The spread of ubiquitous communications is dramatically changing the way of daily work. Office workers can now deepen mutual understanding by using a telephone and a PC concurrently [1]. In this paper, we present an ad-hoc endpoint pairing method that enables a user to easily establish a pair of endpoints, such as an IP-hard phone (fixed or mobile IP-phone) and a PC-based soft phone, simply by simultaneously clicking a GUI button on the display screen of each endpoint. Using the endpoint pairing information, the user can easily launch a PC-to-PC web/data conferencing application during a phone-to-phone audio conversation. It can thus promote deeper mutual understanding between users.