Similar, I used to work for a guard company. We implemented a process where employees reported to work by calling from an assigned set of phones at each client. they also signed out of work by calling from the same number.

needless to say we had all sorts of attempts to use other numbers but that never would work. since we had ANI numbers I doubt they could be spoofed.

now we never went as far as having them call in hourly, likely that would be dependent on client requirements. still I understand why the guy in the article was fired and honestly if he was skipping out then so be it