Lawful interception

Lawful interception is the electronic surveillance of telecommunication services, such as telephone calls or e-mail messages, as approved by law. It is usually done by law enforcement and intelligence agencies. In some places, the law allows such agencies to monitor otherwise private communications data under certain circumstances. This is done for analysis or evidence. It has become an important tool for law enforcement.
The data gathered is generally signalling or network management information. In fewer cases, it may also be the content of the communications (for example, the conversation or written message).