Multimedia applications have been the key driving force in converging fixed, mobile and IP networks. A major hurdle in the realisation of this convergence is obtaining Quality of Service from a heterogeneous, best-effort service network. Interactive voice requires strict bounds on delay, jitter and packet losses, video adds significant bandwidth requirements to the network, while internet only makes its best effort to deliver a packet. Hence, the end-to-end QoS management of heterogeneous networks supporting multimedia services is of paramount importance. This paper presents a performance study of multimedia applications over 802.11 networks within metropolitan area networking environment. Specifically, we study QoS performance of VoIP applications over 802.11, while sharing the network resources with HTTP and video applications. Using the OPNET simulator, we simulate a number of realistic application traffic scenarios and study the network performance by analysing QoS parameters including delay, jitter, MOS, and packet loss ratio.