In my world we have incidences of hi insight showing people knew better but ignored, and why in the hell didn't you check all the time.
IE, Trauma Center One has all there Primary Phone Lines through big telecom.
So, in an effort to have a backup Trauma Center One goes with little Telecom One.
But, Big Telecom One owns all the connections going into the Hospital Anyways.
And, Trauma Center One never told Little Telecom One that they where to be a backup or that there was any one else in the mix.
We see this all the time.
Where the backup company still uses the primary company at some point and when the primary crashes everything goes down anyways.