I realize this doesn't do much for your cell number already in the wild but if you want to migrate people over to a number that screens before routing to you, it's possible to do on the cheap.
I ported my landline number to Callcentric partially just to rid myself of the AT & T $75/mo charge and partially because of Callcentric's call handling.
Callcentric (and I'm sure others) allow call routing rules which include inputs for spam ranking, whitelist and IVR routing. You can upload your contacts, whitelist those for passthrough and then send anyone else to a simple "please press <fixed digit|random digit> " prompt first before routing to you if they pass the test.
I ported my landline number to Callcentric partially just to rid myself of the AT & T $75/mo charge and partially because of Callcentric's call handling.
Callcentric (and I'm sure others) allow call routing rules which include inputs for spam ranking, whitelist and IVR routing. You can upload your contacts, whitelist those for passthrough and then send anyone else to a simple "please press <fixed digit|random digit> " prompt first before routing to you if they pass the test.
https://www.thetelecomspot.com/grandstream-ht801.html
If you prefer to own the hardware yourself, it's possible to do the same by loading asterisk on a raspberry pi.
https://brezular.com/2019/01/02/asterisk-on-raspberry-pi/