Telstra on Friday moved to replace its long-standing head of retail, Gordon Ballantyne, who was seen as a potential chief executive until Andy Penn joined the company in 2012.

Mr Ballantyne, who was responsible for 65 per cent of Telstra's financial year 2015 revenue, quit the company on Wednesday after five years in the job in a move that helped push the telco's share price down despite an overall increase in the S&P/ASX200 index.

But Telstra chief executive Andy Penn used his departure to split Mr Ballantyne's responsibilities into other positions, all of which will report directly to him.

Telstra's consumer and products group managing director Karsten Wildberger​ will now head up Telstra's retail division.

Telstra Media group managing director Joe Pollard will now also become the telco giant's chief marketing officer. Successfully beating rival telcos on the marketing front will be increasingly vital as the national broadband network replaces Telstra's infrastructure to provide all players with the same level playing field.

"Karsten, Cynthia and Joe are outstanding executives who have already made significant contributions to our growth ambitions and will take even larger roles in this new structure. They bring significant international experience prior to joining Telstra," Mr Penn said in a statement.

Telstra would not allow any of the executives to speak with the media.

Ms Whelan previously ran Telstra's strategic finance group and was seen as a front-running candidate in the race to replace Mr Penn as chief financial officer – a role that eventually went to Warwick Bray.

However, in the latest reshuffle she will take on two of Telstra's key growth areas – its push abroad and investments in new businesses such as the high-profile eHealth division, which is expected to make $1 billion in annual revenue by 2020.

Telstra is set to partner with Philippines food and beer giant San Miguel to launch a new mobile network in the country, which Goldman Sachs predicts could cost up to $US3 billion to complete.

Ms Whelan was previously Barclays' Australia and New Zealand chief executive having worked for the bank across the Asian region.

Mr Wildberger is one of the growing number of European-trained senior executives at Telstra and is seen as a solid performer who previously helped run Vodafone Romania – the same company that Vodafone Australia chief executive Inaki Berroeta​ led until coming to Australia in 2014.

Mr Penn has been cleaning house at Telstra as he prepares to grow the company through a range of investments at home and throughout the Asian region.

He recently told Fairfax Media Telstra was willing to slash short and mid-term profit margins in an effort to beat back rising competition and network investments from his rivals, Singtel-Optus and Vodafone Hutchison Australia.

But he faces strong challenges convincing shareholders to let their cash be invested across a range of Asian partnerships and acquisitions.