How can a toll free number be disconnected..... that doesn’t make sense ?! Can you not normally call those numbers back

The caller ID that’s pushed to you on an inbound call isn’t necessarily the number that’s dialing you. The ANI is the actual number dialing you, but it can be overridden easily with an override label sent to the carrier by the caller.

It's a number just like other number. It can be shut down anytime.

Scammers use defunct numbers when they spoof.

They are spoofed numbers