Mobile phone company 2degrees says the threat of regulation can help spur competition quickly.
The deal reached by the company with Vodafone has prompted the Commerce Commission to decide against an investigation on whether price controls should be imposed on mobile phone providers to use each others networks.
The commission had considered launching a probe into national roaming to ensure new players could compete and expand fairly, but had held off while 2degrees sought an agreement to use Vodafone's national network.
A spokesman for 2degrees, Matthew Bolland says a successful deal allows it to compete, and no investigation is currently needed.
He says it shows the threat of regulation helps commercial negotiation work.
Mr Bolland says a commission decision to extend phone number portability for another six years is another good outcome.