Police are responding faster to emergency events, despite answering the phone slightly slower.

Four out of five calls are picked up by police within 10 seconds which has slipped slightly on last year.

But their average response time has become faster in each of the last two years around seven-and-a-half minutes for urban areas, down about 10 seconds.

Independent crash investigator Hamish Piercy told Mike Hosking police dispatchers act quickly once an emergency comes in.

"That's not to say that the response is slow just because there is a length or delay of calls being answered."

He said part of the problem appears to be a change in system where the 111 line now handles all calls.

"Years ago people used to phone a police station or their local police station directly and they used to handle a lot of calls and it was only those emergency calls that went through to comms centres, now that emphasis seems to have changed."

Police say about half of their calls are not emergencies, and it's planning to divert those calls to another lines.