Recently, the Internet has become the most important vehicle for global information delivery. As consumers have become increasingly mobile in the recent years, introduction of mobile/wireless systems such as 3G and WLAN has driven the Internet into new markets to support mobile users. This chapter is focused not only on QoS support for multimedia streaming but also dynamic session management for VoIP applications: As the types of user devices become diverse, mobile networks are prone to be "heterogeneous." Thus, how to effectively deliver different quality levels of content to a group of users who request different QoS streams is quite challenging. On the other hand, mobile users utilizing VoIP services in radio networks are prone to transient loss of network connectivity. Disconnected VoIP sessions should be effectively detected without introducing heavy signaling traffic. To deal with the above two issues, an efficient multimedia broadcasting/multicasting approach is introduced to provide different levels of QoS, and a dynamic session refreshing approach is proposed for the management of disconnected VoIP sessions.