> Filtering out any number that shares my area code and first three digits and not in my phone book would go a long way to getting rid of spam. Filtering by nu

> Filtering out any number that shares my area code and first three digits and not in my phone book would go a long way to getting rid of spam. Filtering by number is a lot easier when you have a number with a small state's area code when you have not lived there for some time. All unknown callers from that state are then easily identified as spam with 99% probability.