This app was mentioned in 5 comments, with an average of 4.60 upvotes
It's free to download but you have to have a paid subscription. Here's the link but it looks like recent reviewers are complaining about it.
It worked in front of my eyes. Maybe not all block calls are the same, who knows? But he explained to me that the app routes the call to an 800 type of number that the block rule doesn't apply to, then reroutes it back to you with the shown number.
Let me know how it works out. I like the idea but the cost is too expensive for me to justify spending $4/month on. I don't get many block calls. Come to think of it; I don't get many regular calls either. If I do get a block call I send them straight to voicemail with no remorse. Leave me a voicemail if you can't text. If I was being harassed that's a different thing. Probably would definitely pay it though.
https://play.google.com/store/apps/details?id=com.teltechcorp.trapcall
I have no idea if it will work or not, but you could try forwarding your landline to your cellphone & use this app or another one similar to it to unmask the phone #.
An article about TrapCall here.
Apparently, there is a free to try for a week app called Trapcall that can identify unknown numbers, though the reviews for it are pretty bad. Hopefully, it's just one of those annoying telemarketer robocalls.
Here's the link, for what it's worth: https://play.google.com/store/apps/details?id=com.teltechcorp.trapcall&hl=en_US
Plus you also have apps that unmask your phone number despite the *67. https://play.google.com/store/apps/details?id=com.teltechcorp.trapcall&hl=en
I'm having a hard time finding a single review that verifies the app does what it advertises: https://play.google.com/store/apps/details?id=com.teltechcorp.trapcall