JMF internal UDP Socket, RTP streaming

Question

I am working on a Videostreaming app which streams videos from Android to a JMF server. My JMF server app is based on this sample code:

http://java.sun.com/javase/technologies/desktop/media/jmf/2.1.1/solutions/AVReceive2.java

I've implemented the RTP on the android and I send the rtp packets via UDP to the address where my JMF server runs. But the problem is that the rtp packets don't arrive and the only Idea I got is that there is no UDP Socket, or at least one does not have access to it.

Is JMF running a UDPSocket which receives RTP packets? And if so how can I access it? The whole RTP Streaming thing is done via a receivestreamlistener and the RTPManager.

The reason why I am using JMF is that it provides an API which can plays videostreams and I don't want to reinvent the wheel.