Data communication circuit and method using telephone system

摘要

A pay phone capable of establishing data communications between a notebook computer and a remote communication device over a telephone line as well as voice communications between a telephone handset and a remote communication device over the same telephone line. The pay phone has a data communication circuit comprising a voice switching unit including a tip and ring switches which are connected to a central office line to receive voice data and a ring signal, respectively; a key input unit having a data communication key, a data communication change-over key and a numeric key pad; a voice communication unit having a handset for establishing voice communications when said tip and ring switches of the voice switching unit are switched-on; a tone detecting unit for detecting a calling tone in tone signals received from the central office line; a data switching unit having a tip and ring switches connected to the central office line for establishing data communications; and a control unit for controlling operations required for the voice communications and data communications in response to inputs of the calling tone, the data communication key signal and the data communication change-over signal.