CLI Caller Line Identification, CLI, is a facility that enables identification of a user who requests access to a network via an ISDN line. The principle behind CLI is basically the same as is used for caller identification on many newer telephones. On an ISDN line the caller’s telephone number is transmitted as part of the call processing information on the D channel. If the network’s server recognises the number as being ‘safe’, the user is granted access. CLI is thus a fairly unsophisticated but also a very quick way to regulate network access for outside users.
