Nine out of ten New Zealanders received the latest emergency nationwide test alert on their cellphones from the National Emergency Management Agency (NEMA).
The mobile alert is one way to communicate to people when their life, health or property is in serious danger.
NEMA director John Price told Morning Report that Sunday evening's alert was a success, not just for testing the emergency system, but for the community to be able to have a conversation about what they need to do if there is an emergency.
Price said it reached about 90 percent of New Zealand cellphones.
"We have an annual survey each year, and that survey gives us an indication that nine out of ten cellphones it hit off.
"We also work with the telco providers and they indicate to us through the cell towers that that's the sort of hit rate.
"Ninety percent of the coverage area was covered, and nine out of ten New Zealanders received it."
Price said that some parallel imported phones and older phones that haven't been updated might not have received the alert.
He also stressed the importance of not relying just on the cellphone alert as a warning system.
"These tests that we do, and these mobile alerts are very, very important, but it's only one form of notification."
The other notification system that is used during emergency situations is radio.
"We rely on radio as one of the most highly picked up notification capabilities, the use of radio is very important to us, the use of the internet is also important.
"But the most important one is the human notification. If you experience something, e.g. an earthquake or the waters are rising, that's the first thing that people must do, don't wait for the authorities to tell you to do something, do it yourself."
Price acknowledged there were problems and confusion during recent weather events, but said NEMA was working to put in place recommendations that have been brought up in reviews into the response to Cyclone Gabrielle and the Auckland Anniversary Floods.
RNZ is New Zealand's statutory civil defence lifeline radio broadcaster, providing vital information and updates as they come to hand. Check out the frequencies here. NEMA advises that in times of crisis or civil defence emergency a battery powered radio or a car radio remain essential lifelines if power is out and other forms of communication are unavailable.