Telkom has issued a notice to cut as many as 3 000 jobs - nearly a third of its workforce - across multiple departments, as the company looks to streamline its operations amid falling earnings and changing market conditions.
Trade union Solidarity, which is one of the unions representing workers, said a notice of the process - which would be conducted in two phases - was received on Wednesday.
"We expected the retrenchments to happens but not in such large numbers. This is quite a large number... we did not expect it," said Linda Senekal, the union's sector coordinator.
She said affected workers include those employed in the IT department, customer services and small business.
With a 9 000-strong workforce, Telkom is adjusting to a shift in operating conditions, which have seen a significant move from voice to data.
The semi-privatised company, which operates in several countries in Africa, has also faced calls by Independent Communications Authority of South Africa to drop data costs.
Senekal voiced concern that the company had opted to lay off workers instead of opting to upskill employees for tech-driven jobs.
"Telkom employs a lot of contractors to do jobs that should be done by its workforce," Senekal said.
The company's interim financial results, released in November, showed that headline earnings dived 36%, while net debt increased by almost R2bn to R11.8bn.
Telkom is among several large organisations considering job cuts as the country battles high unemployment rates and tough economic conditions.
Last year, debt-stricken national airline, SAA, announced plans to reduce head counts, in a move which was fiercely opposed by unions.
This week, MassMart, which owns Game, DionWired and Makro, among others, announced on Monday that it was consulting with its employees about the potential closure of 34 stores. The move could affect up to 1 440 employees.