As i said mate, dont know another way to put it.
If clients knew if all comms where gone for what ever reason, that no one would know about it for hours - im sure they wouldnt be to happy, especially with todays technology.
I understand to poll every system, every few seconds, (1000's) of them, is a big undertaking, but 5 hrs or more is taking the you know what.
I'll admit, i never knew until this thread.