now, THAT *IS* unusual. (both things.)
Usually false positives like that stem from either an old contact with that number (Delinquent Dan hooks up with sleezy suzie, and they use her phone number and address to get some service or whatever. They of course, default, and now suzie is listed as a point of contact for Dan. Now, they let the number lapse, or get a new number, or [insert mechanism for number becoming available here], yet the credit reporting agencies dont record that this has happened. Suzie's old number now belongs to Innocent Ian, who has never been involved with Suzie, or Dan. He just has their old number. Collections agency will call Ian, demand to speak with Suzie or Dan. Ian, naturally-- says neither live there. In fact, he has no idea who they are. The collections agency does not buy it-- Dan and Susie lie to collectors all the damn time, and "they arent here" is a fan favorite. Before they will expunge that datapoint, they need to corroborate that the number has indeed changed. The requirements for that process vary from agency to agency, but are usually a multi-point requirement based system of some sort. (Several bits of evidence need to converge to prove that you are indeed who you say you are, and that you are not their lieing cousin larry, covering for them once again.) Should you succeed in getting the datapoint for the phone number expunged, it has to percolate through all the many layers of the debt collection industry, before other agencies get the hint. (Dan likely has many debts being sought through many agencies.)
It COULD be that yours is a condition where your number is being flagged by one system, using a datapoint that has been expunged in another system. (say--- let's assume that the debt is to a phone company-- the very one that issued the phone number. That phone company KNOWS that Dan no longer has that number. They know that, because they issued it to somebody else-- in this case, Ian. They inform one agency that the contact number for Dan is no longer valid for that debt, and that they need to correlate a new one based on more recent debt records. That agency expunges the records, but the credit report still has the old number as the point of contact. The cold-call list gets generated based on the credit report, which still has the obsolete data-- So an agent calls Ian--- Ian tells the agent "Not me, please double check your records." The agent double checks-- indeed, that number is no longer associated with Dan (as the original credit extender has informed the agency, and the record was expunged for that number)-- however, humans running the cold calling system did not properly integrate the two systems, so it keeps spitting out that number.
Automated clusterfucks like that are one of the many reasons the (now closed-- the owners got too old to continue, and closed up the business) agency I interned at still relied on manually and meticulously maintained paper records. No robots giving nonsense instructions to agents to call people, since the numbers in the file were immediately reflective of the current situation after manual revision. The operators of that agency would create the next day's call list based on the data available after the prior day's operations came to a close.
(others being data integrity against loss from viruses, malicious software, and botched database management. They were frequently utilized as "hard copy" backup services by several other agencies that were frequently plagued by such issues.)