About 100 workers angry at the prospect of losing their jobs protested loudly at Telecom House in Auckland on Friday.
Telecom's network arm, Chorus, has awarded maintenance contracts to Australian company, VisionStream.
The contract will see the majority of Chorus workers forced to become owner-operators over the next three months.
The Engineering, Printing and Manufacturing Union says up to 900 telecommunications engineers in Auckland and Northland will have to buy their own equipment, including vehicles, and some may be forced to quit.
Union delegate Peter Kelly says the protest was a warning shot to Telecom and workers want a chance to negotiate.
A spokesperson for Chorus, Robin Kelly, says the contract allocation reflects the changing telecommunications industry.
Mr Kelly says the workers should contact Vision-Stream if they want more information about the contract.
