I struggle to imagine what non-segregated resource would be so central as to affect their customer-facing app platform, internal email (or maybe mail gateways), and call center.

Maybe DNS got hosed? I mean pretty impressive ransomware if it swept across the company that far and wide, crossing so many network boundaries and resource types so quickly.

Maybe accounts/control being held for ransom instead of storage encryption (what I usually think of as ransomware).