India-Pakistan Tensions: The Government of India has announced a nationwide civil defence mock drill on May 7, 2025, amid heightened tensions with Pakistan following the April 22 Pahalgam terror attack, which claimed the lives of 26 Indian tourists in Jammu and Kashmir. During the mock drill, an air raid warning siren will be activated to simulate emergency conditions.
As part of the exercise, civilians—including school students—will take part in training sessions designed to improve their preparedness and ability to protect themselves during hostile attacks. One common question that arises is: What is an air raid siren? How does it work, and will our smartphones respond to it? In this article, we will try to answer all your questions.
What Is An Air Raid Siren?
An air raid siren is a loud, distinctive alarm used to alert the public of imminent threats such as aerial attacks or missile strikes. In some situations, these sirens are also activated during natural disasters. Typically, the siren sounds for about 60 seconds, signaling people to seek immediate shelter. Once the air raid siren stops, it generally indicates that it is safe for people to leave their shelters and resume normal activities.
Air Raid Siren: How This Technology Works
The technology is expected to be used for the India’s mock drill siren remains unclear. However, globally, air raid sirens operate using various mechanisms—ranging from air-powered systems and electric devices to advanced electronic models. Air-powered sirens create loud sound waves by channeling air through spinning discs with small holes.
In contrast, electric sirens generate sound using diaphragms or horns. More recently, electronic sirens with built-in speakers have become increasingly common, delivering digitally controlled tones with improved accuracy. Many of these modern systems can also connect to radio frequencies, enabling broader and more efficient communication.
Air Raid Siren: Will Smartphones Issue Alerts During Mock Drill?
There has been speculation that smartphones might emit alerts during the mock drill. To understand this possibility, we looked at similar systems tested in other countries. For example, the UK tested an emergency mobile alert system two years ago in 2023. During the test, all 4G and 5G smartphones received an emergency message along with a loud beep and vibration—regardless of whether the phone was on silent mode. The alert lasted for approximately 10 seconds. Adding further, if your mobile phone is switched off, you will not receive the alert message.
Air Raid Sirens: Sound Patterns And Their Purpose
Air raid sirens typically use two distinct sound patterns to convey different messages. The first is a wailing or rising-and-falling tone, which lasts for one to three minutes. This wavering pitch signals an immediate threat, such as an airstrike or missile attack, and indicates that people should take shelter without delay. The second is a steady, flat tone that does not rise or fall. This “all clear” signal usually lasts about one minute and informs the public that the danger has passed and it is safe to come out of shelters and resume normal activities.
