Offline guide

Staying in touch when the power is out

The internet in your house dies the moment the lights do. The mobile network takes longer, but not as long as most people assume.

A blackout takes your home internet with it instantly. The router is just a box that needs mains power, and so is the cabinet down the street. That part surprises nobody.

The mobile network is the part people misjudge. Cell sites have battery backup, and the big ones have generators, but backup is sized in hours rather than days. As a long outage runs on, sites drop one by one and coverage gets patchier where you are, even though your phone is fine and the company is still very much in business.

What fails, and roughly when

Home broadband and Wi-Fi go immediately. Anything in the house that depends on them — smart speakers, video doorbells, VoIP handsets — goes with them.

Mobile data usually degrades before it disappears. Sites that are still up get busy as everyone in the area falls back to them, so calls fail before texts do and data crawls before it stops.

Your own phone becomes the constraint eventually. A phone hunting for a signal it can't find burns battery fast, which is why switching off the cellular radio during a long outage buys you real hours.

What a mesh does about it

Knit doesn't need any of the infrastructure that just failed. Phones talk to each other over Bluetooth and Wi-Fi, so a street where several neighbours have the app keeps a working group chat while the grid is down. No internet or cell service is required, and nothing in the path needs mains power except the phones themselves.

Messages that can't be delivered right now wait instead of failing. If a neighbour's phone is off or out of range, what you sent moves when a path appears rather than vanishing.

Group chats are end-to-end encrypted, so a neighbourhood thread stays between the people in it even as it relays through other phones. If you want a message to reach anyone in range at all, including people you've never met, the Nearby room does that. It is an open broadcast, plaintext by design: the right tool for asking a whole street whether anyone has water, and the wrong one for anything you would not say out loud on the pavement.

Worth doing before the next one

Install it while you still have a connection. An app store you can't reach is no use to you during the outage.
Get one or two neighbours on it. One neighbour gives you someone to talk to; several give everyone else a route.
Allow it to run in the background, so your phone keeps relaying for people even while you're not looking at it.
Keep a power bank charged. Every phone that stays alive is another hop for everyone else.
Agree on a group chat name in advance, so nobody is trying to organise one at 2am in the dark.

What it is not

It is not a way to call for help. Emergency calls go through on any network, from any phone, even with no SIM and no account — that is always the first thing to try.
It only reaches as far as the people running it. On a street where nobody else has installed it, there is no mesh to join.
It doesn't restore anything. Your home internet is still down; this is a way to talk to the people around you, not to get back online.
It runs on battery like everything else. In a multi-day outage, power is the real constraint, not the app.

Common questions

Will my phone still work in a blackout?

The phone itself is fine until the battery runs out. What degrades is the network around it: home broadband goes immediately, and mobile coverage thins as cell sites work through their backup power and the remaining ones get congested.

How long do cell towers keep working without power?

It varies a lot by site and country. Backup is generally measured in hours, with larger sites carrying generators that run much longer if they can be refuelled. The practical version is that coverage in a given area gets worse the longer an outage lasts, rather than switching off all at once.

Can I use this to call the emergency services?

No, and please don't plan on it. Emergency calls are handled by the mobile network and go through on any available carrier, with no SIM and no credit. Knit is for talking to the people around you when the ordinary ways of doing that are gone.

Does it work if the mobile network is up but overloaded?

Yes, and that's a common case. Congestion is what usually stops messages during a big event, and the mesh doesn't touch the congested network at all, so it isn't affected by how many other people are trying to use it.