Vodafone is off to court to protest at Telecom's new XT mobile network, in the belief it is the source of interference on the Vodafone network.
Vodafone said it had begun the legal action following a significant rise in the number of customer complaints about interference on its network.
Testing showed serious interference to Vodafone's network caused by Telecom's network, which was still under construction.
Telecom said it would vigorously resist the request for an injunction.
"This is a piece of aggressive behaviour that betrays Vodafone's insecurities about competition from Telecom's new XT mobile network, just 13 days away from the launch," said Telecom chief executive Paul Reynolds.
Telecom said the Ministry for Economic Development had been investigating interference issues between the WCDMA technology used by Telecom and GSM technology used by Vodafone.
It said a letter from the ministry on April 9 said Telecom's WCDMA transmitters meet emission limits specified on spectrum licences.