Enabling mobility in IP networks is an important issue for making use of the many light-weight devices appearing at the market. The IP mobility support being standardized in the IETF uses tunnelling of IP packets from a Home Agent to a Foreign Agent to make the mobility transparent to the higher layer. There are a number of problems associated with Mobile IP, such as triangular routing, each host needing a home IP address, tunnelling management, etc. In this paper, we propose to use mobility support in the application layer protocol SIP where applicable, in order to support real-time communication in a more efficient way.