9,000 callers hang up on emergency calls in Northern Ireland
More than 9,000 emergency calls to the Ambulance Service were abandoned in the last two years.
In each case the caller hung up before an operator would answer.
Figures show how hundreds of 999 calls are not being answered within the two-second target every month.
Ambulance crews are also taking longer to deal with emergency calls.
In the 12 months to April the average response time to a category A call - where the situation is described as immediately life-threatening - was over 10 minutes.
That is two minutes above the target time.
The figures were released by Health Minister Michelle O'Neill after an Assembly question from UUP MLA Robbie Butler.
He said the response was "hugely concerning".
"The importance of ambulances and other emergency services arriving on time cannot be emphasised enough," he said.
"The longer someone has to wait for help in many of these situations, the greater the risk of them coming to serious harm."
The figures show:
- The Ambulance Service received 3,610 abandoned calls in the 12 months to April, and a further 5,424 in the previous year;
- The average response time to category A calls in the last year was 10 minutes and 17 seconds, up from nine minutes 37 seconds the previous year;
- Around 1,100 emergency calls a month on average were not answered within the target two seconds last year. The average delay was around 6.3 seconds.
Before being elected as an MLA for Lagan Valley earlier this year, Mr Butler worked as a firefighter.
He said it was crucial that all emergency calls were responded to immediately.
"Shortly before being elected to the Assembly in May I experienced what a delay in an ambulance response time looked like," he added.
"In my role in leading a crew in the Fire and Rescue Service I attended the scene of a major road traffic incident in Belfast with multiple casualties.
"Yet long after securing the scene and stabilising the casualties, my crew and the lone paramedic on the ground were left waiting for ambulances to come to their support.
"When people are experiencing serious medical difficulties or have unfortunately been involved in such major road traffic collisions, they deserve and expect to be seen as quickly as humanly possible.
"In many of these situations a delay can mean the difference between life and death.
A spokesman for the Ambulance Service said the 9,000 abandoned calls represented just 2.25% of the emergency calls received.
"The trust is unable to comment as to why the caller would disconnect as we have been unable to speak with them," he said.
"In relation to the hundreds of calls each month that were not answered within the two second target, NIAS would point out that this is an internal standard whereby we aim to connect with 95% of emergency calls within a two second time-frame.
"Telephony traffic through the control centre, in relation to incoming and outgoing calls, was a staggering 59,000 for the month of October. This includes calls in for 999 services, calls from GPs and other healthcare professionals and other calls relating to control business."
He said the ability to respond within the two second time-frame is hampered by volume - last year around 200,000 999 calls were made.
The spokesman added: "An additional barrier to achieving the standard lies in the need for our call takers to remain on line with a caller to provide clinical advice and reassurance while crews are en route to the scene. Examples of this would include advice on CPR and emergency childbirth.
"Within this current year our call takers are working exceptionally hard and are doing well to connect with 91% of calls within two seconds. For the 4% that sit outside the target, the delay experienced is approximately five seconds."
Earlier this week the Belfast Telegraph reported how the PSNI is arriving late to thousands of emergency calls, with one in 15 taking longer than half an hour to respond to.
In the past year, there were more than 1,300 cases where police did not show for 30 minutes.
They were among 4,500 emergency incidents across the province in which officers failed to attend in the first 15 minutes.
SDLP MLA Daniel McCrossan said he would raise the matter at the next Policing Board meeting.