In my Session_ConnectCompleted event I have code that looks like the below: var attrs = new List<string> {InteractionAttributeName.State}; this.InteractionQueue.StartWatching(attrs.ToArray()); and later on I check state in various places, for example: public bool IsOnCall { get { var onCall = (null != this.PhoneSession && null != this.CallInteraction && this.PhoneSession.ConnectionState == ConnectionState.Up && this.CallInteraction.State != InteractionState.ExternalDisconnect && this.CallInteraction.State != InteractionState.InternalDisconnect); return onCall; } } Sometimes and it seems sporadic, I get the below exception doing this: Exception outermost view of call stack -------------------------------------------------------------------------------- Exception type: ININ.IceLib.NotCachedException Source: ININ.IceLib.Interactions Source Assembly: ININ.IceLib.Interactions.DLL Source Assembly Version: 0.0.0.0 Source Type: ININ.IceLib.Interactions.WatchedAttributeCache Source Method: System.String GetAttributeAsString(System.String) Debug Build?: True Message: The requested object or attribute is not being watched. Name: Eic_State Stack Trace: at ININ.IceLib.Interactions.WatchedAttributeCache.GetAttributeAsString(String name) at ININ.IceLib.Interactions.Interaction.GetWatchedStringAttribute(String attributeName) at ININ.IceLib.Interactions.Interaction.get_State() at TeamWorks.Shared.CTI.PhoneAgent.get_IsOnCall() at TeamWorks.Shared.CTI.PhoneAgent.Call(DialInfo dialInfo) I'm already watching State and there is no EIC State attribute as far as I can see. Any ideas on what might be causing this and how to resolve? Thanks

Any chance this is in a method that is being called from an event? If so, you may be on the wrong thread when the call comes back.

At the point of the crash, no. I thought it might be a threading issue at first but it appeared to be on the same thread and when I checked IsWatching(attributeName) it said true at the point of the exception. The crash would appear to happen at random after several different connects/disconnects and various phone operations over time. In any event I changed the code to save the state property to a variable anytime it changed. The code then checks the variable instead of Interaction.State (in theory they should always be in sync).

If I were to add this back or monitor other attributes, how would I handle watching attributes on both threads? Currently I call StartWatching in the Session_ConnectCompleted event which I would assume would be back on the main UI thread from which the session was kicked off from?

It should be on the correct thread, but there is and easy way to check. If (InvokeRequired) { blah blah blah } If it takes the InvokeRequired path then that means it came back on a thread other than the main thread.

Yeah I already have the proper InvokeRequired checked in there at least for the UI control portion. However the main class is not a Control so InvokeRequired doesn't work and I have to use SynchronizationContext. My question was more to the effect of if I wire up InteractionQueue_InteractionChanged on the main UI thread will that fire regardless of whether the change happened using an IceLib Async or Sync method/event? Something still seems up though because before the exact same steps would work for a while then suddenly not over time. Almost as if something times out/ goes out of scope etc. Is there a way to perhaps write the code defensively in such a way to ensure the attribute is watched / available no matter what?

As long as the InteractionChanged event comes back on the gui thread you should be ok. I don't know of any way to code it defensively, but here's how I have my InteractionChanged event coded. _myInteractions.InteractionChanged += new EventHandler<InteractionAttributesEventArgs>(_myInteractions_InteractionChanged); void _myInteractions_InteractionChanged(object sender, InteractionAttributesEventArgs e) { if (this.InvokeRequired) { this.BeginInvoke(new EventHandler<InteractionAttributesEventArgs>(_myInteractions_InteractionChanged), new object[] { sender, e }); } else { updateMyInteractionsList(e.Interaction); if (lvMyInteractions.SelectedItems.Count > 0) { if (lvMyInteractions.SelectedItems[0].Name == e.Interaction.InteractionId.ToString()) { updateCallControlButtons(e.Interaction); } } } }