Investigators into Victoria's triple-zero response times sent three letters to the emergency services minister about call-takers not keeping up with requests for ambulances during the COVID-19 pandemic.
The pressure on triple zero was close to replicating the state's 2016 thunderstorm asthma emergency - the single biggest event for Ambulance Victoria - "on a daily basis with no end in sight", one letter stated.
However, the Inspector-General for Emergency Management (IGEM) did not escalate its response for another three months.
An inquest is under way after Nick Panagiotopoulos, 47, died from a heart attack after waiting more than 16 minutes for a triple zero operator to answer in October 2021.
IGEM monitors and investigates non-financial performance of Victoria's Emergency Services Telecommunications Authority (ESTA), which is now called Triple Zero Victoria.
IGEM senior officer Christopher Mercovich said October 2021 was the busiest period for ambulance requests at ESTA.
"The performance was 47.4 per cent of calls answered at or within five seconds," he told the court.
ESTA's benchmark was to answer 90 per cent of ambulance calls within five seconds.
Response times continued to worsen and by January 2022, ESTA was only answering 39 per cent of those calls within five seconds, he said.
"The main issue was ESTA didn't have the call-takers to be able to meet this increased demand on a daily basis," Mr Mercovich said.
Mr Mercovich said ESTA was "reticent" to seek funding to increase staffing in 2020 because of a belief that it had overspent that year.
"It was not going to be a good look for ESTA to request additional funding at that time," he said.
He said three letters were sent to the state's emergency services minister about the deterioration in response times, between October and November 2021, but IGEM did not further escalate as it "is not ESTA's regulator".
Unlike Worksafe Victoria, he said IGEM did not have the power to "go in and fix things".
"That responsibility is on ESTA," Mr Mercovich said.
"It is not the role of IGEM to come over the top of ESTA … and interfere in their operations in the middle of a global pandemic."
In the letters, he said IGEM outlined the actions ESTA was taking to fix issues by employing and training additional staff to keep up with the call demand.
Council assisting the coroner, Georgina Coghlan KC, asked Mr Mercovich whether the inspector could have recommended the minister urgently inject funding due to ESTA reaching a crisis point.
"Legally, IGEM could've made a recommendation like that… but I dont think it would've been appropriate," he said.
Mr Mercovich said the third letter informed the minister of IGEM's intention to review the ESTA response, but this was not formally started until January 2022 - almost two years into the global pandemic.
IGEM deliberately waited for a separate review from former chief police commissioner Graham Ashton to be completed first.
The IGEM review found ESTA could not provide enough call-takers to meet the increased demand due to its funding model and there was a lack of information in the community about when was appropriate to call triple zero.
Queensland, which has a smaller population that Victoria, took more emergency ambulance calls in 2022, he said.
The inquest before Coroner Catherine Fitzgerald continues.
