Lifeline has refused help from another helpline provider, even though it's struggling to cope with the volume of calls it's getting.
Last week, Lifeline launched a new fundraising campaign, saying a lack of money meant it wasn't able to answer one in four calls.
Homecare Medical gets government funding to operate a number of health, depression, and counselling helplines, known as the national telehealth service.
It said it had offered support to Lifeline multiple times over the last three years, when its call demand outstripped resources.
Homecare Medical chief executive, Andrew Slater, said that to date that offer hadn't been taken up.
"Part of our work is to support the entire health system in responding to New Zealanders' needs. This includes supporting other helplines in their work. This includes advice on technology, sharing operational policy and procedures and during times of peak demand, supporting them when they can't respond to their demand," he said.
Homecare Medical remained willing to work with Lifeline to find a solution to ensure all calls were answered, he said.
Lifeline wouldn't say why it hadn't taken up the offer.
It said its discussions with Homecare Medical were ongoing.
In 2015, Homecare Medical won the contract to operate the National Telehealth Service.
The 24/7 free helplines it operates include Healthline, Quitline, 1737 Need to Talk?, and the Depression Helpline.
Lifeline is part of Presbyterian Support Northern. It does not receive Government funding.
Lifeline declined a request for an interview.