Increased labour costs and higher tax are expected to see Telkom's headline earnings per share fall by at least 15%.
The company expects improved full year results, with headline earnings per share likely to rise by between 57% and 77%.
A prediction of weaker interim earnings saw the EOH share price fall by almost 21%.
The telco giant swung back to profit for the year ended 31 December 2017, although the strong rand dented revenue growth.
The group's turnaround strategy seems to be working as it reports half year earnings per share after reporting a loss per share a year ago.
The technology services company reported another good set of results due to strong organic growth, complemented by strategic acquisitions.
The group's share price fell over 4.5% after a solid trading statement forecast HEPS growth of between 10% and 20%.?
The group expects headline earnings per share to be between 56% and 66% lower than a year ago.
The company predicts headline earnings per share to rise at least 21% for the year ended 30?June.
The telco is expecting its interim headline earnings per share to swing back into the black.
The global Internet and entertainment group expects core headline earnings per share to be up to 39% higher than a year ago.
Revenue grew to R81 billion as the mobile operator added 5.5 million new customers across its five African operations, with three million of those in SA.