Returning Kiwis who received the police self-isolation check text reported it as a scam because they thought it looked dubious.
And figures reveal only half of the arrivals sent the texts responded, as Commissioner Mike Bush admitted police failed to check on every arrival within three days as promised.
The Government is also coming under mounting pressure to not rely on a voluntary measure and instead quarantine every traveller, despite Prime Minister Jacinda Ardern saying anyone who didn't opt-in would be checked on by police.
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Anyone coming into New Zealand is questioned and those who are symptomatic or don't have a good plan for self-isolation are put in quarantine.
If people are able to self-isolate at home, they should first get a call to check on their welfare then a text from police requesting they share their location.
Appearing in front of Parliament's Epidemic Response Committee today via video link on his last day as Commissioner, Mike Bush revealed there were:
• 116 symptomatic people in quarantine
• 1,573 in hotels under "managed" self-isolation under a 24/7 watch of police and other security
• 4,068 who'd been sent home to self-isolate but it's unclear what timeframe this relates to.
Police had been unable to physically check on everyone in mandatory self-isolation within three days since the borders were closed on March 19, he said.
"In the early days it was very difficult to learn where they were and to ensure that there was compliance," Bush said.
Instead authorities had to create a "technological solution" in the form of a text message which sends a link to a website where travellers can agree to share their location.
In the last 24 hours, Bush said "almost all" of those 4,068 people in self-isolation had received the text and that they would also randomly be checked on in person.
A police spokesperson later told the Herald that 6,250 texts had been sent since Monday and "over" 3,000 people responded.
Anyone who didn't agree would be followed up with a check by police, said Bush.
The text from 4511 reads: "NZPolice COVID19 self-isolation check under S.70(1)(f) Health Act 1956. Select the link to confirm location."
But Aucklander Stuart Marshall, who returned from Japan with his wife and child on Monday, said he almost disregarded the text from a random number as a scam.
A friend reported it to cyber security agency CERT.
CERT manager of Operations Declan Ingram told the Herald they'd received a small number of reports - fewer than 10 - about the isolation check text. All were investigated and confirmed that messages they'd received were legitimate.
After being assured it was real, Marshall followed the link and permitted his location being tracked but said the site itself didn't appear very legitimate.
"It's a pretty bare bones website but they've probably not had much time to work on it."
Another woman who also came back to New Zealand on Monday said she got a text at 9.30pm while she was half asleep.
Seeing the random number and the link, she researched the text and found a little information on the police website that new arrivals may receive a text.
"It gave me a bit of a sleepless night as I did not know what was expected of me to do and also if my phone was hacked.
"None of my friends who'd recently returned home nor my partner isolating with me had received that message."
After calling Healthline and learning it was legitimate, she followed the link, agreed to share her location and then was asked to share a photo.
"It is really confusing. I still don't know what is expected of me. I was not asked to consent to continuous tracking, so I am unsure what this is meant to achieve."
Opposition leader Simon Bridges, who chairs the Committee, told Bush the fact police hadn't checked on all arrivals "just isn't good enough".
Bush replied: "I agree with you. It is really important and it was our intent but what we had here was a systems issue to get all that information from the border to our frontline staff."
"I think you'll all agree that it is unprecedented, it is unique and you have to build robust systems and processes from the ground up.
"So there has been no shortage of effort by everyone involved to get this right."
Bridges said later the third day of the Epidemic Response Committee showed how disconnected the three key agencies - Health, Police and Customs - were in enforcing self-isolation.
"Effective quarantining has been the foundation of other countries' successful responses. Here in New Zealand we've been waving people through and trusting them to self-isolate.
"Today's questioning has raised serious concerns about how well this lockdown is being policed and shows exactly why we need to be quarantining at the border.
"New Zealanders are sacrificing a lot right now, the key agencies involved in the response need to ensure they aren't leaving the barn door wide open."
Ardern said there was a "level of reliance" on all New Zealanders to follow the rules and pointed out that anyone who was symptomatic was quarantined – "not put in a hotel, quarantined".
The Prime Minister said she understood most people opted in to sharing their location.
Testing at border could mean relaxed isolation
Customs Minister Jenny Salesa also appeared before the committee and said the procedures at the border were a direct response to advice from Public Health officials.
If everyone coming through was tested and temperature tested and the results were negative, there was a concern people would then be relaxed about self-isolating, Salesa said.
Customs and police officers now meet travellers at the aircraft door, escort them in small groups and follow markings on the floor to ensure 2m distancing as they came to the health screening area, Salesa said.
Health staff then further questioned travellers to determine who should be in quarantine or self-isolation.
Anyone who was symptomatic was escorted into quarantine in a hotel or a hospital, if required.
Comptroller of NZ Customs Service Christine Stevenson said everyone coming into the country had their arrival cards scanned and that was sent to Healthline and police immediately.
BEST OF BUSH ON HIS LAST DAY AS COMMISSIONER
On the last year:
"We're truly in unprecedented time. Never in my 42 years policing career have I ever experienced a year like the last twelve months."
On Simon Bridges driving about 18km to the beach.
"The short answer to that is, no."
Ashley Bloomfield on Bush's leaving do:
"There won't be a party at Mike's place later."
"There'll be a virtual one," said Bush.
On the self-isolation police texts:
"It's always a bit dangerous when someone like myself [gets involved] who doesn't have a deep understanding of technology but knows what it can do."