Although caller ID service should never be used as a means of authentication for voice calls from outside the company, another method called automatic number identification (ANI) can. This service is provided when a company subscribes to toll-free services where the company pays for the incoming calls and is reliable for identification. Unlike caller ID, the telephone company switch does not use any information that is sent from a customer when providing the calling number. The number transmitted by ANI is the billing number assigned to the calling party.