ithout extra protocol conversions and gateways, allowing such a scenario to be easily realized. Integration of VoIP (Voice-over-Internet Protocol) applications and home network applications: In the near future, VoIP appliances and home appliances will co-exist at home. For example, a video conversation might be recorded using a VoIP video telephone and the video con- versation watched at a later time. In this situation, it would be useful for a user to be able to control the video conversation in the same way as ordinary video streams arriving via TV or DVD are controlled. There are several reports of research in which home network systems have been implemented with SIP. Bushmitch et al. extends the OSGi framework for handling SIP device facilities to support interoperability with mobile devices [6]. A novel architecture for the mobile OSGi architecture based on SIP functionalities is described In [7]. In [8], a multimedia service framework is proposed, which defines communication protocols to adjust A/V rendering among a media server, a home server, and A/V devices. Our work comple- ments the research detailed in these papers. This paper is organized as follows. In Section 7.2 and Section 7.3 we briefly present the UPnP and the related SIP specifications, respectively. We overview issues in redesigning the UPnP functionalities with the SIP in Section 7.4. In Section 7.5, we describe how the discovery in UPnP may be realized in the SIP functionalities. Section 7.6 briefs its implementation. 7.2 UPnP We describe the functionalities of UPnP based on [2, 9]. A UPnP network consists of communicating devices. Some devices, known as control points, can access and control other devices, which may offer any number of services. A device may be root or may contain other devices embedded within it. A root or embedded device provides services to a user and other devices. For short, both are called "devices" in the paper. A control point and a device are depicted in Figure 7.1. A service is modeled by state variables and acti