A problem with multicasting

al salamo alikom wa rahmat allah wa barakatoh

 Iam facing a problem in deploying an application, one of the features in this application is recording voice from Cisco IP Phones and save the voice on a file on the hard disk, the problem is that it doesn't work, I have checked the recording in our labs and it works well but at the customer side it didn't work, I've said "It is a security problem" but the company that built the network said that they have no firewall between the IP Phones and the server, so it can't be a security problem.

some one told me that the problem may be in the multicasting on the network, this application use the following algorithm to record the sound :

choose a multicast IP and Port and send them to the IP Phone and order it to send the recorded voice to that IP on that Port and the server go and listen on that IP and Port. 

so if multicasting was closed on the switch, recording will not work.

 But this isnot also the problem, the real problem is that I don't know any way to know exactly where is the problem, the class that i use to listen and save the voice on the hard disk work with events, you register with an object of class with a method called update(Stream) and an object of the Recorder class will call this method when new voice is recieved, so when i try to debug, I don't receive any errors and the method never called.

How can I fix this problem, How can I know if multicasting is closed, How can I switch to UNICAST.

al salamo alikom wa rahmat allah wa barakatoh