Telecom and Vodafone are in a High Court scrap over an allegedly misleading ad campaign.
Telecom, the country's biggest phone company, is claiming aspects of Vodafone's new "SuperNet" advertising is misleading to consumers and a breach of the Fair Trading Act.
Telecom wants the campaign changed or pulled and has filed an injunction in the High Court.
The advertising describes Vodafone's infrastructure "as the best fixed-line network".
The Weekend Herald understands Telecom also takes issue with Vodafone calling its cable network in Wellington and Christchurch "ultra-fast broadband".
This network was previously owned by TelstraClear, which Vodafone bought last year.
Yesterday afternoon Vodafone issued a statement saying it would defend the campaign: "We stand behind the Vodafone SuperNet campaign.
"We are confident in what we are communicating and we will be defending Vodafone SuperNet in court."
A High Court telephone conference took place yesterday afternoon where it is understood timetabling for the case was discussed.
Last night the Vodafone Super-Net ad campaign was still active online.
In November last year Vodafone was fined $960,000 for what was the latest in a string of misleading advertising prosecutions brought by the Commerce Commission.
The 21 charges related to claims made by Vodafone regarding the extent of the coverage of its wireless broadband network, made in the "broadband everywhere" campaign.
Telecom admitted breaching the Fair Trading Act after misleading customers about the amount of broadband data they had used.
It reached a settlement with the Commerce Commission over the breach, which came about when inaccurate readings were used for around 97,000 customer accounts between November 2010 and June 2011 - caused by a software fault in its meters.
This story has been changed from a previous version which incorrectly said Vodafone admitted breaching the Fair Trading Act after making inaccurate meter readings. This was in fact Telecom.