In an ongoing salary dispute with the telecoms firm, thousands of BT and Openreach employees conducted new strike action on Tuesday.
More than 40,000 members of the Communication Workers Union (CWU) are reportedly striking today and on Wednesday.
It occurs at the same time as additional strikes at Royal Mail, where 115,000 CWU members are scheduled to strike on August 31.
Separately, big unions are stepping up their demands for improved compensation and are attempting to coordinate strike action this fall.
Before the Trade Union Congress next month, Unite and Unison have presented motions calling for future walkouts to be coordinated.
It comes after a wave of strikes that affected a variety of industries in the UK, including those involving rail employees, attorneys, and trash collectors.
According to the CWU, its members are on strike because BT Group has promised them a £1,500 wage raise. According to CWU general secretary Dave Ward, "the cause of the strike is straightforward: employees will not accept a dramatic decline in their living standards."
According to BT Group, the offer offered the greatest pay raise in more than 20 years, with an average increase of about 5% that increased to 8% for the lowest paid.
However, Mr. Ward noted that "this is a substantial real-term wage drop in the context of Retail Price Index inflation levels already exceeding 11.7% this year."
Additionally, Royal Mail postal workers will resume their strike on Wednesday and hold two more days of industrial action on September 8 and 9.
The future of Royal Mail is more dubious than at any other point in its lengthy existence, according to a spokesperson for the company, due to the CWU's self-centered actions with the larger trade union movement.
The representative continued, "The CWU is evading to avoid discussing the reforms we need to make as a business."
The CWU has been contacted by the BBC for a reply.
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