I've noticed a huge uptick in robo-calls using the same area code as my phone number. I no longer live in that area of the country, so I know that calls from this area code (that aren't in my contact list) are spam.
I've tried a few of the most popular call blocking apps, but have failed to find any that both let me block by area code and also let me whitelist the numbers in my contact list (so the people I know aren't blocked).
A user has asked a similar question here, but given the comment discussion below the answer, it seems that it no longer works.
