Not for the first time, Siri has helped save a person's life. On this occasion, a four-year-old UK boy used his unconscious mother's finger to unlock her phone and asked the virtual assistant to call the emergency services.

Roman, who lives in Kenley, Croydon, South London, used his mother's thumb to unlock her iPhone and asked Siri to dial 999 (the UK equivalent of 911). During the phone call, which you can hear in the audio clip below, the boy said his parent was "dead" and "closing her eyes and she's not breathing."

Thanks to the boy's actions, paramedics quickly arrived at the house where they found Roman, his twin, and their younger brother. Life-saving first aid was administered to his mother, who was then taken to the hospital.

As noted by Apple Insider, it's possible for iPhones to dial emergency services while they are locked. Users can select "emergency" to unlock the keypad from the lockscreen, but it's likely that Roman didn't know about the feature.

Roman has been praised by the authorities for his quick thinking and calmness in such a stressful situation.

"It's an amazing story and thanks to his quick thinking and by asking 'Siri' for help, this little boy saved his mum's life and it means she is still here and can be extremely proud of him and his brothers," said Chief Superintendent Ade Adelekan of the Met's Command and Control Unit, which handles emergency calls.

In June last year, an Australian mother thanked Apple after she used Siri to call an ambulance while performing vital CPR on her one-year-old daughter.