GB2323244A

GB2323244A - Method of switching

Info

Publication number: GB2323244A
Application number: GB9705301A
Authority: GB
Inventors: Andreas Muhlebach; Jeffrey Lai; Jia-Guo Han
Original assignee: Inventec Corp
Current assignee: Inventec Corp
Priority date: 1997-03-14
Filing date: 1997-03-14
Publication date: 1998-09-16
Also published as: GB9705301D0

Abstract

A method of switching a telephone call between branch telephones of a shared-line telephone system including the step of storing respective branch telephone code numbers in respective branch telephones through a respective key pad, the step of inputting the branch telephone code number of the designated branch telephone through the key pad of the picked up branch telephone, causing the designated branch telephone to be rung up.

Description

Title - METHOD OF SWITCHING The present invention relates to a method of switching a telephone call between branch telephones without using a telephone exchange. The invention relates also to telephone apparatus for the method.

Regular telephone exchange e systems are commonly heavy and expensive, and require much installation space.

Further, only experience4 engineers can install telephone exchange systems. Therefore, regular telephone exchange systems are commonly used in big offices and business places.

For small offices or families, it is not economic to install a telephone exchang e system. Without having a telephone exchange system, people may have to call one another personally or by voice when to switch a telephone call from one branch telephone to another. Ho-wever, calling people by voice makes noises.

The present invention has been accomplished to provide a telephone apparatus with the function of switching a telephone call between branch telephones which eliminates the aforesaid problems. According to the method and apparatus of the present invention, telephone users can store respective branch telephone code numbers in respective branch telephones through a respective key pad, so that a telephone call can be switched from one branch telephone to another by inputting the branch telephone code number of the designated branch telephone through the key pad of the picked up branch telephone. A telephone apparatus in accordance with the present invention comprises a DTMF signal receiver. When a first branch telephone receives a DTMF signal from a second branch telephone, the DTMF signal is decoded into a corresponding code signal by the DTMF signal receiver of the first branch telephone, and then compared by the CPU of the first branch telephone with the code number stored in the storage device thereof, so that the first branch telephone is rung up when the code number from the DTMF receiver is identified in conformity with the code number from the storage device.

The invention will now be described further by way of example with reference to the accompanying drawings in which: Fig. 1 is a circuit block diagram of a telephone apparatus according to the present invention; Fig. 2 is block diagram showing the switching of a phone call according to the present invention (the dotted line indicates the operation of the circuit of the telephone of the switching side; the real line indicates the operation of the circuit of the telephone of the side being switched; Fig. 3 is a control flow chart of the telephone apparatus according to the present invention; and Fig. 4 is a circuit diagram of a DTMF signal receiver according to the present invention.

Referring to Figure 1, the code numbers of branch telephones are set through a key pad 11 of a telephone 10, and stored in a storage device 13. When to switch a phone call to one branch telephone, the user of the telephone 10 can directly input the code number of the designated branch telephone through the key pad 11, thereby causing the designated branch telephone to send a corresponding DTMF signal to the other linked branch telephones. Upon receipt of the DTMF signal, the DTMF signal receiver 14 of each branch telephone immediately decodes the signal, and compares it with the value of the respective branch code number stored in the storage device thereof by the respective CPU.

When the DTMF signal is identified equal to the value of the branch code number of a particular branch telephone, such a particular branch telephone immediately gives a rhythmical sound informing its user of the incoming of a telephone call.

Referring to Figure 1 again, the telephone 10 comprises a key pad 11, a CPU 12, a storage device 13, a DTMF signal receiver 14, a DTMF signal generator 15, a telephone line 16, a tone generator 17, a tone amplifier 18, and a speaker 19. The other basic circuit structures, such as ringing circuit, dialing loop and display unit, etc., are of the known art and not within the scope of the present invention, therefore they are neither shown in Figure 1 nor described herein in detail.

Through the number keys and function keys of the key pad 11, the code numbers of all branch telephones are inputted into the telephone 10, and stored in the storage device 13 by the CPU 12.

The DTMF signal receiver 14 is connected to the telephone line 16.

When the telephone 10 receives a DTMF signal from one branch telephone through the telephone line 16, the dual-frequency DTMF signal which contains a high frequency signal and a low frequency signal is immediately decoded into a 4-digit digital signal by the DTMF signal receiver 14, and then the 4-digit digital signal is sent by the DTMF signal receiver 14 to the CPU 12 for comparison with the value of the code number stored in the storage device 13. If the comparison result is positive, the CPU 12 immediately gives a signal to the tone generator 17, causing it to produce a series tone signal. The tone signal from the tone generator 17 is then amplified by the tone amplifier 18, and then set out through the speaker 19, and therefore a series of sound is produced through the speaker 19, calling the user to pick up the handset of the telephone 10. If the comparison result is negative, the telephone does no work.

Referring to Figures 2 and 3, when one branch telephone users receives a telephone call for the user of another branch telephone from the exchange line, it can easily be switched to the branch telephone of the called part as follows: 1. When one particular branch telephone for example the first branch telephone receives a telephone call from the exchange line and rings a tone, the user of the first branch telephone finds that the telephone call is for calling the user of another branch telephone for example the second branch telephone, the user of the first branch telephone can then input the code number "#2" of the second branch telephone through the key pad of the first branch telephone.

2. When the CPU 12 of the first branch telephone receives the code number "#2" of the second branch telephone from the key pad 11 of the first branch telephone, it immediately controls the DTMF signal generator 15 of the first branch telephone produces a DTMF signal corresponding to the code number of the second branch telephone.

3. The DTMF signal from the DTMF signal generator of the first branch telephone is then transmitted through the telephone line 16 to the second branch telephone.

The second branch telephone is then operated as follows: 1. The DTMF signal from the first branch telephone through the telephone line 16 is decoded into a code number by the DTMF signal receiver 14 of the second branch telephone, and then sent to the CPU 12 of the second branch telephone. Figure 4 shows the circuit diagram of the DTMF signal receiver 14, in which contacts P11, P12, P13, P14, P15 and P16 are respectively connected to the CPU 12.

2. When the CPU 12 of the second branch telephone receives the code number from the DTMF signal receiver 14, the CPU 12 of the second branch telephone immediately compares the code number with the code number stored in the storage device 13 of the second branch telephone. If the received code number signal is confirmed in conformity with the code number stored in the storage device 13, the CPU 12 immediately drives the tone generator 17, causing it to produce a tone signal, and at the same time the internal counter of the CPU 12 is started to count.

If the received code number signal is rejected, the tone generator 17 of the second branch telephone does no work.

3. The tone signal from the tone generator 17 of the second branch telephone is then amplified by the tone amplifier 18 thereof, and then driven out of the respective speaker 19.

4. When the handset of the second branch telephone is picked up by the user, the telephone line 16 of the second branch telephone immediately produces a signal to the CPU 12 of the second branch telephone, causing it to stop the tone generator 18 of the second branch telephone and its internal counter.

5. If the handset of the second branch telephone is not picked up a predetermined length of time after the production of the tone through the speaker 19 of the second branch telephone, the CPU 12 of the second branch telephone immediately produces a stop signal to the tone generator 18 of the second branch telephone, causing it to stop the tone signal, and at the same time the internal counter of the CPU 12 of the second branch telephone is stopped.

It is to be understood that the drawings are designed for purposes of illustration only, and are not intended as a definition of the limits and scope of the invention disclosed.

Claims

1. A method of switching a telephone call between branch telephones, including the steps of: i) inputting respective code numbers of a set of linked branch telephones into respective branch telephones through- a respective key pad, permitting the inputted code numbers to be stored in a respective storage device by a respective CPU (central processing unit); ii) upon receipt of a DTMF signal by one branch telephone from another branch telephone through a telephone line, a DTMF signal receiver of the called branch telephone being driven to decode the DTMF signal into a decoded code number, and to send the decoded code number to the CPU thereof; iii) enabling the CPU of the called branch telephone to compare the decoded code number with the code number stored in the storage device thereof, and to drive a tone generator of the called branch telephone causing it to produce a series tone signal when the decoded code number is identified in conformity with the stored code number of the called branch telephone, or not to drive the tone generator when the decoded code number is not in conformity with the stored code number.

2. The method of claim 1 further comprising the step of permitting the tone signal from the tone generator to be amplified by a tone amplifier and then driven out of a speaker.

3. The method of claim 1 further comprising the step of driving the called branch telephone to produce a signal to its CPU when the called branch telephone is picked by the user to answer the call, causing the CPU to stop the tone generator from producing the tone signal.

4. The method of claim 1 further comprising the step of driving the CPU to stop the tone generator from producing the tone signal a predetermined length of time after the production of the tone signal.

5. A telephone apparatus for the method of claim 1, comprising: a CPU (central processing unit); a key pad connected to said CPU and having number keys and function keys for input of a code number; a storage device connected to said CPU and controlled by it to store the code number inputted through said key pad; a telephone line connected to said CPU and controlled by it to receive a telephone call from linked branch telephones or an exchange line; a DTMF signal receiver connected between said CPU and said telephone line, and adapted for decoding a DTMF signal received from one linked branch telephone through said telephone line into a digital signal and sending the decoded digital signal to said CPU; and a tone generator connected to said CPU and controlled by it to produce a series tone signal; wherein when the telephone receives a DTMF signal from one linked branch telephone, the DTMF signal is immediately sent to said DTMF signal receiver and decoded by it into a corresponding code number, permitting the decoded code number to be sent to said CPU for comparison with the code number stored in said storage device, so that said CPU drives said tone generator to produce a series tone signal when the code number from said DTMF signal receiver is identified in conformity with the code number from said storage device, or does not drive said tone generator when the code number from said DTMF signal receiver is not in conformity with the code number from said storage device.

6. The telephone apparatus of claim 5 further comprising a tone amplifier controlled by said CPU to amplify the tone signal from said tone generator, and a speaker controlled by said CPU to output the amplified tone signal from said tone amplifier.

7. The telephone apparatus of claim 5 further comprising a DTMF signal generator connected between said CPU and said telephone line, and controlled by a code number inputted from said key pad to produce a DTMF signal, permitting it to be transmitted through said telephone line to ring up one designated branch telephone.

8. A method of switching a telephone call between branch telephones substantially as herein described with reference to and as illustrated in the accompanying drawings.

9. A telephone apparatus substantially as herein described with reference to and as illustrated in the accompanying drawings.