St John Ambulance is unnecessarily taking up to 80,000 people to hospital each year.
St John says it is working on ways to cut the number of people taken to the emergency department to cope with a record number of people calling 111 for an ambulance.
Around 400,000 calls are made to the service each year and the number is expected to reach500,000 within five years.
Some 75% of calls attended by an ambulance end up taking someone to hospital and St John wants to cut that to 55%.
In an attempt to cut that number, chief executive Peter Bradley said St John and Wellington Free Ambulance began a trial in October called secondary triage, where non-urgent callers are given advice over the phone by a paramedic.
Hamilton and Christchurch are also trialling single response systems.
Wellington Free Ambulance began a similar service nearly three years ago in the Kapiti region, called urgent community care.
Acting chief executive Andrew Long said 65% of the first 1000 people referred to it were able to be treated from home and one ambulance per day has been freed up since the helpline service was set up.
Greypower president Roy Reid said many people use ambulances because it's cheaper and easier than after-hours care.
St John said the trials will continue for another two to three months, before being evaluated by the services and the Ministry of Health.
Decisions on how the process might work in a national level are expected to be made around July.