Restcomm RTP standalone usage

Question

I'm using jain-sip as standalone application. Everything works fine for my purposes. I need to do some modification to my application - play audio file before terminating a call (something like PLAY_ANNOUNCEMENT).
It would be something like this:

    -->INVITE  
    <-- 200 OK  
    <-- Play Audio  
    <-- Terminate call with BYE or CANCEL (depends on dialog state).    

Currently it works without "Play Audio" step.

So my question is: How to use RestComm RTP stack separately from the RestComm MedaiServer?

Some update.

After studying MediaServer sources found that there must be RtpFactory class:

class="org.mobicents.media.server.impl.rtp.RtpFactory"

Found here rtp-beans.xml

But I can't find this class in the sources - RTP source

Any help?