BT and Openreach workers are to stage fresh strikes in a dispute over pay.
The Communication Workers Union (CWU) said around 40,000 of its members will walk out on August 30 and 31, following two previous strikes.
The August 31 stoppage will coincide with a strike by CWU members in Royal Mail in a separate row over pay and conditions.
CWU general secretary Dave Ward said: “It’s disgraceful that one of the UK’s wealthiest and most profitable businesses is refusing to pay a fair wage to its employees – the women and men whose hard work and dedication contribute so much to this company’s success.
“At a time when inflation is at its highest level in decades, and when this company is returning ever-increasing profits, paying out enormous amounts to shareholders and to its senior executive, it’s totally unacceptable to treat the workforce in this appalling way.
“This is why our members voted to strike in such huge numbers and why they will keep fighting until a fair deal is won.
“As well as the industrial action, this union is making and will continue to make political representations as well – and we warmly welcome every Member of Parliament or local councillor who wants to join us on our picket lines.”
CWU deputy general secretary Andy Kerr said: “Our BT and Openreach members responded magnificently to the first strike call in July and we’re confident they will be every bit as rock-solid in this second bout of action too.
“We remain, as ever, open to negotiations, but in the meantime we are organising and preparing to deploy our pickets all around the UK.
“This union remains a good friend to have and a constructive partner to work with – we continue to urge BT/Openreach to choose that path.
“But if they continue to choose the path of conflict, they will continue to discover that this union is a strong, determined and indefatigable opponent.”