We are developing a Voice over Internet Protocol (VoIP) application and We are facing call disconnect issue when making GSM call when you are already on outgoing call (Voip app call).

1. Make an outgoing call from VoIP Application and wait until call is connected.
2. Put application in background and try to make a GSM outgoing call

After step 2, "Call Failed" dialog appears and both the VoIP app call and the outgoing GSM calls are disconnected
 


This issue got fixed with passing dateConnected parameter as null [provider.ReportConnectedOutgoingCall(new NSUuid(call.UUID), null)].

In case of issue reproducible, provider.ReportConnectedOutgoingCall's dateConnected parameter is supplied like  provider.ReportConnectedOutgoingCall(new NSUuid(call.UUID), Tools.ConvertDateTimeToNSDate(call.ConnectedOn));


 
We are not able to identify how passing dateConnected parameter as null is fixing this issue. We could not able to find any reference. Please help on this detail..