A head end apparatus is used in a VoIP (voice over Internet protocol) network providing a VoIP service to subscribers by using an MGCP (media gateway control protocol, the VoIP network employing data communication terminals together with VoIP terminals. The head end apparatus allows the VoIP network to provide data communication service as well as VoIP service to the subscribers by minimizing lack of authorized IP (Internet protocol) addresses. The head end apparatus having an MGCP network address translator (NAT) router establishes a second path for VoIP communication between a VoIP terminal and an IP (Internet protocol) network which is separated from a first path for data communication established between a data communication terminal and the IP network by a contemporary router.