Abstract: The dual equipment for identification of telephone calls is a terminal electronic device that meets the telephone specifications for the service of Caller Identification. It is an intelligent electronic equipment that is connected to the telephone line of a called user that, upon receiving a call phone, presents through a liquid crystal display the caller's telephone number information. The equipment can also store in the memory the telephone call identification when the subscriber is not in his place of business, and thus when the user returns he can check who called, or from which telephone number, as well as the date and time. It consists of a battery eliminator entry for its power supply and a support battery, it identifies the information sent to it by the network through the input signalization that can be of DMF (Dual Tone Multifrequency) type or FSK (Frequency Shift Keying) type.