Apparatus to interconnect two units that have telephone line connection ports are previously known. The present invention differs from known art in that its functions are completely automatic and that it does not need any other connections to computer or fax machine, than the telephone lines themselves. Known art usually requires either external connections to control logic or similar in order for the necessary connections / line switching to be established, or alternatively requires manual interventions by the user to initiate communications.

The present invention relates to devices to achieve previously known functions, such as the provision of line voltage, calling tones and ring signals etc., in an pre-programmed automatic way without the need for external control signals and without requiring manual invention.

A device according to the invention consists of a unit having a voltage source, preferably comprising one or more batteries, or a corresponding power supply adapter, an electronic circuit having the necessary components and circuits to obtain the mentioned automatic functions, and finally two standardised connectors for the telephone line wires. One for incoming line and one for outgoing lines..

The device is used in the following manner: The originating instrument, computer modem, telefax machine or corresponding instrument is connected to the connector for incoming line. The answering or receiving instrument, the computer modem, telefax machine or corresponding instrument is connected to the connector for outgoing line.

Transmission is initiated in for corresponding instrument normal ways, if the instruments require the transmission of a telephone number, any arbitrary number can be used.

No other action is required since the function is fully automatic.

The required tone signals, line voltage and ring signals are provided, so that the line towards originating instrument appears in the same way as if it had been connected to a telephone line and in a similar manner on the receiving side there is line voltage and ring signals, causing the receiving instrument to react exactly as if it would have been connected to a telephone line.

If receiving instrument is for instance a telefax machine, it will thus cause fully automatic reception of the document.

The following description is an example of an embodiment of the invention. The description is not to be seen as limiting the scope of the invention. The sole purpose of the description is to explain the principles of operation according to the present invention.

In the enclosed drawings, fig. 1 is a block diagram over the main parts necessary for the functions of the invention.

Fig. 2 is a circuit diagram showing an example of an apparatus according to the present invention. In the diagram the different parts corresponding to the numbers in the block diagram have been circled and correspondingly numbered.

In fig. 1 the connection for incoming telephone line is numbered 2 and the connection for outgoing line is numbered

1.

Connections 1 and 2 are interconnected via capacitor 7 allowing alternating current to pass, meaning that the normal modem signals are passing unobstructed from one connection to the other.

Line voltage is provided to the system by battery or battery

adapter 5. The switch 6 is activated by incoming line getting low impedance (line "off hook" activated). Supply voltage is thereby supplied to all functional units of the system. Simultaneously a first timer 3 is triggered by the application of supply voltage so that it generates an output signal during a pre-set time period. This output signal is connected to a second timer, 4, that in turn generates a tone signal corresponding to the dialling tone during the time controlled by timer 1. The tone signal is connected to the telephone line together with line voltage from the switch 6 so that the originating instrument sees the line as active. The logic unit 8, controlling ring signal generation is connected to timer 3 so that the generation of ring signals is inhibited during the first period when tone signals are transmitted. When the output signal from 3 ceases, the tone signal stops, and the logic unit 8 activates the generation of ring signals.

The ring signals are generated by applying the supply voltage to an oscillator whose output is connected to a so called voltage multiplier (diode cascade) according to known art. These two units are part of functional block 9 according to figure 1. The high voltage can alternatively be generated by a transformer, transforming the oscillator output before it is rectified.

The D.C. converter (voltage cascade) output plus and minus poles are connected to a switching device 10 consisting of complementary connected transistor stages arranged so that the output voltage mainly consists of a square wave with a voltage and frequency suitable for ring signals. The switching device 10, receives control signals from the logic unit 8, consisting of an appropriate driving frequency for the ring signal. This driving frequency is generated in intervals corresponding to normal ring signal interval timing.

The ring signal is connected to outgoing line 1. As soon as the instrument connected to this port is activated this can

be detected by the line impedance going low ("off hook"). This condition activates a second switch 11 that in addition to providing line voltage to outgoing line, also generates a signal to logic unit 8, inhibiting the generation of ring signals.

The switch 11 is activated by logic unit 8 during intervals between ring signal generation, so that line impedance can be detected in these intervals. Hereby the contact is automatically established and communication begins in the usual manner.

At deactivation of the units the line impedance ceases to be low, thereby deactivating the switch so that supply voltage is disconnected and the apparatus returns to its passive state, awaiting the next activation. In the passive state very little current is consumed making the incorporation of power switches superfluous in spite of the use of batteries.