Problem of EMS

[Nigan]

Hello everyone,,
Installed EMS on cutomer site. Program loaded on computer with mp3 file and streaming to port 32686 on their epygi. EMS shows that it is streaming, but don't hear anything when call placed on hold. RTP Streaming channel and EMS port match, Tried pointing EMS to both external IP of the PBX and Internal IP, same result. Is there any other settings either on the computer, or perhaps the firewall ( not useing epygi firewal) that could be blocking the stream?
Computer has windows XP OS