"When the sun goes down, I'll kill you," Michael Walter Toa told his victim.
She had come home on February 26 to find Toa drunk in her house, demanding to use her phone.
But Toa became agitated when the victim said she had no credit on her phone.
He continued to become "increasingly agitated", eventually threatening to kill her, Judge David Cameron said in Whanganui District Court on Tuesday.
The victim said she did not like it when Toa made "threats like that", and that she would go to her mother's house and call the police.
"Maybe I should beat you up and smash the place up," he said in response.
The victim then left and contacted police.
Toa has pleaded guilty to behaving threateningly.
Judge Cameron noted he had previous violence-related convictions, including breaching a protection order.
He sentenced Toa to a month in prison.
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