Abstract: A telephone system and a method and medium for operating a telephone system in a multi-function product equipped with an analog telephone circuit to realize a telephone function such that analog voice signals can be sent/received at a low price are provided. A method of operating a telephone system in a multi-function product, may include determining whether a receiver is in an off-hook state or on-hook state when a ring signal is sensed; determining whether a multi-function product is in a telephone mode or a fax mode according to whether the receiver is in the off-hook state or on-hook state; and analog processing a voice alternating current signal input from the public telephone network in a telephone circuit to output to the receiver, or digital processing a fax signal input from the public telephone network to print or store the fax signal, according to a determined mode of the multi-function product.

Abstract: The communication terminal device includes a handset, a central controller, a telephone network adaptor unit for converting analog signals transmitted/received between telecommunication network and the communication terminal device into digital signals, an interface unit physically isolating the central controller from the telephone network adaptor unit, and transmitting/receiving the converted digital signals between the central controller and the telephone network adaptor unit, and a telephone circuit unit which transmits the voice signals generated by processing the digital signals received from the telephone network adaptor unit to a handset through the interface unit and transmits the digital signals generated by processing the voice signals received from the handset to the telephone network adaptor unit through the interface unit.

Abstract: A main terminal and a method of operating the same. In this method of operating the main terminal, the main terminal is connected to a telephone network so as to communicate with the telephone network, and selectively connects an external terminal to the telephone network. To perform the method, first, if it is requested that the telephone network be disconnected from the external terminal and instead be connected to the main terminal, an internal current to flow into the main terminal is obtained from a loop voltage generated when the external terminal is in connection with the telephone network. Next, the internal current is applied to the main terminal. Thereafter, the telephone network is disconnected from the external terminal and instead connected to the main terminal. While the internal current is flowing in the main terminal, the main terminal maintains the loop voltage generated when the external terminal is in connection with the telephone network.

Abstract: A telecommunication terminal device includes a network connection unit having at least a first pin and a second pin to which a public telephone network is connected, and a third pin and a fourth pin through which a first external terminal device of a first type is connected to the first and the second pins; a first switching unit for selectively connecting the public telephone network with the first external terminal device and a second external terminal device of a second type; a first external terminal connection unit having a fifth pin and a sixth pin through which the second external terminal device is connected to the first and the second pins; and a feeding circuit connected to the first and the second pins to keep flow of currents provided from the public telephone network. The telecommunication terminal device is capable of exchanging telecommunication signals regardless of serial or parallel connection to additional external terminal devices.

Abstract: A telecommunication facsimile set accommodating transmission and reception of facsimile data during a telephone conversation on a telephone handset built into a facsimile machine, and placement of an established connection between the telephone handset built into the facsimile telecommunication set to put the connection on hold in order to talk with another caller via a second telephone line. The facsimile telecommunications set may be constructed with a microprocessor controller sensing both telephone signals and user activated signals, and sending control signals which activate circuit switching relays causing either the facsimile telephone handset or the facsimile modem to connect to either of the two telephone lines.

Abstract: A DTMF transmission method for a facsimile system which comprises an operating panel for generating key data according to operation of numeric keys, a dialing section of a telephone for receiving numeric key data from the operating panel and thus generating a DTMF signal, and a modem for detecting the DTMF signal received from the dialing section. The method comprises the steps of detecting the DTMF signal with the modem while power is supplied to the facsimile system and the telephone is in its hook-off state, displaying a telephone number corresponding to the detected DTMF signal, and storing the telephone number corresponding to the detected DTMF signal.