Hundreds of TV licensing workers will stage a 24-hour strike in a dispute over pay, which union leaders said will bring call centres to a standstill.
More than 500 members of the Communication Workers Union (CWU) working on the BBC TV licensing contract at sites in Darwen, Lancashire, and Bristol will take action in protest at a below-inflation wage offer, which the union said followed a two-year pay freeze.
CWU assistant secretary Andy Furey said: "Our members at Capita TV Licensing are facing a pay cut in real terms from a company which makes millions in profit every year."
He continued: "We're asking for a simple improvement in their pay offer which at 2.6% is almost half the rate of inflation.
"The last thing our members want is strikes, but the employer has left people with no choice.
"They are facing increased food, energy and transport bills and work for a company which can afford to reward its staff with fair wages.
"Our members are determined to win a fair deal and if we strike - we strike solid and we strike to win."
Picket lines will be mounted at both sites.