Staff have voted to take "whatever industrial action necessary" to prevent the closure of a Midland Marconi plant.
Officials, with the union Amicus, say the resolution was passed by 160 votes to one by members at Coventry's New Horizon Park works yesterday.
An Amicus spokesman said the decision would be on the table when officials meet with management tomorrow.
Marconi has announced plans to close the New Horizon Park Plant with the loss of 180 jobs and a further 270 are earmarked to go at Coventry's New Century Park plant which employs over 1,000 people. Union officials expect to learn tomorrow in which areas those posts would go.
The announcement last week came as 800 jobs nationally were earmarked to be lost following a decision by BT to award a major contract to oversees companies.
It has confirmed the New Horizon Park jobs would be transferred to Italy.