Contact your firewall administrator to find out what server (or host) the proxy is on and what port number the proxy is listening on. Then you can configure RealAudio Player to work with the proxy by editing the proxy preferences:
To configure RealAudio Player for a single UDP port:
Continue to Generic Packet-Filtering Firewalls
Receiving UDP Through a Single Port
The UDP option in RealAudio Player can offer better sound quality than TCP-only on
slower connections, so TCP-only may not be desirable.
RealAudio Player 2.0 and later also offers the ability to limit Players inside some firewalls to
receive UDP on only one port, which makes router configuration
easier than allowing the RealAudio Player 1.0 protocol UDP port range.