Phones throughout Northern Ireland sounded with a siren today as part of a test for a new emergency alert system across Northern Ireland and Great Britain.
The loud alarm was planned to ring between 3pm and 4pm on all devices that were using 4G and 5G networks.
The alert rang for ten seconds and displayed a message notifying phone users that no action was needed in response to the test.
The test message that appeared on phones said: "This is a test of Emergency Alerts, a new UK Government service that will warn you if there's a life-threatening emergency nearby.
"In a real emergency, follow the instructions in the alert to keep yourself and others safe.
"Visit gov.uk/alerts for more information.
"This is a test. You do not need to take any action."
Some smartphones also read out the message to recipients.
Following the test, some users reported receiving the message a minute or so early.
However, others said their phone did not display the message or make a sound.
Phones that were powered off or switched to airplane mode were not expected to sound.
The emergency alert system is designed to warn the public if there is a danger to life nearby.
In future, a similarly loud notification and message will be sent to those the British government is seeking to reach.
Once established, the system is intended to be used in life-threatening situations including flooding and wildfires.
Earlier, Ireland's Road Safety Authority (RSA) said mobile phone users near border areas who roamed onto a UK network between 3pm and 4pm would receive the alert.
