Hi,

VDK is able to handle multiple calls at the same time, either putting them in conference or handling one at a time. The trial version can handle just one call, that is, if you are busy in a conversation you cannot receive any other incoming call nor start another one.

VDK's VirtuaDev technology handles the connection between media sources; incoming audio of a SIP call is a device, speakers another one, wav files another and so on. To write a softphone for example you have to connect microphone to network line and network line to speakers, that is a total of two concurrent VirtuaDev connections. Again, if you want to play an audio file you need to connect the file device to the speakers, that will cost you just one connection. In the trial version the amount of available VirtuaDev connections is 4.

Hope this helps,

regards