Abstract: An integrated voice and data application delivery system that can deliver converged voice/data application services to at least one user device over at least one communications network, and optimize the delivery of voice/data content during a current voice/data session based on the bandwidth of the network and/or the capacity of the user device. The integrated application delivery system allows users to switch from one voice/data session to another in response to a predetermined event, as required to avoid a loss of information or a permanent interruption of service. The integrated voice and data application delivery system includes a unified XML-based integrated voice and data media converging switch, a controller coupled to the switch, and a data storage device coupled to the controller. The switch transfers voice/data content between voice/data applications on a first network and one or more user devices on a second network.