A woman was found dead by paramedics who arrived two hours after she rang for an ambulance, an inquest heard.
Jeanette Charity, 47, of Gorleston, Norfolk, told the 999 call handler she had abdominal pains and was having breathing difficulties.
Norfolk Coroner's Court heard the handler wrongly assessed her level of need as non-urgent and failed to send an ambulance to her immediately.
The coroner concluded Mrs Charity died of natural causes despite the delay.
Depression and anxiety
The inquest heard Mrs Charity had a history of complex medical problems.
She lived with her sister, Andrea Arger, who said she was dependant on alcohol, had asthma, and took prescribed and non-prescribed drugs for pain caused by severe osteoarthritis and spondylitis of the spine.
Mrs Charity was described in court as obese, suffered from depression and anxiety and had once been sectioned by the Norfolk and Suffolk Foundation Trust.
Mrs Arger also said her sister had often dialled 999 thinking she required an ambulance.
On 26 January 2017, at 03:11 GMT, Mrs Charity dialled 999 from her mobile phone while in bed.
The ambulance arrived at 05:16 after the call handler coded her call as that for stomach pains as opposed to breathing problems.
Chris Hewitson, from the East of England Ambulance Service Trust, said had her breathing difficulties been entered into the computer system by the call handler, then an ambulance would have been despatched immediately.
Paramedics were only sent out after a consultant intervened at 05:11.
Mr Hewitson said the categorisation mistake was a case of "human error" by the call handler.
However, Norfolk coroner Johanna Thompson said: "While there was a delay in the ambulance attending, the evidence does not reveal whether the delay caused or contributed to her death."
She said the medical cause of death was left ventricular hypertrophy and obesity.