More than 100 Telecom service workers in Auckland say they will continue to strike until Monday, when they hope to be joined by about 1000 workers in a nationwide stoppage.
The Auckland technicians are among 900 workers the Australian company Visionstream wants to hire as owner-operators.
The Engineering, Printing and Manufacturing Union says workers in Northland, Wellington and Canterbury - another 280 engineers - have also agreed to take action in the next couple of weeks. And the union says it is likely engineers on the West Coast and in Nelson and Blenheim will follow suit.
Union organiser Joe Gallagher says the 100 technicians cover about a quarter of the one million phone lines on Auckland's North Shore.
Telecom's network arm, Chorus, says North Shore customers may experience delays with services being installed, but faults are being prioritised.
Northland Telecom engineers say their two-day strike next week could cause havoc if a major fault develops. The 70 workers who fix phone and broadband faults, will strike next Monday and Tuesday.
Denis Collier, a Whangarei Telecom worker, says the engineers don't want to inconvenience the public but feel they have no choice but to strike. He says the biggest risk is that a digger could slice through a fibre optic cable, a common event in the rural north.
Visionstream says the engineers may be getting misleading information about the deal they've been offered. Chief executive Andrew Stevens says individual contracts will be open-ended, not for 12 months as many believe, and the workers will earn more, not less.