JP4401179B2 - Network telephone equipment - Google Patents

Description

  The present invention relates to a network telephone device for exchanging voice signal packets via a network and performing a voice call via the network.

  In recent years, so-called IP telephones that directly exchange audio signals using a network, particularly the Internet, have begun to spread widely, and various configurations have been proposed (for example, see Patent Document 1 below). Such an IP telephone is specified as VoIP (Voice over Internet Protocol) in the Internet, and exchanges voice signals and packets between a telephone apparatus having a transmission / reception function and a network. The exchange of voice via is realized. In addition, since IP telephones are specified so that emergency calls cannot be used due to their nature, when using IP telephones for home use, it is necessary to use them together with ordinary telephone lines. In this case, it is inconvenient for the user to provide a service such as a telephone call via a normal telephone line and a service as an IP telephone via a network by using different telephones. A connection function, a so-called gateway function, is provided, and a single device is used to support both services. Therefore, IP telephones having such a gateway function are required to cope with services provided via public telephone lines.

Japanese Patent Application No. 10-261518

  The operation required as the function of such a gateway is considered to be four line connection states of incoming / outgoing of an IP telephone and incoming / outgoing from a normal telephone line. In addition to these, it is necessary to cope with various services provided via a normal telephone line, for example, services such as emergency calls, toll-free numbers, and connections to a facsimile communication network. In addition to the call, other services such as number display, name display, and L mode exist as incoming services from the telephone office.

  Therefore, when trying to support these services with a conventional IP telephone, the connection circuit connected to the public telephone line determines whether to provide these services, responds to signals that identify each service, or provides necessary signals. Is provided to the telephone device side.

  However, since the services provided via the public telephone line are diverse as described above, there is a problem that a complicated circuit or program must be prepared in order to analyze and respond to all of these services. Of course, if a contact circuit such as a relay is prepared and the public telephone line and the telephone device are directly connected, it is not necessary to interpret the service via the public telephone line by the IP telephone. However, if the connection is switched using a contact such as a relay, the impedance to the line changes, and the exchange connected to the public telephone line malfunctions. Therefore, the direct connection by switching the relay contact is not allowed except for the circuit configuration as an emergency telephone in an emergency.

The network telephone device of the present invention that solves at least a part of the above problems is as follows.
A network telephone device for exchanging voice signal packets over a network to make a voice call over the network,
Alone can process telephone device services and audio signals are provided via the public telephone line is connected, between the said telephone apparatus to input and output audio signals and control signals for said service And a signal processing circuit for a telephone device for converting the voice signal and the PCM signal,
Packet conversion processing for converting between the PCM signal input / output by the telephone device signal processing circuit and the voice signal packet exchanged with the network side between the telephone device signal processing circuit and the network Circuit,
Connected to the public telephone line, receives a signal transmitted through the public telephone line, inputs / outputs a voice signal to / from the public telephone line, and converts the voice signal and the PCM signal A line side signal processing circuit for performing
Detection for detecting a signal designating a service provided via the public telephone line or a signal notifying the start of the service by analyzing a signal at the time of reception received by the line side signal processing circuit and converted into the PCM signal Circuit,
When one of the signals is detected by the detection circuit, the PCM signal input / output by the line side signal processing circuit and the PCM signal input / output by the signal processing circuit for telephone apparatus are connected by a non-contact circuit. Then, the gist of the present invention is that it includes a connection circuit that connects the public telephone line side and the telephone device via the line side signal processing circuit and the telephone device signal processing circuit.

According to such a network telephone device, when a signal received by the line-side signal processing circuit is analyzed and a signal for notifying a service provided through the public telephone line or a service start is detected, A line signal processing circuit that inputs and outputs voice signals between the telephone device and a signal processing circuit for telephone devices that inputs and outputs voice signals at least by a contactless circuit. A telephone apparatus is connected via the line side signal processing circuit and the telephone apparatus signal processing circuit . Therefore, thereafter, the public telephone line side and the telephone apparatus can directly exchange signals, and various services via the public telephone line can be performed using the functions of the telephone apparatus side. As a signal for informing the start of such service, for example, there is a signal for inverting the polarity of the line. For example, in the case of fax communication, it is easy to detect the start of a service using a CNG signal output at the start. In addition to this, it is possible to use a signal indicating a service start predetermined for various services.

  In such a network telephone device, the service to be detected can be assumed to be at least one of free dial, facsimile communication network, number display, name display, and L mode.

  Furthermore, after connecting the public telephone line and the telephone device, it is provided with service end detection means for detecting the end of the service supported by the telephone device, and when the end of the service is detected, the line side signal via the contactless circuit If the connection between the processing circuit and the telephone signal processing circuit is released, it is possible to easily cope with the end of the service.

  In addition, such a network telephone apparatus is preferably provided with a contact circuit that forms a circuit for directly connecting the public telephone line and the telephone apparatus in an emergency such as a power failure. Since the operation of the circuit that operates electrically is necessary for the connection by the connection circuit, the telephone device is used in the event of an emergency such as a power outage by adopting a configuration in which both are connected by a direct contact circuit in the event of a power outage It becomes possible to do.

  Embodiments for carrying out the present invention will be described based on examples. FIG. 1 is a block diagram showing an internal configuration of a network telephone device 10 as an embodiment of the present invention. As shown in the figure, this network telephone device 10 has functions such as a microprocessor unit (MPU) 20 that controls the entire system, a network interface 30 that exchanges data with the Internet, a hub that connects a LAN, and NAT. LAN controller 35 to be realized, digital signal processor (DSP) 40 dedicated to processing audio signals, data access arrangement circuit (DAA) 50 which is an interface module for public telephone lines, and subscriber line which is an interface module for telephone 60 An interface circuit (SLIC) 70, a mechanical switch 80 that directly connects the public telephone line PT and the telephone 60 in an emergency, and the like. The MPU 20 incorporates a ROM and a RAM, and executes various types of controls described later, such as the DAA 50 and the SLIC 70, by executing a program prepared in advance. The connection function, that is, the function as a router is also realized. Since these functions are well known as network telephone devices having a LAN function, detailed description thereof is omitted.

  The DAA 50 is a circuit that converts an analog signal flowing through the public telephone line PT into a digital signal and outputs it to the DSP 40, or converts a digital signal from the DSP 40 into an analog signal and outputs it to the public telephone line PT. Data is exchanged between the DAA 50 and the DSP 40 in the form of a 1-bit serial signal (PCM). Similarly, the SLIC 70 converts the audio signal input from the microphone 62 of the telephone set 60 connected to the telephone port 61 into a digital signal, and outputs the digital signal to the DSP 40 as a 1-bit serial signal, while the serial signal from the DSP 40 is converted. It is received, converted into an analog signal, and output. This analog signal is output to the telephone 60 and used in the telephone 60. The analog signal includes an audio signal, but also includes other control signals. The telephone 60 has a function corresponding to a normal telephone service, for example, a free dial, a number display, a name display, a connection service with a facsimile communication network, an L mode connection service, and the like. Of course, the telephone 60 is also provided with a numeric keypad 66 and a display 68, and the user can perform a call operation using the telephone 60. These numeric keys 66 and on-hook signals are also exchanged via the SLIC 70.

  The network interface 30 is a normal interface circuit and supports a protocol such as so-called TCP / IP. In the case of functioning as a so-called IP telephone, the audio signal from the telephone 60 is converted into a digital signal by the SLIC 70, encoded by the DSP 40, converted into a packet by the MPU 20, and sent from the network interface 30 to the Internet. . Conversely, if a packet received as an IP telephone is included in a packet received via the Internet, a signal is transmitted from the network interface 30 to the SLIC through a route opposite to the above route, and the speaker 64 is sounded.

  Next, the internal configuration of the DSP 40 will be described with reference to FIG. FIG. 2 is a block diagram showing the internal configuration of the DSP 40. As shown in the figure, the DSP 40 includes a PCM interface circuit 41 that controls serial communication with the DAA 50 and the SLIC 70, an echo canceller circuit 42 that extracts a signal for echo cancellation from signals exchanged with the PCM interface circuit 41, and an echo canceller circuit 42. A tone detection circuit 43 for detecting a tone signal for calling from an output signal, a dedicated codec circuit 44 for amplifying a voice signal output from the echo canceller circuit 42 by an amplifier AMP and encoding for the voice, a codec circuit 44 and an MPU interface 45, a tone generator 47 that generates a tone signal for calling based on a signal from the MPU interface 45, and a dedicated packet that detects a fax signal. Fax signal controller 48 which generates the door, and a through mode controller 49 or the like corresponding to a part of the detection circuit and connection circuit of the present invention.

  The codec circuit 44 is a circuit that encodes and decodes a PCM signal and a packet. The DSP 40 uses the codec circuit 44 to convert between a PCM signal, which is a digital signal (1 bit) handled by the SLIC 70, and a packet handled as an IP telephone protocol on the network side. Specifically, the PCM signal received from the SLIC 70 via the echo canceller circuit 42 is encoded into a packet that can be handled by the TCP / IP protocol as an IP telephone by the codec circuit 44 and received from the network side. The packet as the IP telephone is finally decoded into a PCM signal for reproduction by the telephone 60. The codec circuit 44 exchanges such packets with the MPU 20 via the packet controller 46 and the MPU interface 45, and as a result, realizes the function of an IP phone using a network.

  Next, the circuit configuration of the DAA 50 and the SLIC 70 and the connection of the mechanical switch 80 will be described. FIG. 3 is a block diagram showing the internal configuration of the DAA 50 and the SLIC 70. As shown in the figure, the DAA 50 is separated by a 2/4 line converter 52 that separates a signal input from a 2-line public telephone line PT through a port 51 into 4 lines, and the 2/4 line converter 52. An ADC 53 that is an A / D converter that inputs a received voice signal Rx and converts it into a 1-bit digital signal, a PCM interface 54 for connection with the DSP 40, and a PCM signal received from the DSP 40 side via the PCM interface 54 DAC 55 which is a D / A converter for converting to transmission voice signal Tx, polarity detection circuit 56 for detecting polarity reversal of public telephone line PT, ringing detection circuit 57 for detecting a call signal via public telephone line PT, on-hook Call control circuit 58 for generating a dial pulse and the like, and control between these circuits 56, 57, 58 and MPU 20 Equipped with a SPI interface 59 to mediate the issue.

  In the circuit shown in FIG. 3, the audio signal received via the public telephone line PT is converted to a digital signal via the 2/4 line converter 52 and the ADC 53, and as a code-modulated signal by the PCM interface 54. It is output to the DSP 40. On the other hand, the audio signal output from the DSP 40 as a PCM signal is received by the PCM interface 54, converted into an analog signal by the DAC 55, and then sent to the public telephone line PT via the 2/4 line converter 52. Is output. Therefore, the DAA 50 can perform bidirectional conversion between the voice signal on the public telephone line PT and the PCM signal handled by the DSP 40 by the operation of the call control circuit 58 and the like. Note that a polarity inversion signal, a called signal, and the like that are received from the public telephone line PT are also detected by the polarity detection circuit 56 and the ringing detection circuit 57. However, like the voice signal, they are passed through the 2/4 line converter 52 and the ADC 53. Are converted into digital signals and output to the DSP 40 via the PCM interface 54. Further, since the incoming call from the public telephone line PT cannot be received while the telephone 60 is in use, the call control circuit 58 is operated via the SPI interface 59 by a signal from the MPU 20 that detects the use of the telephone 60, Control is also performed to keep the DAA 50 busy as viewed from the public telephone line PT.

  On the other hand, the SLIC 70, like the DAA 50, is connected to the telephone port 61 via the contact of the mechanical switch 80, or between the 2/4 line converter 72 and the PCM interface 74. An ADC 73 and a DAC 75 that perform digital-analog conversion in each direction are provided. In addition, the SLIC 70 includes a ring generation circuit 78, an SPI interface 79, a DC / DC converter 71, and the like. The ring generation circuit 78 is a circuit that generates a ring signal for ringing the telephone set 60. The SPI interface 79 is an interface circuit that exchanges signals with the MPU 20 and operates the ring generation circuit 78 and the like at a predetermined timing. Further, the DC / DC converter 71 is a circuit that generates a DC voltage of 48 volts or 90 volts necessary for the operation of the telephone set 60.

  The output of the 2/4 line converter 72 of the SLIC 70 is connected to the telephone port 61 via the contact of the mechanical switch 80 as described above. This mechanical switch 80 is provided to enable the telephone 60 to be directly connected to the public telephone line PT in an emergency such as a power failure. The mechanical switch 80 has two circuit transfer contacts, and when the power supply voltage is supplied, the terminal on the side to which the signal line of the public telephone line PT is connected is opened, and the signal line from the telephone port 61 is connected. , Connected to the 2 / 4-wire converter 72 of the SLIC 70. On the other hand, when the power supply to the mechanical switch 80 is cut off due to a power failure or the like, the contact is switched to the opposite side, and the signal line from the public telephone line PT is directly connected to the telephone 60 via the telephone port 61. Become. In this state, it is possible to make an emergency call from the telephone 60 via the public telephone line PT.

  Next, the operation of the through mode controller 49 and how to receive various services from the public telephone line PT will be described with reference to FIG. FIG. 4 is an explanatory diagram schematically showing how the PCM signal lines of the DAA 50 and the SLIC 70 are connected in the PCM interface circuit 41 of the DSP 40 and controlled by the through mode controller 49. First, connection of signal lines will be described. The PCM signal output from the DAA 50 is connected to the through mode controller 49 via the PCM interface circuit 41 and also connected to one input terminal of the 2-input AND gate 91 in the PCM interface circuit 41. A control signal from the through mode controller 49 is connected to the other input terminal of the 2-input AND gate 91. The output of the 2-input AND gate 91 is connected to one input terminal of the 2-input OR gate 92. The other input terminal of the two-input OR gate 92 is connected to the output of another two-input AND gate 93. The two-input AND gate 92 is connected to one input terminal of a signal output from the codec circuit 44 (not shown, but this signal is a signal converted into a PCM signal by the PCM interface circuit 41). A signal obtained by inverting the control signal by the inverter 94 from the through mode controller 49 is input to the other input terminal.

  Since control signals whose states have been inverted by the inverter 94 are input to one input terminal of each of the two two-input AND gates 91 and 93, the two two-input AND gates 91 and 93 are eventually connected. The output of the OR gate 92 that receives the output is either the other input signal of the two-input AND gates 91 and 93, that is, the PCM signal output from the DAA 50 or the PCM signal output from the codec circuit 44. It is alternatively output. This signal becomes the PCM signal input to the SLIC 70.

  On the other hand, the PCM signal output from the SLIC 70 is connected to one input terminal of each of the two 2-input AND gates 96 and 97. A control signal output from the through mode controller 49 and a signal obtained by inverting it with an inverter 98 are connected to the other input terminal of each of these two 2-input AND gates 96 and 97. Therefore, these two 2-input AND gates 97 and 98 and the inverter 94 function as a selector that outputs a signal alternatively depending on the state of the control signal from the through mode controller 49. Accordingly, the PCM signal output from the SLIC 70 is either a PCM signal directly input to the DAA 50 or output to the echo canceller circuit 42 of the DSP 40 according to a control signal output from the through mode controller 49.

  Since the PCM signal output from the DAA 50 is always input to the through mode controller 49, the through mode controller 49 can easily grasp the state on the public telephone line PT side by monitoring this signal. Normally, when the DAA 50 arrives at the public telephone line PT side, the polarity of the line is reversed, so this is detected and transmitted to the MPU 20 via the SPI interface 59, and the fact that the polarity reversal has occurred is converted into a digital signal by the ADC 53. This is converted into a predetermined code by the PCM interface 54 and output as a PCM signal. When detecting the sign, the through mode controller 49 inverts the control signal that has been inactive (low level) until then to active (high level). If the control signal output from the through mode controller 49 is inactive, that is, low level, the outputs of the two-input AND gates 91 and 96 are invalid and the outputs of the two-input AND gates 93 and 97 are valid. As a result, as shown in FIG. 5, the PCM signal of the SLIC 70 is connected only to the DSP 40. From this state, when the control signal of the through mode controller 49 is inverted to active (ie, high level), the PCM signal of the SLIC 70 is directly connected to the DAA 50 as shown in FIG. Moreover, at this time, unlike the switching by the mechanical switch 80, since the flow of the PCM signal is switched, there is no change in impedance as seen from the public telephone line. For this reason, no malfunction occurs on the exchange side operating the public telephone line PT.

  In the state shown in FIG. 6, all signals received from the public telephone line PT are once converted into PCM signals by the DAA 50 and output to the SLIC 70 via the PCM interface circuit 41 as they are. The SLIC 70 demodulates the original signal from the PCM signal and outputs it to the telephone set 60. Accordingly, various services such as connection to a name display and a facsimile communication network provided through the public telephone line PT are all processed by the telephone 60 corresponding to these functions. Originally, these services can be used only when the function is provided on the telephone 60 side. Therefore, there is no problem as a configuration in which all signals are passed from the DAA 50 to the SLIC 70. As a result, it is not necessary to perform signal analysis on the DSP 40 side or MPU 20 side in accordance with various services, and software for performing these analyzes can be omitted.

  In the present embodiment, the number display service is determined by the MPU 20 and rejects incoming calls. Therefore, the PCM signal output from the DAA 50 is constantly monitored on the MPU 20 side (see FIG. 4). There is nothing wrong with taking such a response. Also, by adopting such a configuration, the MPU 20 side can grasp the state of the DAA 50, so that it is possible to respond promptly and appropriately when an unexpected interruption of service occurs. In this embodiment, the through mode controller 49 reads the PCM signal output from the DAA 50 and directly switches the control signal. However, the MPU 20 may have the function of the through mode controller 49. When a telephone call is made through a network, when the telephone 60 is used as a so-called IP telephone, an incoming call from the public telephone line PT is not normally received. The call control circuit 58 shown in FIG. 3 may be controlled from the MPU 20 side to make the public telephone line PT side busy. Of course, the PCM signal output from the DAA 50 may be monitored, and after receiving an incoming call, a response indicating that it is busy may be made.

  As mentioned above, although one Example of this invention was described, this invention is not limited to such an Example, Of course, in the range which does not change the summary of this invention, it can implement in a various aspect. . For example, in this embodiment, the switching of the PCM signal between the DAA 50 and the SLIC 70 is configured using a logic circuit, but may be configured by an analog switch, a data selector, or the like.

It is a block diagram which shows schematic structure of the network telephone apparatus 10 which is one Example of this invention. 2 is a block diagram showing an internal configuration of a DSP 40. FIG. 3 is a block diagram showing an internal configuration of DAA 50 and SLIC 70 and a connection state by mechanical switch 80. FIG. It is a circuit diagram which shows an example of the circuit structure which connects DAA50 and SLIC70 by a PCM signal. It is explanatory drawing which shows the connection state of the PCM signal at the normal time. It is explanatory drawing which shows the connection state of the PCM signal at the time of the incoming call from the public telephone line PT side.

Explanation of symbols

10 ... Network telephone device 20 ... MPU
30 ... Network interface 35 ... LAN controller 40 ... Digital signal processor (DSP)
41 ... PCM interface circuit 42 ... Echo canceller circuit 43 ... Tone detection circuit 44 ... Codec circuit 45 ... MPU interface 46 ... Packet controller 47 ... Tone generator 48 ... Fax signal controller 49 ... Through mode controller 50 ... DAA
51 ... Port 53 ... ADC
54 ... PCM interface 54 ... PCM interface circuit 55 ... DAC
DESCRIPTION OF SYMBOLS 56 ... Polarity detection circuit 57 ... Ringing detection circuit 58 ... Call control circuit 59 ... SPI interface 60 ... Telephone 61 ... Telephone port 62 ... Microphone 64 ... Speaker 66 ... Numeric keypad 70 ... SLIC
71 ... DC / DC converter 73 ... ADC
74 ... PCM interface 75 ... DAC
78 ... Ring generation circuit 79 ... SPI interface 80 ... Mechanical switch 91, 93, 96, 97 ... 2-input AND gate 92 ... OR gate 94, 98 ... Inverter AMP ... Amplifier PT ... Public telephone line Rx ... Received voice signal Tx ... Transmission Audio signal

Claims (4)

A network telephone device for exchanging voice signal packets over a network to make a voice call over the network,
Alone can process telephone device services and audio signals are provided via the public telephone line is connected, between the said telephone apparatus to input and output audio signals and control signals for said service And a signal processing circuit for a telephone device for converting the voice signal and the PCM signal,
Packet conversion processing for converting between the PCM signal input / output by the telephone device signal processing circuit and the voice signal packet exchanged with the network side between the telephone device signal processing circuit and the network Circuit,
Connected to the public telephone line, receives a signal transmitted through the public telephone line, inputs / outputs a voice signal to / from the public telephone line, and converts the voice signal and the PCM signal A line side signal processing circuit for performing
Detection for detecting a signal designating a service provided via the public telephone line or a signal notifying the start of the service by analyzing a signal at the time of reception received by the line side signal processing circuit and converted into the PCM signal Circuit,
When one of the signals is detected by the detection circuit, the PCM signal input / output by the line side signal processing circuit and the PCM signal input / output by the signal processing circuit for telephone apparatus are connected by a non-contact circuit. And a connection circuit for connecting the public telephone line side and the telephone device via the line side signal processing circuit and the telephone device signal processing circuit. The network telephone device according to claim 1, wherein
The network telephone apparatus in which the service detected by the detection circuit is at least one of free dial, facsimile communication network, number display, name display, and L mode. The network telephone device according to claim 1, wherein
The detection circuit includes service end detection means for detecting the end of the service provided in a state where the public telephone line and the telephone device are connected, and when the end of the service is detected, the contactless circuit A network telephone device for releasing connection between the line-side signal processing circuit and the telephone device signal processing circuit via a network. The network telephone device according to claim 1, wherein
A network telephone device comprising a contact circuit for forming a circuit for directly connecting the public telephone line and the telephone device in an emergency such as a power failure.

Images