Where is the phone blacklist stored?

I have a problem with spam calls, they call me many times a day. To solve this problem, I've tried many call blockers apps (NoPhoneSpam, Calls Blacklist, CallBlocker, etc...) and none of them work. Some of them worked for a while, but then stopped to work. The spammers use a prefix and change the last 3 or 4 numbers of the phone, and I want to block them all. The android native phone app allows me to block numbers, and it works, but without wildcards, so I can't block all numbers with a given prefix without entering them one by one (not an option). I want to know if the Phone app blacklist is stored anywhere that I can edit it with a text editor, or if there is a way to add phones to it using terminal, so I can write a script to add all phones I want to block.