My apologies if this idea has been posted by someone else and I missed it. I thought I'd share how I handle the junk calls on my Android phone without any apps or subscriptions to block them. While my method doesn't actually block them from calling me, it does keep them from interrupting my day or bothering me at all. It does take some time to set it up initially if you have a lot of contacts, but after that the only thing to remember is to give any new contacts their own ringtone so you won't miss a call from them. (You will still see any missed calls in the notification of recent/missed calls list though.) And that's basically what happens if you assign each of your contacts a personal ringtone. You can mix the ringtones. They don't have to have the same one, although that would work too. After that, the important thing to do is turn off the default ringtone in Sounds and Notifications and/or vibrate. From then on the only calls from people you know you will ring. Unwanted calls from numbers not in your contacts will stay silent. If, for some reason, you need to accept a call from someone who wouldn't normally be in your contacts but you left your number for them to call you back, then you can temporarily re-enable the default ringtone so you won't miss any incoming calls.
Android PIE makes this a very easy process. Just turn on Do Not Disturb and set it to ring for contacts only, set texts for contacts only too if you want. Then if you really want peace turn off visual disturbances. Now your phone sits black/dark and quiet UNLESS a contact calls you. Android OS does all the work and it takes under 2 minutes to set this up if desired. Its the ultimate spam call eliminator. Anyone can leave a message and if its a new friend you forgot to setup a contact for you take of it and call them back. You'll only miss their call once, but you will NEVER get a call from non-contacts bothering you.
