A carrier endpoint defines a specific client on the carrier network. Typically the client IP address is used to identify the client, however on a carrier network this may be impractical when the client is using a mobile device. Other identifying information such as the MSIDSN number is used instead.

This information can be used to block a specific endpoint on the network. Reasons for blocking may include clients whose accounts have expired, clients from another carrier, clients who have sent malicious content (phishing, exploits, viruses, etc), or other violations of terms of use.