Abbreviation for Calling Line Identification. CLI is a service offered by telephone networks that discloses the calling party's telephone number. The service is offered under a variety of titles such as Caller-ID in the United States, and Calling Number Display in Australia and the UK. It allows CCA to identify the caller before answering, and to store the number and return missed calls. These features were not previously offered by telephone networks, which traditionally provided an anonymous service.