Vic safe under triple zero trial: Napthine

Premier Denis Napthine says a new staffing system being trialled at Victoria's triple zero call centres will be stopped immediately if it compromises call-taking capacity.

Sick or absent emergency call-takers are not being replaced at emergency dispatch centres under a trial being run by the state's Emergency Services Telecommunications Authority (ESTA).

Dr Napthine said the trial had been operating since mid-July with no reductions in service.

He said any changes that compromised the call centres would be stopped.

"If there are any changes to compromise call-taking capacity they will be short-circuited, finished, stopped immediately," Dr Napthine told reporters on Tuesday.

ESTA has not been replacing up to two absent police calltakers on weeknights and weekends, two fire calltakers on night shifts and one fire call-taking position on day shifts since the trial started.

Unions say the move could leave the state vulnerable in times of emergency and disaster.

United Firefighters Union secretary Peter Marshall said any delay in emergency response could mean "life or death".

"(Dr Napthine's) methodology of using a crystal ball being able to predict when an emergency will occur is not only fatally flawed but extremely dangerous," Mr Marshall told AAP.

Police Association secretary Ron Iddles said he didn't see how the call centres' capacity can be maintained with fewer staff.

"I don't see why you would cut back staff and trial it and wait for a disaster to happen," Senior Sergeant Iddles said.

ESTA says it is trialling the ability to make real-time decisions about absences in consultation with staff.

"It makes sense not to drive up the human or other costs of overtime that we know are not needed," an ESTA spokeswoman said.

Dr Napthine said the same basic staffing levels were being maintained.

"It's always important to look at ways to deliver more efficient services," Dr Napthine said.

"We will not put community safety at risk."