Grumpy Kiwis have become the targets of late-night hoax calls that ring and hang up when answered.
Thousands of calls, many of them between midnight and 4am on Tuesday, have taken place across the country, prompting phone companies to warn against trying to return the calls.
The callers have phoned landline numbers from a hidden number, believed to have originated from offshore.
Spark New Zealand communications adviser Lydia Tebbutt told NZME the calls could be a scam.
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"Spark would like to assure customers that there has been no security breach and we would encourage any customers who receive calls of this nature not to phone the number back."
Vodafone was not aware of this particular incident, but saw calls of this type made before Christmas.
"These types of scams usually present as international numbers," spokeswoman Alice Paine told NZME. "However, it can also happen when international call presents on the phone as a local New Zealand number a tactic known as call ID spoofing."