An application that has just obtained a call may not immediately receive control of the media stream, and may need to wait until the previous owner application relinquishes it. Though this may take time, any application with control of the media stream should transfer control when it sees that a new owner has come on line (the number of owners has increased).
The procedures for transferring control of an active media stream differ for every media-control API. The API may allow only one application to have a media-stream device (such as a COM port used for data transfer) open. In this case, it is important that the current owner relinquish control of a media stream device before handing off the call. But with some other types of media such as WAV audio, several applications (and several devices) can have the media stream open at the same time. This makes it unnecessary to close the media stream before the handoff, and perhaps not at all.