Trunk to trunk SIP 3 minute cutoff timer. Cannot for my life where this is happening. Any pointers?

LOL, weird. So I assign a timer COS just for giggles and the problem goes away.

What class did you change it to and what changes if any to the class of service you are using?

Just the PRI to 1 and the SIP lines to 2 Just adjusted timers like there were on the default. I have a sneaking suspicion that when I did this upgrade years ago from a UX that somehow that timer MB is not right.

I think those timers are set in either VRS/DISA or Transfer.