Call centre staff and engineers from the Communication Workers Union will walk out again saying a recent pay rise is not enough.
Thousands of BT and Openreach workers will go on strike again on Monday in a dispute over pay.
Members of the Communication Workers Union, including call centre workers and engineers, will walk out for 24 hours following action on Friday.
The union will mount picket lines outside company offices across the country and are asking people to bring food which it will deliver to local food banks.
The strike is against a £1,500 pay increase for all employees, which the CWU says means a real terms wage cut because of the soaring rate of inflation.
CWU general secretary Dave Ward said: “Since BT Group workers have been forced to take historic strike action in defence of their standard of living, just like in the pandemic, working-class people will step up to the plate when employers and politicians fail, and are ready to put need before greed.
“We urge all sympathetic members of the public to attend picket lines in their area and chip in to help out others.”
CWU deputy general secretary Andy Kerr said: “On Friday, BT Group workers took strike action and received overwhelming support from the public.
“They showed their strength, but on Monday they will show their generosity.
“When corrupt politicians and overpaid bosses fall way short of the mark, it is working people who look after other working people.
“I have no doubt the public will show their support to workers and struggling families by turning up to picket lines, dropping off goods and standing side by side with people fighting for dignity.”
A BT Group spokesperson said: “At the start of this year, we were in exhaustive discussions with the CWU that lasted for two months, trying hard to reach an agreement on pay.
“When it became clear that we were not going to reach an accord, we took the decision to go ahead with awarding our team members and frontline colleagues the highest pay award in more than 20 years, effective 1st April.
“We have confirmed to the CWU that we won’t be reopening the 2022 pay review, having already made the best award we could.
“We’re balancing the complex and competing demands of our stakeholders and that includes making once-in-a-generation investments to upgrade the country’s broadband and mobile networks, vital for the UK economy and for BT Group’s future – including our people.
“While we respect the choice of our colleagues who are CWU members to strike, we will work to minimise any disruption and keep our customers and the country connected.
“We have tried and tested processes for large-scale colleague absences to minimise any disruption for our customers and these were proved during the pandemic.”
The industrial action will be the latest in a wave of strikes sweeping the country involving union members including railway workers, Post Office staff and refuse collectors.
More strikes are planned in the coming weeks in the bitter rail dispute.