When the complaint comes in that the MWI is not synced with the in-box, I assume there is a new VM message in VMO, but the light is out. If that is correct, at that point, I would check the subscriber page under "Messages". There is a section called "Message Waiting Indicators". Check the status there. Depending upon what the status is, a different direction for troubleshooting will take place. I'd bet that the Unity status says the light is on, but it isn't.
This status is Unity's "belief" of the state of the MWI based on a few things: 1)Unity's recognition of a new, unread voice mail message for the subscriber and 2)a successful MWI delivery.
I think that we can assume #1 is correct since the new message is showing up in the in-box. We have to define what "successful MWI delivery" means here. In your Intecom case, it's pretty simple (and at the very lowest level): did the function to request an out-bound MWI serial packet out the RS-232 port succeed? That's all Unity has to base success. There is no acking/nacking from the PBX (that's just how SMDI is). If the PBX is acking/nacking, then it's not traditional SMDI anyway.
Does this mean the PBX actually received the MWI request? Well, we cannot really tell. There could be an intermittent send problem on the cable itself, or perhaps Unity may be sending numerous, different MWI requests for many subscribers, and the PBX did not process all.
There are some traces that you can set to determine if the serial requests for out-bound MWI were successful, and TAC should be able to help out with setting, retrieving an analyzing those traces. Some people might want to jack up the MWI retry number, but if Unity is already sending too many MWI's too fast, that will make the issue worse.
Steve Olivier
Software Engineer
Cisco Systems
