Electronic surveillance interface

In April 1996, the FBI issued the Electronic Surveillance Interface (ESI), a document that describes the delivery format it wanted carriers to use in delivering intercepted communications to law enforcement. In addition, the document described the types of information, such as location information and service status messages, that law enforcement would like to receive as part of an interception. The ESI was useful as an expression of law enforcement desires and as a contribution to the CALEA standards process.