I'm not sure what it writes in the TCD when this happens. You will certainly see it write a message in the Call Router window, if you have typical rttrace settings for debugging.
Yes, the registry controls the upper bound on this value. But you may be able to set the MRD value slightly under this (I have done so with the Email channel) then you may get a Call Disposition in the TCD of:
41 = Maximum Task Lifetime Exceeded. The ICM software did not receive an End Task message for this task within the maximum task lifetime of the MRD with which the task is associated.
I can't recall if you can change the timeout on the voice channel as an MRD.
I have not investigated this. I think you should make a test call and see what it says in the Termiination_Call_Detail table.
Regards,
Geoff