Rapid mobile alarms are on the way

Government warnings about floods, terrorist attacks and other threats could soon be delivered directly to our phones – and not via SMS

Government warnings about floods, terrorist attacks and other threats could soon be delivered directly to our phones – and not via slow SMS.

It doesn’t require any phone numbers or any knowledge of which handsets are in a particular area

W hen the first lockdown began in March last year, phones around the country started to ping with a text message. “GOV.UK CORONAVIRUS ALERT”, the message began, with a link to new rules that we had to follow. Alas, not everyone got the text right away.

“When you send SMS messages on such a vast scale, you have to batch them up because you cause network congestion,” explained Frazer Rhodes, who had been working with the Environment Agency on flooding alerts, and became part of a team from across the government that worked to build a new, better emergency alert system for mobile phones. “So what we saw is those text messages going out and taking anything up to 72 hours to actually land on phones.”

This was far from ideal, which is why in June and July 2021, Rhodes and his team conducted the first major public trial of a new alert system in the UK. The system, which has been in use for several years around the world, is specifically designed for emergency alerts, and is capable of overriding your phone’s volume settings to blast a siren if the emergency is particularly severe.

Under the hood, it’s based on Cell Broadcast technology, which has been around since the early days of mobile phones. Instead of relying on networks to send messages, it uses the cell towers to send a message directly to phones. This also makes it easier to target warnings such as flood alerts at a particular geographic area.

“It doesn’t require any telephone numbers or any knowledge of which handsets are in a particular area,” said Rhodes, pointing to another big advantage of the system.

“The people who are most at risk [during emergencies such as floods] are people who are visitors to the area, and that could include international tourists, and therefore they are not going to be opted into a flood

warning system. But if they’re roaming on UK networks, then you have got the ability to use Cell Broadcast to reach those individuals.”

The other advantage of this approach is that alerts can be left broadcasting from the transmitter, so if someone drives into the affected area and their phone connects to the mast, the alert will pop up on their phone too.

Ten-second warning

Perhaps most crucially, though, the Cell Broadcast system is fast. “There’s no network congestion issues whatsoever,” said Rhodes, adding that alerts are received in as little as ten seconds after they have been sent.

But this doesn’t mean the government can be too trigger-happy. Before the pandemic, Rhodes worked on an early trial of the technology with the University of Hull and EE, looking at the behavioural response to alerts. “If you overuse a service like this, then of course, people start to switch off, so you do need to keep that threshold high at [the level of] saving lives,” he explained.

By all accounts, the first tests appeared to go well, but real-world usage could be staggered because of the complex way the government is structured, with different agencies and departments responsible for different types of emergency.

“We’ll onboard various hazards and threats as it goes along, as opposed to perhaps what they might have done in other countries where they’ve done a lot of planning in advance, and then launched with all hazards and threats from day one,” said Rhodes.