ScopeIntended Audience: All End UsersThis document is intended to help customers to reduce their fraud attack from unlawful robocalls.Unlawful Robocalls (Within North America)In November 2017, the Federal Communication Commission (FCC) issued a report and order that described a number of specific types of robocalls considered to be unlawful. Further, in May 2019, the FCC released a declaratory ruling that gives service providers leeway to block unlawful robocalls at the network level by default, with the intent of preventing unlawful calls from reaching the general population in the first instance. The types of robocalls the FCC has specifically determined to be unlawful are calls made with:Invalid ANI/FROM telephone numbers (TNs)Unallocated ANI/FROM TNsBlank or alpha-numeric characters in ANI/FROM TNsTelephone numbers on the Do Not Originate (DNO) List(s)Here are the best practices that customers can follow to prevent the flow of unlawful robocalls from their network toward ours:Make sure all of your voice calling traffic contains good/valid telephone numbers in the ANI/FROM fields. See the definitions of the various types of ANI/FROM fields below. Ensure that all of your calls toward our network meet the following “VALID” criteria.VALID: A valid NPA-NXX-XXXX in the NANPUNALLOCATED: A valid NPA NXX XXXX in the NANP, but NOT assigned either to a carrier or in the LERGINVALID NUMBER: A complete telephone number (TN) that is NOT VALID, but of the correct format [2-9][0-9][0-9] [2-9][0-9][0-9] [0-9][0-9][0-9][0-9] (i.e. 10 digits in length, 1st and 4th are [2-9] all others are [0-9])INVALID DIGITS: The calling party number is numeric, but doesn’t fit into a category defined above (all 1's, partial entry <10 digits, etc.)8YY: The calling party number is an 8YY number911: The calling party number is 911411: The calling party number is 411N11: The calling party number is any of N11 number besides 911 or 411555: The NXX is 555ALPHA: The calling party number has 'alpha' characters that are random or the word ANONYMOUS in itEMPTY: There’s no calling party number presentMake sure that calls from your network or from your customer never have ANI/FROM phone numbers that fall into the UNALLOCATED, INVALID, N11, Alpha or Empty ANI categories. Please be aware that if any of these types of calls leave your network and are sent toward us, you run the risk of these calls being BLOCKED by us or another downstream service provider.Review your customer use cases and discourage short-duration (<15 seconds) calling. Short-duration calls raise flags on most service provider networks and may lead to Call Blocking per the FCC guidelines.