This looks to be a form of "War Dialing" (coined from the movie "War Games").
We have received calls for multiple persons (names) from multiple collection company's at our number.
We have an unlisted/unpublished number and are on the national do not call registry.
As we do not have exact numbers (persons, company, etc) I could only do a rough estimate of the odds of receiving these calls. The ratio is similar to those found on a lottery ticket, I mean this literally.
This means there is an unseen factor in receiving the calls, leading to the theory of "War Dialing" an area code or prefix in search of "hits" for the person they are looking for.
Then consider if multiple collections companies were to coordinate their efforts (it would be to their advantage) of dialing and "hits".
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