Abstract Multimedia on wireless networks and the integration with other cellular networks requires support for both mobility and quality of service. When mobile nodes move across different wireless networks, current session may be affected by the several factors like hand off delay, jitter and data loss. Voice over IP (VOIP) will be operated seamlessly across different wireless networks and that resulted few issues like mobility, signals and security. Mobile IP is proposed as a network layer host mobility solution. The problem associated with mobile IP makes it unsuitable for real time interactive solution like Voice over IP (VOIP). In this thesis paper we study the VOIP mobility in homogeneous wireless networks and cross layer mechanism for heterogeneous wireless networks which can support mobility in layer 2 of the network stack to get better VOIP performances and mobility. We describe the cross layer mechanism and the experimental results.