A warning has been issued to those who use emergency locator beacons that they should upgrade to the new 406 megahertz model immediately.
The satellite supporting the old 121.5 and 243 megahertz beacons is being switched off at midnight on Saturday.
From Saturday, the Rescue Coordination Centre in Wellington will no longer respond to distress calls from the old beacons.
The New Zealand Mountain Safety Council says upgrading is a matter of life and death - because the old ones will be useless.
The new beacons are more sophisticated and can send GPS information with precise locations and even phone numbers of emergency contacts.
The devices can be used anywhere in the world and are expected to change the face of search and rescue operations because of the degree of detail.