Short for automatic number identification, a service that provides the telephone number of an incoming call. ANI is used for a variety of functions -- by receiving the incoming telephone number, telephone companies can direct a call to the proper long distance carrier's equipment; it can help identify the caller's address to speed response time to 911 calls; and it can route an 800 call to the nearest vendor. ISDN, the standards for transmissions on telephone lines, supports ANI.
