Hi.
I'm experiencing a similar problem.
Last night we have migrated from 4.x CM to a new 8.6.2 CUCM, tested before in a testing environment.
This morning happen that sometimes, all external calls are resetted.
I can't address where is the problem.
Old configuration used router as h323 gateways, maybe could this configuration be the problem?
Thanks a lor for any suggestions.
Daniele