TENET holds electronic communications licenses from ICASA that allow it to build and operate electronic communications networks, including optical fibre networks, and to provide electronic communications services to South African universities, science councils and associated support institutions.
Greaves will be taking over the reigns from Duncan Marti, who is retiring after serving as Chief Executive for 12 years, on January 1.
On his appointment Greaves said: "I'm honoured to lead TENET in the next phase of its development.
"TENET will maintain and strengthen its service levels, while continuing to work with all stakeholders to ensure the fitness for purpose of South Africa's national research and education network."
Greaves joined TENET in 2003 from his position as IT Director at the University of Natal.
To ensure a smooth transition and handover, Martin will remain at TENET until January 31, 2013.
TENET runs a 10 Gbps circuit to London on the SEACOM cable system, redundant backhaul circuits from the SEACOM landing station in Mtunzini, the SANReN 10 Gbps backbone, SANReN fibre rings in Johannesburg, Pretoria, Cape Town and Durban, the GEN3 MPLS network and Metro-E circuits provided by Neotel, IP Connect bandwidth into the ADSL cloud, and various optical fibre and wireless access circuits.
It also operates transit and peering links in Cape Town, Johannesburg, London and Amsterdam, including a connection to the European research and education network, GÉANT.