Tony van Marken has resigned as CEO of Vox Telecom, effective 31 March, "to pursue personal interests", the company says.
MD Doug Reed will take over Van Marken's responsibilities, assisted by the executive management committee.
Vox Telecom is an alternative telecommunications company and has been in the market for more than 10 years with DataPro Internet, Orion Telecoms, and Atlantic Internet.
The company has grown organically and through strategic acquisitions, and is listed on the JSE with a market cap of 2.5-billion.
During his career, Van Marken has been a high-tech entrepreneur, management consultant, venture capitalist and independent director in South Africa, the UK, Canada and France.
He joined the board of Vox Telecom in July 2006 as a non-executive director and was appointed executive chairman in November of 2006. In September 2009 he was appointed CEO.