CPNI stands for Customer Proprietary Network Information. This information can include the telephone numbers you call, when you call them, and the services that you subscribe to. This information is collected by your telephone company to provide these services and detailed billing to you. The release of this information is protected by laws imposed by Congress and the FCC. These laws require all telephone service providers (including cellular and VoIP service) to ask for identification or a password to release this information to anyone.