There is also a hard copy book that businesses buy, we called it a "Criss-Cross".
Listings for businesses, also had employee's names. Then using either the employer / employee name, get the phone number and/or address. All sorts of way to "cross" reference folks and where they worked.
Legitimate use - yes I used ours for legitimate reasons. Say a lady left her glasses, I could look her up and find out where she worked and for how long. Call her office and let her know where her glasses were left.
Crooks "secured" these too.
I got a call one night my alarm had gone off...I went to check on alarm. I kept driving because there was NO alarm going off, some lights were out and I thought I saw a car in the shadows...I went straight to the police station and had quite a few LEO's check this out....then give me the okay to drive on up.
Another fellow had the same type call - except he was grabbed outside his front door at gunpoint - his assistants kept his family hostage.
I immediatly changed Security measures. I always called the Alarm Company back for password exchanges and to make sure the LEO was called.
Even tho I had an unlisted number at the time - records showed someone called a LEO dept - reported hitting my car door in a parking lot and wanting to know how to reach me thru my license plate. They ran my plates and told them. Seemed innocent and "honest". I didn't get mad either...
There is a reason I did not have my apt rented in my name, I have been known to have my utilities listed in another person's name. That is another trick a BG used to find out stuff about me. Called the Utility company and said he was the Owner ( of of town partner of owners) and needed to know how to contact me and "which car" was mine.
I had two vehicles...and I was being cased, followed and an attempt to run me off the road occurred. The "Pro's" at the time like to do that - catch you out - kidnap and make you get them the valuables.
Hence the low profile, think outside the box, think like a crook, and hide in plain site comments I make.