The Ministry of Health says the Healthline call centre is overloaded with people who are making general enquiries about COVID-19 instead of using the service "as it's intended".
The ministry's Director-General Dr Ashley Bloomfield admitted on Sunday that Healthline isn't keeping up with all the calls and urged only those who need to contact them to do so.
"Healthline is overloaded... What I would say to everybody is remember that Healthline is there to give health advice, it is not there to give general advice about COVID-19."
He says general information on the virus is freely available on both the COVID-19 and the Ministry of Health's websites.
If people use Healthline "as it's intended", Dr Bloomfield says there is sufficient capacity to deal with all the calls.
"So just a plea to everybody to use it for what it's there for. Anyone who needs to self-register can do that online, they don't need to ring Healthline to do that."
Many people have said they've had trouble contacting Healthline, including a person in Taupō who was the first in the city to contract the virus. He claims he couldn't get through for four days.
He took to Twitter to ask the Ministry of Health to return his calls, but he didn't get a reply and eventually contacted Taupō Health Centre instead.
"Big ups to #TaupoHealthCare for going out of their way, doing a #Coronavirus swab test," he posted.
He had returned from overseas travel on March 12 and has been in isolation since March 14.