IP filtering is a method of anti-fraud protection used to blacklist a group of IP addresses that are known to be related to fraudulent activity. A company using an IP filter will take the IP addresses of incoming traffic and compare them against the blacklist of IP addresses usually consisting of known suspect data centers, Tor exit nodes, VPN’s, cloud services, and more.

Although it’s perfectly normal to see these IP addresses being used for routing traffic, it’s highly unlikely to be associated with a mobile device, and can be used as a strong indicator of fraud (or, perhaps more specifically, mobile fraud).