The author of a damning report into Victoria's triple-zero crisis says call demand was accurately forecast for COVID-19 waves, despite the premier claiming it was unforeseeable.
A report by Inspector-General for Emergency Management Tony Pearce linked 33 deaths to ambulance call delays and other related issues, although made no findings on whether faster intervention would have prevented them.
It found the Victorian government was aware of the Emergency Service Telecommunications Authority's (ESTA) precarious financial position as early as 2015 and hadn't settled on a sustainable funding model despite 10 years of work.
Premier Daniel Andrews offered a public apology to the families of those who died but argued the extent the system was overwhelmed was "not foreseeable".
"Nothing in that model would avoid the system being overwhelmed by the thousands of additional calls for day after day after day," he said on Tuesday
But Mr Pearce said ESTA forecast ahead and had predicted demand for the Delta and Omicron COVID-19 waves.
"The numbers they arrived at were very, very close," he told ABC Radio Melbourne on Wednesday.
"The problem they had was that their funding base was one that allows them to resource on a year-to-year basis for their business as usual. But what it doesn't do is provide them with enough capacity to ramp up when they get a large surge event."
ESTA's benchmark is for 90 per cent of ambulance calls to be answered within five seconds but figures blew out after Victoria moved away from lockdowns last year.
It was taking an average of 90 seconds for ESTA to answer ambulance calls in October compared to the national average of 13 seconds.
When COVID-19 cases skyrocketed across the nation in January, the national average rose to 15 seconds but Victoria's average call answer time spiked to 118 seconds.
NSW's ambulance service recruited call-takers aggressively in mid-2020 but ESTA's ad hoc supplementary funding limited its ability to hire and train enough staff to meet demand, the report found.
Mr Pearce said the authority lacked the confidence at the time to "spend money and deal with consequences" later.
"Ambulance Victoria anticipated it was going to have some significant problems. It simply went out and made sure the resources it had were as close as possible ... to meet the impact of what was coming," he said.
The Victorian government in May committed $333 million to recruit and train almost 400 extra call-takers.
"At every single point when ESTA has sought additional funding, the answer has been yes," Mr Andrews said.