I do the same, but my contact is labeled $PAM (Spam) with a photo of Spam and assigned no ringtone. On Android, I can also mark the entire contact as "Auto Reject".
Same thing, someone with a very thick southern accent called and asked for "Dwayne" even though it came from an LA area code, told them they had wrong number, proceeded to try to ask me to help veterans, had to interrupt and explain I was at work and expecting a different call
I do the same, but my contact is labeled $PAM (Spam) with a photo of Spam and assigned no ringtone. On Android, I can also mark the entire contact as "Auto Reject".