The child from London, told the call handler that his name was "Roman" and he thought his "mummy" was dead because “she’s closing her eyes and she’s not breathing”.
He used his mother’s mobile phone to make the call.
London's Metropolitan Police released a clip of the conversation to remind parents how important it is to teach young children their address and how to use 999 in an emergency.
Roman was able to give his exact address in Kenley, Croydon and local officers and an ambulance were dispatched immediately to the family home.
Thirteen minutes after receiving the call, officers arrived and managed to force entry into the house where they found the boy, his twin brother, younger brother and their mother, who was lying unconscious on the floor.
Paramedics were able to give life-saving first aid to the woman and she was taken to hospital after regaining consciousness at the home, police said.
It later emerged that the boy used his mother's smartphone to get in touch with paramedics, after unlocking it by pressing her thumb on the phone. He then used the Siri function to ask for help and the app dialled 999, putting him through to emergency services.
Chief Superintendent Ade Adelekan said: “Hearing this call brings home the importance of teaching your young child their home address and how to call police or emergency services in an emergency situation.
”If you do nothing else today, then I'd implore any parents of young children to sit down with them and make sure they know what to do in this kind of situation and that they know how to contact police or other emergency services in an emergency. As this case demonstrates so poignantly, it could really be the difference between life and death."
He added: “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.”
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