Covid-19 coronavirus: That shrill beep alert might only be dodged if you're in the bush

The shrieking of phones with the Covid-19 emergency alert this weekend was absent from some stretches of rural New Zealand.

But people returning from bucolic adventures might have had a special surprise when stepping back into cellphone reception areas.

Phone users outside coverage areas don't get the alerts.

Millions of people got the latest Covid-19 emergency mobile alert but those outside coverage areas probably weren't suddenly reaching for their phones like many others. Photo / 123RF

Civil defence authorities said other methods could be used to reach Kiwis in remote areas.

A National Emergency Management Agency (NEMA) spokesman said information was distributed on TV, radio, other media, social media and websites.

"If you live or are visiting somewhere that doesn't have mobile coverage, then we encourage you to consider other channels through which you can stay informed."

He said people could also ask local Civil Defence Emergency Management Groups about available alerting channels in their areas.

The agency said alerts were also available in an open-source format, so could be disseminated on channels including third party apps, using the internet.

The emergency mobile alert or EMA on Saturday night described Auckland's move to alert level 3 and the rest of the country's jump to level 2.

In 2019, 70 per cent of New Zealanders got the alert when the system was last tested.

That equated to about 80 per cent of everybody who had a mobile phone then.

"These numbers are higher when you count people who didn't receive the alert but were near somebody who did," the NEMA spokesman added.

He said more people would be getting the latest alerts as the technology became more freely available and people replaced old phones.

NEMA said overseas experience showed at 70 per cent penetration, a critical mass was achieved where word spread to the vast majority of people.

Some of those who didn't get to share in Saturday night's alert experience didn't miss out entirely.

If people move back into coverage when the emergency mobile alert broadcast is live, they get the alert.

The live period can vary according to the emergency or hazard but ranges of 1 to 12 hours have been used before.

Spark's 3G (left) and 4G coverage areas. Photo / Spark

Cellphone coverage varies between service providers and networks but Spark said its 3G network reached 97.5 per cent of New Zealanders.

A scheduled test of the alert system was cancelled last year in light of potential confusion due to the Covid-19 pandemic.

A 2019 Colmar Brunton survey found 80 per cent of mobile phone users believed the EMA was effective at alerting people in an emergency.

And 82 per cent of mobile users then said New Zealanders should not be able to opt out of the EMA system.

Only police, NEMA, the fire service, the health and primary industries ministries, and Local Civil Defence Emergency Management Groups can issue alerts.