Ambulances will no longer be sent to minor 111 calls as part of sweeping changes to help stem St John's $15 million-a-year loss.
Instead, such calls will be redirected to a GP or other health care, or a St John officer will be sent in a car - not a double-crewed ambulance.
St John's annual operating loss has nearly doubled from $8 million in five years, and ambulance bosses say that is
A steadily increasing number of elderly people with chronic illnesses has paramedics struggling to cope with an annual 4.5 per cent increase in demand.
Last year, the ambulance service received a record 337,000 emergency callouts.
Response times to 111 callouts have also deteriorated - particularly in urban areas - and will continue to do so unless the service's cash shortage is addressed by the Ministry of Health and ACC, said St John's operations manager Michael Brooke.
Under the new system, ''nonurgent'' 111 calls will be coded ''grey'' or ''green''.
They will include abdominal pain, allergies, animal bites, assaults, back pain, falls, headaches, exposure to cold, lacerations, and feeling sick.
The Ministry of Health and the Accident Compensation Corporation pay 80 per cent of St John's funding, totalling $223 million in the 2010/11 financial year.
Mr Brooke said St John was working with the two Government funders, but was also changing the way its ambulance service is run.
Ambulances are now sent to geographic zones based on predicted demand, calculated from call data, rather than returning to the station when a job is finished.
''We got through winter that way. With the same number of staff, we've mopped up the 4.5 per cent growth. If we had to put more staff on, that would have cost us $2 million.''
Another change is in the way 111 calls are handled.
''A lot of people don't need to be transported to hospital,'' said Mr Brooke.
''At the moment, we send a big white truck with two people in it. That means an ambulance is tied up. This is not about turning people away, it's about sending them to the right place.''
He said 10 to 15 per cent of all emergency calls were nonurgent.
''That's a massive part of our workload. If we can reduce that, we can concentrate on getting to the life-threatening calls quicker.''
A trial of the new system will start in Christchurch next month, with a view to introducing it throughout the country.
But Mr Brooke said the changes would only ''buy us some time''.
''We think we can buy two years,'' he said.