St John Ambulance says it constantly reviews systems, after a coroner found a paging system failure contributed to a man's death in Cromwell in 2009.
Otago-Southland coroner David Crerar found a paging network was down the night Simon Berry had an asthma attack, and one of the St John Ambulance officers did not get the emergency message straight away.
Mr Crerar found it added eight minutes to the total response time of 24 minutes, which could have made a difference to the 32-year-old's survival.
The service development manager at St John Ambulance, Colin Lawrence, says the paging system was undergoing maintenance and the back-up system was not activated.
Mr Lawrence says there was an investigation, that it should not happen again, and in this case the problem was caused by human error.
