In 2000 Telkom claimed more than R2.6bn from the American-based Telcordia Technologies in a dispute over a software contract.
Telcordia responded with a damages claim of more than R1bn.
On Wednesday the Supreme Court of Appeal (SCA) upheld an appeal by Telcordia against an order by the Pretoria High Court in favour of Telkom SA Ltd, setting aside an international arbitration award.
The high court at the time set aside the arbitration award, removed the arbitrator (a British advocate) and appointed three new arbitrators, all retired South African judges, instead.
However, the SCA upheld Telcordia's appeal and set aside the high court order.
The SCA ordered that Telkom's application (originally in the high court) be dismissed with costs.