This month, emergency alerts will be sent to phones across the UK as part of a test by the government.
The alerts will sound like a siren so that they will be loud enough for you to hear should there be an emergency with a message set to appear on your mobile's home screen, accompanied by a vibration which will sound for around 10 seconds.
You will be notified even if your phone is set to silent or do not disturb and depending on your device, your phone may also read out the alert.
