When you dial a toll free number, the party you are calling pays for the call. Typically, the called party for toll free calls is able to identify your telephone number using a telephone network technology called Automatic Number Identification. FCC rules limit the subsequent use of this information and require carriers to inform consumers that telephone numbers are being transmitted in this way. Emergency Services Calls to emergency lines are exempted from Caller ID rules. State rules and policies govern carriers' obligation to honor caller privacy requests to emergency numbers.
Some services also transmit the name of the calling party.
The FCC's Caller ID rules require that, when a caller requests that the calling party number be concealed, a carrier may not reveal the name of the subscriber to that line.