These numbers starting with 1 reminds me of an experiment a friend and I did in high school (50 years ago) in the San Francisco east bay area. This is before an initial 1 indicated 10 digits followed instead of 7, so the initial 3 digits were either an area code or prefix. We found all the 3 digit codes that were not one of these (as listed in the front of the phone book) and called them. We got test boards, test tones, and lots of different stuff.
Harold