초록
The major worldwide communication network operators have designed and are building up the NGN with various network capabilities, which conventional Internet do not have. The open network service model makes these network capabilities available to the third party of the value added service providers through the standardized API providing users with more intelligent and enhanced services. This paper proposes the open network service model as NaaS (Network as a Service) and examines service models of several levels. It is believed that these efforts presented in this paper will make the network operators expand their service ranges through the opening of invested network resources producing more various communication services for users.