Caller ID (caller identification or CID, and more properly calling number identification - CNID) is a telephony intelligent network service that transmits the caller's telephone number and in some places the caller's name to the called party's telephone equipment during the ringing signal or when the call is being set up but before the call is answered. Typically, CNID is transmitted digitally using Bell 202 modulation between the first and second rings.
In 1982 Nélio Nicolai, a Brazilian inventor, created a machine capable of identifying and displaying the caller ID, he named it BINA (B identifies number of A).
The first market trial for caller ID and other "TouchStar" services was on July 7, 1984 in Orlando, Florida. Ellis D. Hill, the head of the BellSouth Product team, coined the term "caller ID." This market trial lasted seven months. It was conducted and analyzed by Bell Labs/AT&T Network Systems. In 1987, Bell Atlantic conducted another market trial in Hudson County, New Jersey, which was followed by limited deployment. BellSouth began the first commercial application of caller ID in December 1988 in Memphis, Tennessee and was the first regional Bell to fully deploy the system.
In 1995, Bellcore released another type of modulation similar to Bell 202 in which it became possible to transmit caller ID information and even provide call-disposition options while the user was already on the telephone. This service became known in some markets as call