Johannesburg - New call termination rates proposed by Icasa were declared invalid and unlawful by the High Court in Johannesburg on Monday, eNCA reported.
As a result, it would cost less from Tuesday to make calls between different cellphone networks.
The court gave the Independent Communications Authority of SA (Icasa) six months to amend its regulations.
MTN and Vodacom had taken Icasa to court on an urgent basis to stop it from implementing a regulation on mobile termination rates. These are the rates operators pay one another for calls to other networks.