Why You Did Not Get an Emergency Alert on Your Phone

Direct answer: there are two completely different ways a warning reaches a phone, and they fail for different reasons. Cell broadcast alerts — the loud government ones — are pushed from the mobile towers covering an area, so you miss them if your country has no such system, if the authority did not send one, if you were not on a tower inside the targeted area, or if the alert category is switched off in your phone settings. App notifications travel over the internet instead, so they need working data and are routinely delayed or suppressed by battery optimisation. Neither is guaranteed, which is why no plan should depend on a single one.

Two different systems, often confused

Almost every argument about missed alerts comes from people comparing two things that work nothing alike.

• Cell broadcast is the technology behind official government alerts. The message is transmitted by the mobile towers themselves to every compatible handset in range, in the way a radio station broadcasts to every radio. It does not use your data connection, it does not need your phone number, nobody knows who received it, and it works when the network is too congested for calls. This is what makes it the right tool for warnings.
• App notifications — including ours — travel over the ordinary internet to a specific device. That makes them flexible: they can be about a place you are not standing in, which is precisely what someone watching family abroad needs. It also makes them dependent on data, on the phone being allowed to wake up, and on servers being reachable.

A government cell broadcast is authoritative and local. An app alert is personal and remote. They are complements, not substitutes, and neither replaces the other.

The six reasons, in the order they actually fail

1. Your country has no public warning system, or not for this hazard. This is the commonest reason worldwide and it is invisible from the handset — the phone behaves normally, because there was nothing to receive. Systems are rolled out hazard by hazard: a country may broadcast for cyclones and not for floods.
2. No alert was issued. Warnings are a decision, not an automatic consequence of an event. An authority may judge an event below threshold, may still be verifying, or may be issuing through radio and television only.
3. You were not inside the targeted area. Cell broadcast is aimed at specific cells. Coverage does not follow district boundaries neatly, so being a street outside the polygon, or being connected to a tower that is physically distant, is enough to miss it — and equally, to receive one for somewhere you are not.
4. The category is switched off on your phone. Most handsets group these into severe, extreme and public-safety categories, and some are user-switchable. People turn them off after being woken by a test and forget.
5. The phone could not receive it. Powered off, aeroplane mode, no signal, or a very old or grey-import handset whose radio does not support the local broadcast channels.
6. An app notification was delayed or dropped. Battery optimisation is the usual culprit: modern Android and iOS aggressively suspend background work, and an app that is asleep does not check anything. Add no data coverage, a full notification tray, or Do Not Disturb, and the message arrives late or silently.

Why battery optimisation is the one that catches people out

This is worth stating plainly because we hit it building our own app. Both mobile operating systems decide, on their own, how often a backgrounded app may wake up, and they get stricter the less you use it. An alerting app is by nature one you rarely open — so it is exactly the kind the system decides to throttle hardest. The result is a notification that arrives correctly on a phone in daily use and an hour late on one that sat in a drawer.

There is no honest way to promise around this. What an app can do is be truthful about when it last managed to check, which is why ours shows that on its settings screen rather than implying a watch it is not keeping. If you rely on any alerting app, exempt it from battery optimisation in your phone settings, and treat a long gap since its last check as information rather than as reassurance.

What to do about it

• Turn the government categories back on. In your phone settings, find emergency or wireless alerts and enable everything except the routine tests if the tests bother you. These are the alerts most likely to be about you, right where you are.
• Exempt any alerting app from battery optimisation, and allow it to run in the background.
• Do not rely on one channel. Radio still works when the mobile network does not, and it needs no data. See what to do when the network is down.
• Know who issues warnings where you are. Each of our country pages links that country's official meteorological and disaster agencies; their site or social feed is the primary channel, and it does not depend on your handset supporting anything.
• For fast-onset hazards, do not wait for a phone at all. Earthquake early warning gives seconds and only in a few countries — see how earthquake early warning works. For tsunami, strong or long shaking near a coast is itself the warning, and moving to high ground should not wait for a message. That is covered in tsunami warning systems.

Getting an alert for somewhere you are not

Cell broadcast can only tell you about the ground you are standing on. If the people you worry about live somewhere else — and for a great many people they do — no government system will ever notify you, because you are not in the area being warned.

That gap is the reason app-based, place-based alerting exists at all, including ours. It is also why it should be understood for what it is: a second, softer layer that watches a place on your behalf over the internet, on top of the authoritative local broadcast, and not a replacement for it.

If you did get an alert and did not understand it

Colours and words differ by country, and the same red does not mean the same thing everywhere. What disaster alert levels actually mean sets out the differences and the one distinction worth memorising: a watch is about possibility, a warning is about certainty.

This article explains how warning delivery works in general. This site is not a warning authority and does not operate any government alerting system; for warnings where you live, use your national agency.

Frequently asked questions

Why did my friend get an emergency alert and I did not?

Most often because you were connected to a different mobile cell. Government alerts are broadcast by the towers covering a targeted area, and that area does not follow district boundaries neatly — being a street outside it, or attached to a more distant tower, is enough to miss one. The other common reasons are that the alert category is switched off in your phone settings, or that your handset does not support the local broadcast channels.

Do emergency alerts need mobile data or a signal?

Government cell broadcast alerts do not use your data connection and do not need your phone number — the towers transmit them to every compatible handset in range, which is why they still work when the network is too congested for calls. You do need to be in range of a working tower. App notifications are different: they travel over the internet and need working data.

Why are app alerts sometimes delayed by an hour?

Battery optimisation. Both Android and iOS suspend background work for apps you rarely open, and an alerting app is by nature one you rarely open, so it is throttled hardest. Exempting the app from battery optimisation in your phone settings is the single most effective fix.

How do I turn emergency alerts back on?

On most phones the setting is under notifications or safety, listed as emergency alerts or wireless alerts, with separate switches for severe, extreme and test categories. Enable everything except the periodic tests if those are what made you turn them off. On Android the exact path varies by manufacturer.

Can I get an alert about a place I am not in?

Not from a government cell broadcast — it can only reach handsets in the area being warned. For a place you do not live in, such as where family lives, you need an app or service that watches that location over the internet and notifies you wherever you are.

Is any alerting system guaranteed?

No, and anyone claiming otherwise is wrong. Government broadcasts depend on a system existing for that hazard, a decision to issue, tower coverage and handset support. App alerts depend on data and on the operating system letting the app wake up. Use both, keep a radio, and for fast-onset hazards act on the physical signs rather than waiting for a message.

Sources

• ITU — Common Alerting Protocol and public warning systems
• WMO — Multi-Hazard Early Warning Systems and Early Warnings for All
• GSMA — Mobile network operators and cell broadcast for public warning
• UNDRR — Early warning systems and last-mile dissemination
• FEMA / NOAA — Wireless Emergency Alerts overview
• Android Developers — background execution limits and Doze
• Apple — Government alerts and notification settings

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