Blocked numbers still coming through
I have blocked telemarketers numbers but they’re still coming through and I read if blocked numbers are still coming through. “There is a reason why for this, at least I heard Spammers, use a spoof app that hides their actual number from your caller i.d. so when they call you and you block the number, your blocking a number that doesn't exist.” Is this true or is there a way to truly block a call?
iPhone 6, iOS 12