Abstract: A call tracing and identification system for use with a public telephone network includes at least one interrogation and digital display circuit associated with a called-party telephone of the network, and an encoder circuit associated with a calling party telephone in the system. In response to an interrogation command initiated by a ringing signal or a line voltage change when the telephone is answered, the encoder circuit generates a series of coded signals and applies the same to the telephone for identifying the calling party by area code and telephone number. The identification signals are received by the display circuit of the called telephone where they are rapidly decoded, stored and displayed in digital form. The number of cycles of transmitted sine wave frequency is used for identification, and an output of a sequentially addressed memory to a display is gated in synchronism with the addressing at a rate sufficient to be visually imperceptible.