No audio is being played back by IQ.  This is caused by a Message Queueing issue.

CONFIRMING THE ISSUE:

Browse to the logs folder (<install dir>\mitel networks\6160\logs) and open the log file named messagingengine.txt.

If you see the following 2 errors and the customer is experiencing no audio:

3/6/2007 9:50:38 AM   Specified cast is not valid.          (MiTAIPort - PlayMsg)

   STACK:    at System.Messaging.Interop.MessagePropertyVariants.Lock()

   at System.Messaging.Message.Lock()

   at System.Messaging.MessageQueue.SendInternal(Object obj, MessageQueueTransaction internalTransaction, MessageQueueTransactionType transactionType)

   at System.Messaging.MessageQueue.Send(Object obj, String label, MessageQueueTransaction transaction, MessageQueueTransactionType transactionType)

   at System.Messaging.MessageQueue.Send(Object obj, String label)

   at prairieFyre.IQAlarms.CommunicationClient.SendMessage(MessageQueue messageQueue, Object msg, String label)

   at prairieFyre.IQAlarms.CommunicationClient.SendIQAlarm(AlarmInfo alarmInfo)

   at prairieFyre.IQAlarms.CommunicationClient.SetIQAlarm(IQAlarmTypes alarm, String parameter)

   at prairieFyre.IQServices.Common.MiTAI.MiTAIPort.SetupWaveOutDevice()

   at prairieFyre.IQServices.Common.MiTAI.MiTAIPort.PlayMsg(String filename, Int32 delay)

 Error opening wave device 0. Error [ALLOCATED]      (MiTAIPort - SetupWaveOutDevice)

    STACK:    at prairieFyre.IQServices.Common.WaveLib.WaveOut.OpenDevice(Boolean useWaveMapper)

   at prairieFyre.IQServices.Common.WaveLib.WaveOut..ctor(Int32 deviceID, UInt32 bufferCount, UInt32 bufferSize, Boolean useWaveMapper)

   at prairieFyre.IQServices.Common.WaveLib.WaveManager.GetNext(Int32 deviceID)