A 93-year-old woman died in a care home after staff "missed opportunities" to seek help, an inquest heard.
During her visit to Hurst Hall, Ashton-under-Lyne, Elsie Clarke's son said she was "pale" and "breathing rapidly", Stockport Coroner's Court heard.
He said staff said they would call for a GP but they mistakenly thought they had to wait for an out-of-hours medic as she was not registered locally.
Mrs Clarke could have been registered and seen immediately, the court heard.
Returning a narrative verdict, coroner John Pollard said "opportunities had been missed" and parts of Mrs Clarke's care were "sub-optimal".
Among his recommendations were improved training of staff with 999 calls, and better record keeping at the Greater Manchester care home.
He also said: "She was desperately ill. She sat there and died and nobody called an ambulance for her."
Her son, Peter Clarke, described his mother as quite a "feisty character" who had many friends and was a big Manchester City fan.
In a statement read out by the coroner, Mr Clarke described his mother as "looking as if she was dead" during the 14:00 BST visit on 10 February.
Speaking in court, he added it was "an appalling change" from earlier visits.
Mr Clarke said he spoke to staff member Katherine Murphy, who told him she would call a doctor.
He told the hearing he returned to the care home at 17:30 and said a doctor had still not been called, despite his mother's condition having deteriorated further.
He said he had been told by Ms Murphy that she would call one after she had given Mrs Clarke her medication.
The court heard Mr Clarke was at home at about 19:20 when he received a phone call from Ms Murphy, who was "quite hysterical, very alarmed, very concerned".
He said: "She explained that my mother had stopped breathing."
After returning to Hurst Hall, Mr Clarke and his wife were told she had died and there were paramedics with her.
The inquest also heard from Claire Dodd, a senior care assistant who did a health check on the morning Mrs Clarke died.
She said Mrs Clarke seemed "a little bit chesty" but otherwise all right.
Ms Dodd said she had rung a local GP, but they said she was not registered there. Because of this, she would have to wait for an out-of-hours GP to come at 18:00.
Coroner John Pollard asked Ms Dodd and Ms Murphy whether they had heard of the NHS temporary registration form, which would have allowed her to be seen that afternoon.
After both replied they had, the coroner asked why they had not used it.
Ms Murphy said she "didn't know".
Ms Dodd said she thought Mrs Clarke was already registered as she was due for blood tests later that week.
In a statement, the care home offered their "sincere apologies" to the family.
It said staff had taken on board what the corner's comments and had "already implemented" recommended measures, including improved record keeping.