WO2001050784A1

WO2001050784A1 - Telephone call device and method thereof

Info

Publication number: WO2001050784A1
Application number: PCT/KR2000/000311
Authority: WO
Inventors: Seung-Mok Kang
Original assignee: Hansung Teliann Inc.
Priority date: 2000-01-04
Filing date: 2000-04-06
Publication date: 2001-07-12
Also published as: KR20010069174A

Abstract

A telephone call device and a method thereof can lower a telephone call rate, even though a caller and a receiver use any kind of terminal. When a phone call is made from an extension to a central office line, a conventional method is employed. In case the phone call is made from the extension to a portable terminal or vice versa, the phone call is performed through a special exchange for a wireless communication network, without passing a conventional local telephone network. As a result, the telephone call rate is lowered, and the wireless communication companies also save the cost, thereby increasing the subscribers.

Description

TELEPHONE CALL DEVICE AND METHOD THEREOF

TECHNICAL FIELD

The present invention relates to a telephone call device and a method thereof, and in particular to an improved telephone call device that can lower a telephone call rate, when a phone call is made between a caller and a receiver, and a method thereof.

BACKGROUND ART Recently, a number of the users of portable terminals, such as personal communication systems and cellular phones has been sharply increased. As a result, a number of the users that make a phone call from general wire telephones to the portable terminals or vise versa has been also increased. When making a phone call from one wire telephone to another wire telephone or from one portable terminal to another portable terminal, the user can take a predetermined discount in a midnight discount time, and need not to pay a telephone call rate to a communication company. However, in case the user makes a phone call from the portable terminal to the wire telephone or vice versa, there is no discount. Accordingly, wire telephone subscribers must defray high telephone charges.

DISCLOSURE OF THE INVENTION Therefore, it is an object of the present invention to provide a telephone call device that can reduce telephone charges, even though a caller and a receiver employ any kind of telephone terminal, and a method thereof. In order to achieve the above-described object of the present invention, there is provided a telephone call device including: a call signal processing unit for processing call signals between internal subscribers and external subscribers who subscribe to a public switched telephone network (PSTN) ; a switching control unit having a built-in exchange for a wireless communication network, for switch-controlling central office line channels and wireless channels according to transmitted and received telephone number types so that a telephone call can be performed between the internal and external subscribers through the exchange for the wireless communication network without passing a local telephone network; and a control unit for controlling the operation of the call signal processing unit and the switching control unit.

In addition, there is provided a telephone call method wherein internal subscribers make a phone call to external subscribers through an exchange for a wireless communication network, without passing a local telephone network, according to transmitted telephone number types, and the internal subscribers receive a phone call from the external subscribers through the exchange for the wireless communication network, without passing the local telephone network, according to received telephone number types.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a block diagram illustrating a telephone call device in accordance with a preferred embodiment of the present invention;

Figure 2 is an internal structure diagram illustrating a switching control unit as shown in Figure 1;

Figures 3a to 3d are flowcharts showing a call-making operation in the telephone call device in accordance with the present invention; and

Figures 4a and 4b are flowcharts showing a call-receiving operation in the telephone call device in accordance with the present invention.

MODES FOR CARRYING OUT THE PREFERRED EMBODIMENTS A telephone call device and a method thereof in accordance with a preferred embodiment of the present invention will now be described in more detail with reference to the accompanying drawings.

Figure 1 is a block diagram illustrating the telephone call device in accordance with the preferred embodiment of the present invention.

The telephone call device is disposed between a private branch exchange (PBX) 10 and a public switched telephone network (PSTN) 20.

In addition, the telephone call device may be provided between the private branch exchange 10 and a general telephone and between the private branch exchange 10 and a cellular phone and trunk radio system (TRS) network. Furthermore, the telephone call device according to the present invention can be applied to various telephone networks, such as a local telephone network, a trunk telephone network in a local area, a long distance telephone network, an international telephone network and a wireless telephone network.

The private branch exchange 10 is an exchange device which is installed in a company or building, and which serves to connect internal subscribers to external subscribers who subscribe to the public switched telephone network 20. In general, the private branch exchange 10 connects the internal subscribers, the internal subscribers to the external subscribers and vice versa, by employing m+n internal subscriber lines (channels).

When a general wire telephone user of the internal subscriber line picks up the receiver, subscriber line interface circuit units 30a~30 (m+n) check an ON/OFF condition of a hook switch and transmit a check result signal to a control unit 100. In the case that the general wire telephone user picks up the receiver, a current operational voltage (for example, 48V) is lowered to a predetermined one (for example, 5V) in order to smoothly process the signal in codecs 40aY0(m+n) . In case a call is received, a ring signal is transmitted to the telephone set.

The codecs 40a~40 (m+n) are connected between the subscriber line interface circuit units 30a~30 (m+n) and echo cancellers 50a~50 (m+n) , respectively. When the internal subscriber makes the phone call, the codec 40a~40(m+n) converts an analog signal from the subscriber line interface circuit unit 30a~30 (m+n) into a corresponding digital signal, and transmits the resultant signal into the echo canceller 50a~50 (m+n) . In case the internal subscriber answers the phone, the codec 40a~40(m+n) converts a digital signal inputted from the echo canceller 50a~50 (m+n) into a corresponding analog signal, and transmits the resultant signal to the corresponding subscriber line interface circuit unit 30a~30 (m+n) . The echo cancellers 50a~50 (m+n) are connected between the codecs 40a~40(m+n) and codecs 60a~60 (m+n) , respectively.

When the internal subscriber makes the phone call, the echo canceller 50a~50 (m+n) cancels an echo element in the digital signal from the codec 60a~60 (m+n) , and transmits the digital signal to the codec 60a~60 (m+n) .

In the case that the internal subscriber answers the phone, the echo canceller 50a~50 (m+n) cancels the echo element in the digital signal from the codec 60a~60(m+n), and transmits the digital signal to the codec 40a~40(m+n). In general, the echo canceller 50a~50 (m+n) generates a replication signal of the echo signal from the transmitted signal, and transmits the replication signal after a reciprocating transmission time of a corresponding transmission path, thereby canceling the echo signal. For this, as soon as the subscriber line interface circuit units 30a~30 (m+n) are off or the ring signal is inputted from data access alignment (DAA) units 80a~80m and portable terminals HP, the echo cancellers 50a~50 (m+n) must be operated for learning. When and after the phone is disconnected, the operation of the echo cancellers 50a~50 (m+n) stops. The codecs 60a~60 (m+n) are connected between the echo cancellers 50a~50 (m+n) and a switching controller 70.

When the internal subscriber makes the phone call, the codec 60a~60 (m+n) converts the digital signal wherein the echo is cancelled and which is inputted through the echo canceller 50a~50 (m+n) into the corresponding analog signal, and transmits the resultant signal into the switching control unit 70.

In case the internal subscriber answers the phone, the codec 60a~60 (m+n) converts the analog signal inputted from the switching control unit 70 into the corresponding digital signal, and transmits the resultant signal to the corresponding echo canceller 50a~50 (m+n) .

The switching control unit 70 includes a built-in exchanger for a wireless communication network, which can perform a switching operation without passing a general local telephone network. The switching control unit 70 is installed between the codecs 60a~60 (m+n) and the public switched telephone network 20 and between the codecs 60a~60 (m+n) and the cellular phone and TRS network. In addition, the switching control unit 70 exchanges the extension and the central office lines, and the extension and the cellular phone and TRS network.

When a phone call is made to the portable terminal through the extension (m+n internal subscriber lines) , it passes the exchange for the wireless communication network. As a result, it is like the phone call is made from one portable terminal to another portable terminal.

Conversely, when a phone call is received from the portable terminal, it must also pass the exchange for the wireless communication network. Accordingly, it is like the phone call is received by employing the portable terminal. The control unit 100 controls the operation and channels CHl-CHn of the subscriber line interface circuit units 30a~30 (m+n) , the echo cancellers 50a~50 (m+n) , the switching control unit 70 and the data access alignment units 80a~80m, by using a dial tone value detected from a DTMF block 110. The control unit 100 transmits the dial tone detected from the DTMF block 110 to central office lines l~m.

The control unit 100 transmits a telephone number detected from the DTMF block 110 to the portable terminal, thereby enabling the portable terminal to automatically make a phone call. In addition, the control unit 100 enables the portable terminal to disconnect a call. When an error is generated in the portable terminal, the control unit 100 turns off the portable terminal and then turn it on.

The control unit 100 controls the switching control unit 70 after comparing the telephone numbers detected by hooking off the switch in the subscriber line interface circuit units 30a~30 (m+n) , thereby transmitting the telephone numbers to empty channels required for the portable terminals or central office lines. Also, the control unit 100 controls the switching control unit 70, in order to connect the channel connected to the central office line or portable terminal to the empty extension.

The data access alignment units 80a~80m connect the switching control unit 70 to the central office lines l~m of the public switched telephone network 20. Reference numerals 90a~90n denote the channels CHYCHn for connecting the switching control unit 70 to the cellular phone and TRS networks HP&TRSl-HP&TRSn.

On the other hand, according to the preferred embodiment of the present invention, the subscriber line interface circuit units 30a~30 (m+n) , the codecs 40a~40 (m+n) , 60a~60 (m+n) , the echo cancellers 50a~50 (m+n) and the data access alignment units 80a~80m are generally called a call signal processing unit. The call signal processing unit transmits a call signal from the internal subscriber to the external subscriber, and a call signal from the external subscriber to the internal subscriber. The call signal processing unit, the switching control unit 70, the control unit 100 and the DTMF block 110 are integrated on a single board. The board is installed at a region of an internal terminal box where telephone lines are concentrated.

Figure 2 is an internal structure diagram illustrating the switching control unit as shown in Figure 1.

The switching control unit 70 includes m+n exchanges for the wireless communication network 72a~72m, 74a~74n that are respectively disposed between the internal subscriber lines (m+n channels) and the channels of the central office lines and the cellular phone and TRS network, which correspond to the internal subscriber lines.

Each of the exchanges for the wireless communication network 72a~72m, 74a~74n includes exchange units A, B for transmitting and receiving signals for each channel. The exchange units A, B of the exchanges for the wireless communication network 72a~72m, 74a~74n can transmit and receive the signals each other in the corresponding channel, and can transmit and receive the signals to and from the exchange units in another exchange for the wireless communication network. For example, when the exchange unit A of the exchange for the wireless communication network 72a intends to transmit the signal to the exchange unit B thereof, if the exchange unit B can be connected, the exchange unit A is connected to the exchange unit B. However, in case the exchange unit B of the exchange for the wireless communication network 72a cannot be connected, the exchange unit A judges connection possibility of the exchange B of another exchange for the wireless communication network 72a+l~74m, and then is connected to the exchange unit B that can be connected. The operation of the telephone call device in accordance with the preferred embodiment of the present invention will now be described.

Firstly, the call-making operation of the internal subscriber to the central office line or portable terminal will now be explained with reference to Figures 3a to 3d.

Before making the phone call, the control unit 100 checks a telephone wait condition by employing the subscriber line interface circuit units 30a~30 (m+n) . For instance, when a switch of one subscriber line interface circuit unit 30a~30 (m+n) is hooked off (SI), the echo canceller provided correspondingly to the subscriber line interface circuit unit is operated (S2) .

Thereafter, the control unit 100 judges whether an empty channel exists in the public switched telephone network 20. In case there is the empty channel ("Yes" in S3), the control unit 100 controls the switching control unit 70, thereby connecting the line of the private branch exchange 10 to the empty channel (S4) and the data access alignment unit 80a~80m (S5) . The control unit 100 detects a DTMF signal, and transmits it to the portable terminal or central office line. During the transmission, if the user hangs up in the subscriber line interface unit 30a~30 (m+n) that is hooked off, the corresponding central office line is disconnected (Sβ-SlO).

In step 3 (S3) , in case an empty external subscriber line does not exist in the public switched telephone network 20, it moves to step 11 (Sll) . While the telephone number is detected, a dial tone having a predetermined frequency level (for example, about 400Hz) is transmitted.

Thereafter, the control unit 100 detects the telephone number (S12), and transmits it to the portable terminal or the general wire telephone connected to the central office line.

When the detected telephone number is a call to the central office line ("No" in S13), the control unit 100 transmits a busy tone (for example, an intermittent sound of 600Hz generated at intervals of 0.5 to 3 seconds) to the internal subscriber (S14) . When the subscriber line interface circuit unit 30a~30 (m+n) and a predetermined number of data access alignment units 80a~80m that are connected to the central office line are on ("No" in S15) , the control unit 100 judges whether the external subscriber lines connected to the public switched telephone network 20 are full (Slβ) .

In step 16 (Slβ), in case the external subscriber lines connected to the public switched telephone network 20 are not full

("No" in Slβ) , the control unit 100 controls the switching control unit 70, thereby connecting the internal subscriber line of the private branch exchange 10 to the empty central office line of the public switched telephone network 20 (S17 ) . Then, the control unit 100 turns off a hook switch of the central office exchange between the empty central office line and the switching control unit 70 (S18), and transmits the telephone number (DTMF) (S19) . When the switch is hooked on in the subscriber line interface circuit unit, the corresponding central office line is disconnected.

On the other hand, when the telephone number detected in step 12 (S12) is a call to the portable terminal, it moves to step 20 (S20) . The control unit 100 checks whether the portable terminal channels 90a~90n are full. If they are not, the control unit 100 judges whether the portable terminal channel has an error (S21) . If the portable terminal channel does not have the error, the channel of the private branch exchange 10 is connected to the portable terminal channel (S22). In step 12 (S12) , in case the internal subscriber hangs up (SLIC is hooked on) , it goes to step 23 (S23) , and thus the dial tone is off. In step 15 (S15) . When the data access alignment unit 80a~80m and the subscriber line interface unit 30a~30 (m+n) are on, it moves to step 23 (S23), and thus the busy tone is off. Thereafter, the echo canceller which is in an On condition is turned off (S24) .

In step 7 (S7), when it is confirmed that the internal subscriber makes a phone call to the portable terminal, it moves to step 25 (S25) . The control unit 100 checks whether the portable terminal channels 90a~90n are full. If they are not, the control unit 100 judges whether the portable terminal channel has an error (S26) . In case the portable terminal channel does not have the error, the internal subscriber line of the private branch exchange 10 is connected to the portable terminal channel (S27). After hooking off the switch of the data access alignment unit, while the telephone number is being detected, the control unit 100 checks whether the subscriber line interface circuit unit is on (S28, S29) . As a result of the check, in case the subscriber line interface circuit unit is on, it proceeds to step 34, and thus the call is disconnected. When the telephone number is detected ("Yes" in S30) , a phone call is made to the portable terminal (S31) . The control unit 100 consecutively transmits the telephone number for a predetermined number until the portable terminal transmits a recognition signal that it accepts the call demand (S32) . When the user who calls the portable terminal side hangs up ("Yes" in S33) , the control unit 100 turns off the echo canceller on a path forming a current speech path (S34) , and disconnects both the phones (S35) .

On the other hand, when the portable terminal channels are full in step 20 (S20) , or when the portable terminal channel has an error in step 21 (S21) , it proceeds to step 36 (S36) . Accordingly, the control unit 100 transmits the busy tone (600Hz intermittent sound) and judges whether the portable terminal channels are full

(S37) . In step 37 (S37) , in case the portable terminal channels are full, the control unit 100 confirms that the subscriber line interface circuit unit 30a~30 (m+n) is on (S38) , thereby checking the call connection state. When the subscriber line interface circuit unit 30a~30 (m+n) is off, the control unit 100 judges whether the lines connected to the public switched telephone network 20 are all used. If the lines are all used ("Yes" in S39) , it proceeds to step 37 (S37).

In step 37 (S37) , when the portable terminal channels are not full, it moves to step 40 (S40) . The control unit 100 judges whether the portable terminal has an error. If the portable terminal does not have the error, the control unit 100 connects the subscriber line of the private branch exchange 10 to the empty portable terminal channel (S41) .

The call-making operation of the external subscriber to the internal subscriber (namely, the call-receiving operation of the telephone call device in accordance with the preferred embodiment of the present invention) will now be explained with reference to the flowcharts of Figures 4a and 4b.

Firstly, the control unit 100 checks whether the ring signal is inputted through the data access alignment unit 80a~80m or through the portable terminal.

In case the ring signal is inputted through the data access alignment unit 80a~80m ("Yes" in S50), the control unit 100 controls the switching control unit 70 in order to connect the line of the public switched telephone network 20 to the empty internal subscriber line (channel) of the private branch exchange 10 (S51). The echo canceller on a currently-formed speech path is turned on, and the ring signal is transmitted to the internal subscriber line through the subscriber line interface circuit unit (S52). The control unit 100 checks whether the ring signal is inputted through the data access alignment unit 80a~80m, until the extension user (namely, internal subscriber) picks up the phone (S53) .

When the ring signal is consecutively inputted through the data access alignment unit 80a~80m, the control unit 100 checks a hook on/off condition of the subscriber line interface circuit unit on the currently-formed speech path (S54). In case the subscriber line interface circuit unit is in the hook off condition, that is the extension user picks up the phone, the control unit 100 turns off the ring signal to the corresponding subscriber line interface circuit unit (S55) . Thereafter, the control unit 100 hooks off the data access alignment unit of the corresponding central office line, thereby connecting the call (S56) .

In a state where the call is connected, the control unit 100 judges whether the call is disconnected, according to the On/Off condition of the subscriber line interface circuit unit on the corresponding speech path (S57) .

In step 57 (S57) , when the subscriber line interface circuit unit is turned on, the control unit 100 recognizes that the call is disconnected, turns off the echo canceller on the corresponding speech path (S58), and hooks on the corresponding data access alignment unit (S59) .

In step 53 (S53) , in case the ring signal of the data access alignment unit is not consecutively generated, the control unit 100 turns off the ring signal to the subscriber line interface circuit unit, and it returns to step 58 (S58).

On the other hand, when the ring signal is inputted from the portable terminal HPl-HPn ("Yes" in S61), the control unit 100 controls the switching control unit 70 in order to connect the portable terminal channel 90a~90n to the empty internal subscriber line of the private branch exchange 10 (S62) . Then, the control unit 100 turns on the echo canceller on the currently-formed speech path, and transmits the ring signal to the empty internal subscriber line through the subscriber line interface circuit unit (S63) .

The control unit 100 checks whether the ring signal of the portable terminal HPl-HPn is inputted, until the internal subscriber picks up the phone (S64) . When the ring signal is consecutively inputted, the control unit 100 checks the hook on/off condition of the subscriber line interface circuit unit on the currently-formed speech path (S65) .

When the subscriber line interface circuit unit is in a hook off condition, namely the extension user picks up the phone, the control unit 100 turns off the ring signal to the corresponding subscriber line interface circuit unit (S66) . Thereafter, the control unit 100 connects the call through the corresponding portable terminal channel 90a~90n (S67).

In a state where the call is connected, the control unit 100 judges whether the call is disconnected, according to the On/Off state of the subscriber line interface circuit unit on the corresponding speech path (S68).

In step 68 (S68), if the subscriber line interface circuit unit is on, the control unit 100 recognizes that the call is disconnected, turns off the echo canceller on the corresponding speech path (S69) , and finishes the call of the portable terminal (S70) . In addition, when the ring signal of the portable terminal HPYHPn is not consecutively generated, the control unit 100 turns off the ring signal of the subscriber line interface circuit unit, and it proceeds to step 69. As discussed earlier, the telephone call device is applied to the companies or buildings provided with the private branch exchange 10. However, if necessary, it can be used at home or in other buildings.

On the other hand, in accordance with the preferred embodiment of the present invention, when the phone call is made from the extension to the central office line, the conventional method is employed. In case the phone call is made from the extension to the portable terminal or vice versa, the phone call is performed through the special exchange for the wireless communication network, without passing the conventional local telephone network. As a result, the telephone call rate is lowered, and the wireless communication companies also save the cost, thereby increasing the subscribers.

As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiment is not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the meets and bounds of the claims, or equivalences of such meets and bounds are therefore intended to be embraced by the appended claims.

Claims

1. A telephone call device comprising: a call signal processing unit for processing call signals between internal subscribers who subscribe to a private branch exchange (PBX) and external subscribers who subscribe to a public switched telephone network (PSTN); a switching control unit having a built-in exchange for a wireless communication network, for switch-controlling central office line channels and wireless channels according to transmitted and received telephone number types so that a telephone call can be performed between the internal and external subscribers through the exchange for the wireless communication network without passing a local telephone network; and a control unit for controlling the operation of the call signal processing unit and the switching control unit.

2. The telephone call device according to claim 1, wherein the call signal processing unit, the switching control unit and the control unit are integrated on a single board.

3. The telephone call device according to claim 2, wherein the board is installed at a region of a telephone terminal box where telephone lines are concentrated.

4. The telephone call device according to claim 1, wherein the switching control unit is applied to a long distance telephone network.

5. The telephone call device according to claim 1, wherein the switching control unit is applied to an international telephone network.

6. The telephone call device according to claim 1, wherein the switching control unit is applied to a cellular phone network.

7. The telephone call device according to claim 1, wherein the switching control unit is applied to a wireless telephone network.

8. The telephone call device according to claim 1, wherein the switching control unit is applied to a trunk radio system (TRS) network.

9. The telephone call device according to claim 1, wherein the exchanges for the wireless communication network in the switching control unit are respectively installed between internal subscriber lines and external channels that are provided correspondingly to the internal subscriber lines, and respectively include first and second exchanges units.

10. The telephone call device according to claim 9, wherein the first and second exchange units in the exchanges for the wireless communication network can transmit and receive the signals each other in the corresponding channel, and can transmit and receive the signals to and from the exchange units in another exchange for the wireless communication network.

11. A telephone call method wherein internal subscribers subscribing to a private branch exchange (PBX) make a phone call to external subscribers connected to a public switched telephone network (PSTN) through an exchange for a wireless communication network, without passing a local telephone network, according to transmitted telephone number types.

12. The telephone call method according to claim 11, wherein the exchange for the wireless communication network is applied to a long distance telephone network.

13. The telephone call method according to claim 11, wherein the exchange for the wireless communication network is applied to an international telephone network.

14. The telephone call method according to claim 11, wherein the exchange for the wireless communication network is applied to a cellular phone network.

15. The telephone call method according to claim 11, wherein the exchange for the wireless communication network is applied to a wireless telephone network.

16. The telephone call method according to claim 11, wherein the exchange for the wireless communication network is applied to a trunk radio system (TRS) network.

17. A telephone call method wherein internal subscribers subscribing to a private branch exchange (PBX) receive a phone call from external subscribers connected to a public switched telephone network (PSTN) through an exchange for a wireless communication network, without passing a local telephone network, according to received telephone number types.

18. The telephone call method according to claim 17, wherein the exchange for the wireless communication network is applied to a long distance telephone network.

19. The telephone call method according to claim 17, wherein the exchange for the wireless communication network is applied to an international telephone network.

20. The telephone call method according to claim 17 , wherein the exchange for the wireless communication network is applied to a cellular phone network.

21. The telephone call method according to claim 17, wherein the exchange for the wireless communication network is applied to a wireless telephone network.

22. The telephone call method according to claim 17 , wherein the exchange for the wireless communication network is applied to a trunk radio system (TRS) network.