—Evolutionary development towards all-IP networks will have various kinds of devices connected to the Internet. In such the ubiquitous networking environment with the features of heterogeneity and ubiquity, the user shall be able to communicate by a best suited way according to his situation and preference. In this paper, a user-oriented session is shown that enables a user to switch devices, media streams, and networks flexibly even during a session. Additionally, protocol adaptation technology is also provided so that various types of devices could be connected to the IMS/MMD networks that are fundamental infrastructures of the all-IP networks. We implemented the proposed system as a prototype using a BREW-enabled mobile phone and MMD core network. Keywords- session mobility; IMS/MMD; SIP; ubiquitous networking