

Sources

Every figure comes from a source consulted on 3 November 2026. The calculations (efficiency, recharges, solar energy, storage budget) are ours, based on those sources. Apps change fast: check the version and platform before installing.

This guide is a preparedness tool. It does not replace the instructions of the authorities, FR-Alert, or the emergency services. To count your water, food and medicine reserves day by day: iwisur.