The fine followed a decade-long investigation into the telecommunications company's practices.
The case began in 2002, with internet service providers alleging Telkom charged its competitors high prices for using its services, while charging much lower fees to its subsidiaries and its customers.
AP reports the government still owns part of Telkom SA Ltd, once an entirely state-run
company.
The company, with operations in other African nations, has had financial troubles in recent years. Subscribers also have increasingly dropped fixed telephone lines, the backbone of Telkom's business, for mobile phones.
Telkom shares dropped more than 3% in Tuesday midmorning trade on
the JSE before recovering.
Half of the penalty is to be paid within six months of the tribunal's decision, while the balance is payable within 12 months thereafter.
At 10:19‚ the share price was down 16c to R17.89‚ off the session lows of R17.19.*Follow Fin24 on Twitter, Facebook and Google+.