Caller identification (Caller ID) is a telephone service. It is available in analog and digital telephone systems. That includes voice over IP (voIP).
The information received from the service is shown on a telephone display screen.
Type II caller ID[change | change source]
In early 1995, Bellcore released another type of modulation, similar to Bell 202. It became possible to send caller ID information while a user was already on the telephone. This service became call waiting ID.
Smartphones use third-party mobile apps to do name look ups.