ANI (Automatic Number Identification) is a service that provides the receiver of a telephone call with the number of the calling phone. The method of providing this information is determined by the service provider (such as AT&T, MCI, Sprint, and so forth). The service is often provided by sending the digital tone multi frequency (DTMF) tones along with the call. Home users of ANI can screen callers.
ANI is commonly used by emergency center dispatchers to save the caller having to report the information and, when necessary, to help locate callers. A telephone company's 9-1-1 service to a public safety point usually includes the ANI feature.
In a call center, ANI displays the number of the calling party to the call center agent in real time. Among other things, the call center can use the information to forward calls to different people for different geographic areas.
ANI was originally developed by AT&T for internal long-distance billing purposes. ANI is not related to newer "Caller ID" services, though it serves a similar function, as it utilizes different underlying technologies.
ANI data is generally transmitted in-band using multi-frequency (MF) signaling, though ISDN PRI users can transmit separately.
The term "ANI" is used exclusively in North America and is part of the Inward WATS Service (Wide Area Telephone Service)