Competition is helping slash the price of cellphone calls, with Callplus the latest company to enter the market.
The two biggest operators, Telecom and Vodafone, are keen to persuade the Commerce Comission that prices are falling - in a bid to stave off regulation to force prices down.
Callplus has about 150,000 phone and internet customers who can now sign up for mobile services as well.
Pricing is typical of the mobile market: customers who sign up for longer get cheaper calls and the more services they buy, the better the deals.
Prices are as low as 25 cents per minute for some plans. Callplus does not have a mobile network, but will instead buy wholesale services from Vodafone.
Callplus will be a competitor, but Vodafone benefits from income generated by its wholesaling contract.
Vodafone has similar deals with Telstra Clear and the internet service provider, Orcon.
It says there wil be other deals which will dramatically expand the number of mobile operators.
The move by Callplus into the market follows the launch in July of the country's third mobile operator, 2 Degrees.
The company offers flat-rate pre-pay deals which slash some pre-pay costs from as high as 89 cents a minute to 44 cents.
Some deals price mobile calls as low as 21 cents a minute, while Telecom's XT network has helped change charging practices, by pricing to the second, and not rounding up to the minute - a considerable price saving.
Vodafone says the price of calls is falling by up to 20% a year.
Prices still to high: Consumer NZ
But Consumer New Zealand chief executive Sue Chetwin says they are still too high.
2 Degrees has lobbied for the axing of mobile termination rates - that's the price subscribers of one network pay to place calls to people on another network. That's about 15 cents a minute.
The Commerce Commission believes those rates are twice what they should be and Ms Chetwin says cutting those costs would mean significantly cheaper cellphone bills.
In a draft decision in June, the Commerce Commission recommended regulation to force down these rates.
Mobile operators have been trimming prices since in a bid to stop that happening.
In their final submissions, both Vodafone and Telecom offered to cut these rates further, in Telecom's case by almost 25%.
The Commerce Commission will make its final recommendation in December.