For phone calls, somewhere between 30 and 50 percent of my calls are robocalls or other telemarketing (I receive far more emails than phone calls).
If there were an easy way to tell my phone to just drop callers if they aren't in my phone book, I would. Right now, my phone lets me know if a caller is a suspected spammer, but when I hit dismiss, it goes to voicemail. I'd rather have the call just dropped or for the caller to get a busy signal. That reminds me - I can't remember the last time I heard a busy signal.