Nomorobo actively maintains a very large database of active robocallers, but robocallers create new numbers all the time.
The Nomorobo detection system often detects these numbers just a few minutes after they become active, however by this point it is possible they have already called several thousand numbers, so it sounds like your number happens to be one of the early unfortunate few.
To assist in early detection, we would very much appreciate reporting any new numbers. We review every single one of these reports, and regularly add the reported numbers to our global database.
To report numbers calling your landline, login to your Nomorobo.com account and click the "Report a Number" link located on the right side of the page.
To report numbers using the iPhone app, click on the Report icon located at the bottom of the iOS app. Add the number, and then select Allowed or Blocked depending on whether you think the number should be allowed through or flagged as a robocaller.