The objective of this paper is to evaluate the equilibrium price between PSTN and VoIP telephony services in the case of non-linear utility function. Currently there are two types of wired phone service we are known that PSTN (Public Switched Telephone Network) and VoIP (Voice over Internet Protocol). The PSTN telephony which provide high quality service and VoIP which provide relatively low quality service forms a vertically differentiated oligopoly. Therefore, the evaluation of the equilibrium price between PSTN and VoIP services is very important to wired phone service providers. The equilibrium price depends on the state of the service cost function has been proved different value. This paper was evaluated each equilibrium price for the state of the linear cost function and non-linear cost function. Subsequently, analyzed the demand of both services and the equilibrium profit which can maximize the profit of both service providers.

1. 서론
 2. 이론적 배경
  1. 선행연구
  2. 비선형 효용함수
  3. 내쉬 균형 이론
 3. PSTN과 VoIP 서비스 간의 균형가격 도출
  1. 사용자 1인당 서비스 비용이 cqi 인 경우
  2. 사용자 1인당 서비스 비용이 clnqi
인경우
 4. PSTN과 VoIP 서비스 간의 균형가격 비교
  1. 서비스 비용함수가  cqi
인 경우
  2. 서비스 비용함수가 clnqi 인 경우
 5. 결론 및 향후 연구방향
 참고문헌

• 윤상흠(영남대학교, Yeungnam University) | Sang Hum Yoon
• 김향화(영남대학교, Yeungnam University) | Xiang-Hua Jin
• 박종헌(영남대학교, Yeungnam University) | Jong-Heon Park
• 박영준(한국전자통신연구원, Electronics and Telecommunications Research Institute) | Young Jun Park
• 전재호(충주대학교, Chungju National University) | Jaeho Juhn
• 하귀룡(포항공과대학교, POSTECH) | Gui Ryong Ha 교신저자