Singapore Telecommunications (SingTel) has revealed that Paul O'Sullivan has stepped down from his role as chief executive officer (CEO) of subsidiary, Optus.

According to SingTel Group CEO, Chua Sock Koong, O'Sullivan "expressed his desire for a change to a non full-time role," and will continue working with Optus as chairman.

The new role will see O'Sullivan continue to advocate the brand, and focus on engagement with key stakeholders in the government and business sectors.

The decision comes after 10 years at the helm of the consumer group, the last two of which were spent in his most recent role.

O'Sullivan has been replaced by Allen Lew, who returns to Optus after having served as CEO of the Digital L!fe group since April 1, 2012, when O'Sullivan was first promoted to his now former role.

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"Allen is returning to Optus where he previously led the consumer and mobile businesses," Chua said. "He is a proven leader who has successfully transformed the Group's Singapore operations as well as built the digital business."

The movement at Optus is part of a SingTel executive shuffle which Chua claims "combines retention of existing management strength and experience with new leadership talent."

Additional changes as part of the new structure include the appointment of Jonathan Auerbach who will take over from Lew at Digital L!fe. Auerbach joins SingTel from McKinsey and Company, where the led the telco, media and technology practice in Asia.

Bill Chang has been appointed Singapore country chief officer, where he will be principal liaison with local and regulatory bodies. Chang will also continue to serve as enterprise group CEO.

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Jeann Low has had her role at SingTel expanded, and will now assume responsibilities for group strategy and general counsel as chief financial officer (CFO).

Lim Cheng, who is currently managing director of the strategic investments group, will adopt the role of deputy CFO, reporting to Low.

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