JP2006287541A - VoIP GATEWAY DEVICE AND TRANSFER PROCESSING METHOD - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the speed of transfer processing of voice data for use in speech. <P>SOLUTION: A transfer processing part 13 calculates a channel port of a multiple signal corresponding to an RTP port number. In this case, the channel number is calculated from the RTP port number on the basis of an expression (channel number)=((RTP port number)-(offset value)/(interval value)). Before or after calculation of the channel number, voice data is acquired from a voice packet stored in a buffer and is converted to voice data conforming to an encoding system used in a telephone controller 3. The converted voice data is stored into the multiple signal as channel data of the channel number calculated from the RTP port number. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a VoIP communication technique, and more particularly to a technique for transferring voice data stored in a voice packet received from an IP network to a channel provided in a time division manner on a multiplexed signal.

VoIP communication that performs a voice call over an IP network is being used in a telephone system that accommodates multiple lines such as PBX from the viewpoint of reducing communication costs. When VoIP communication is used in such a telephone system, a conventional telephone line interface provided in the telephone system and an IP network and a so-called VoIP gateway apparatus are used.
This type of telephone system includes a dedicated line interface for digital relay lines such as TTC-2M, for example, in order to efficiently transmit voice for multiple lines. This leased line interface is a multiplex transmission method in which data obtained by encoding a voice signal of each call is stored and transmitted in a channel (slot) provided in a time division manner on the multiplex signal.

  The VoIP gateway device is provided with such a dedicated line interface and efficiently accommodates multiple lines from the telephone system. In this case, in the VoIP gateway device, it is necessary to transfer the voice data stored in the voice packet received from the IP network to a channel provided in a time division manner on the multiplexed signal.

Usually, when a voice packet is transferred via an IP network, a packet transfer protocol called RTP (Realtime Transport Protocol) is used. In this RTP, identification information called RTP port numbers is used as information for identifying individual calls.
Therefore, the VoIP gateway device manages the correspondence relationship between the RTP port number of the voice packet and the channel number of the channel, and the voice data stored in the voice packet received from the IP network corresponds to the RTP port number. It is necessary to switch to the channel of the channel number to be used.

  Conventionally, in such a packet data transfer process, as a technique for determining the transfer destination, a technique for searching for a transfer destination port from the MAC address of a received packet has been proposed (see, for example, Patent Document 1). This uses a part of the MAC address of the packet as the storage destination address in advance, stores the port number to which the packet of the MAC address is to be transferred in the storage location corresponding to the storage destination address, and receives the packet. A desired port number is obtained by referring to the memory using a part of the MAC address of the packet as an address.

JP 11-191784 A

  However, when such a conventional technique is used in the transfer process in the VoIP gateway device, it is necessary to refer to the memory for each transfer process of the received voice packet, which not only hinders the speeding up of the transfer process. There is a problem that an expensive memory having a high access speed is required, and a high-performance and inexpensive VoIP gateway device cannot be realized.

  Further, according to the prior art, it is necessary to use a certain bit width (for example, 16 bits = 65536) so that some bits of the MAC address used as the storage destination address do not have the same value between different calls. A memory having a storage area corresponding to the bit width is required. However, a huge storage area is required in comparison with the number of calls that can be identified by about 4 to 8 bits, for example, several tens of channels to several hundreds of channels. There is a problem that it is necessary and hardware resources cannot be used efficiently.

  An object of the present invention is to provide a VoIP gateway device and a transfer processing method capable of speeding up transfer processing of voice data used for a call.

  In order to achieve such an object, a VoIP gateway device according to the present invention includes a network interface unit that performs VoIP communication by transmitting and receiving packets based on the RTP packet communication protocol via an IP network, and a dedicated line. Voice between a dedicated line interface unit for data communication with a telephone system using a plurality of communication lines using channels provided in a time division manner on multiplexed signals to be transmitted and received, and between the network interface unit and the dedicated line interface unit A VoIP gateway device having a transfer processing unit that transfers voice data encoded with a signal to each other for each call, and is included in a voice packet of an arbitrary call received by the network interface unit in the transfer processing unit The channel number used in the call is calculated from the RTP port number by a predetermined calculation. And, in which to output the private line interface unit to store the audio data to be transferred into the channel on the multiplexed signal corresponding to the channel number.

  At this time, the transfer processing unit uses an offset value consisting of an integer value and an interval value consisting of an integer value other than 0, and an RTP port number based on the equation of channel number = (RTP port number−offset value) / interval value. From this, the channel number may be calculated.

  The transfer processing method according to the present invention also includes a network interface unit that performs VoIP communication by transmitting and receiving packets based on the RTP packet communication protocol over an IP network, and a multiplexed signal transmitted and received via a dedicated line. A dedicated line interface unit that performs data communication with a telephone system that uses a plurality of communication lines using channels provided by division, and audio data that encodes an audio signal between the network interface unit and the dedicated line interface unit A transfer processing method of a VoIP gateway apparatus having a transfer processing unit for transferring each call individually, from the RTP port number included in the voice packet of an arbitrary call received by the network interface unit by the transfer processing unit Calculating a channel number to be used in the call by a predetermined calculation; Store audio data to be transferred channel number as in the channel on the corresponding multiplexed signal and a step of outputting to the dedicated line interface.

  At this time, the transfer processing unit uses an offset value consisting of an integer value and an interval value consisting of an integer value other than 0, and an RTP port number based on the equation of channel number = (RTP port number−offset value) / interval value. The method may further comprise a step of calculating a channel number from

  According to the present invention, the transfer processing unit calculates the channel number used in the call by a predetermined calculation from the RTP port number included in the voice packet of the arbitrary call received by the network interface unit, and corresponds to the channel number. Since the voice data to be transferred in the channel on the multiplexed signal is stored and output to the dedicated line interface unit, the channel number corresponding to the RTP port number can be derived by a very simple calculation without referring to the memory. .

  Therefore, it is not necessary to refer to the memory for each transfer process of the received voice packet, and it can be replaced with an extremely simple arithmetic process such as four arithmetic operations for integers, which speeds up the transfer process or reduces the processing load on the DSP or CPU. it can. Moreover, it is not necessary to use an expensive memory with a high access speed for high-speed transfer processing, and a high-performance and inexpensive VoIP gateway device can be realized.

Next, embodiments of the present invention will be described with reference to the drawings.
[VoIP gateway device]
First, a VoIP gateway device according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of a VoIP gateway device according to an embodiment of the present invention.

The VoIP gateway device 1 is connected to the IP network 5 via the access line 10 and is connected to the telephone control device 3 of the telephone system 2 via the dedicated line 20. Is a communication processing device that transfers voice data used for a call between each other.
The telephone system 2 includes, for example, a telephone control device 3 corresponding to a main unit of a private branch exchange (PBX) and a key telephone device, and a plurality of telephones 4 accommodated in the telephone control device 3 via an extension line 30. In this system, the telephone control device 3 exchanges and connects the telephone line 4 and the telephone line multiplexed as a channel to the dedicated line 20. Note that the telephone system 2 used in the present embodiment is a system using a general known technique, and a detailed description thereof is omitted here.

A voice packet received from the access line 10 uses a packet transfer protocol called RTP (Realtime Transport Protocol) that uses identification information called RTP port numbers as information for identifying individual calls. On the other hand, the leased line interface used in the leased line 20 is a multiplex that stores and transmits voice data obtained by encoding a voice signal of each call in a channel (slot) provided in a time division manner on the multiplexed signal. Transmission system.
Therefore, the VoIP gateway device 1 manages the correspondence between the RTP port number of the voice packet and the channel number of the channel, and converts the voice data stored in the voice packet received from the IP network 5 to the RTP port number. Transfer processing is performed to transfer to the channel of the channel number corresponding to.

  In the present embodiment, when the VoIP gateway device 1 transfers the voice data stored in the voice packet received from the access line 10 to the channel on the multiplexed signal of the dedicated line 20, it is given to the voice packet. The channel number of the storage destination is calculated by calculating the RTP port number being stored, and the voice data to be transferred is stored in the channel of that channel number.

  The VoIP gateway device 1 is a communication device that performs various types of communication control with a computer. A network interface unit (hereinafter referred to as a network I / F unit) 11, a dedicated line interface unit (hereinafter referred to as a dedicated line I / F unit) 12, A transfer processing unit 13 and a call control unit 14 are provided.

  The network I / F unit 11 is a circuit unit that performs termination control of the access line 10 and transmits and receives voice packets and control packets for VoIP communication. The network I / F unit 11 transmits the voice packets and control packets output from the transfer processing unit 13 to the access line. 10 and a function of outputting a voice bucket and control packet received from the access line 10 to the transfer processing unit 13.

FIG. 2 is a configuration example of a packet transmitted and received by the network I / F unit. Main information stored in the packet 200 includes a transmission source address 201, a destination address 202, an RTP port number 203, and user data 204.
The transmission source address 201 is IP protocol address information indicating the transmission source terminal device of the packet. The destination address 202 is IP protocol address information indicating the destination terminal device of the packet. The RTP port number 203 is identification information for identifying each call in the RTC protocol used for VoIP communication. The user data 204 is arbitrary data to be transferred in the packet. The voice data is stored in the voice packet, and the control data is stored in the control packet.

  The dedicated line I / F unit 12 is a circuit unit that performs termination control of the dedicated line 20 and transmits / receives voice data and control data for calls, and multiplexes the voice data and control data output from the transfer processing unit 13. There is a function of storing in the corresponding channel above and transmitting it to the dedicated line 20 and a function of capturing voice data and control data from each channel on the multiplexed signal received from the dedicated line 20 and outputting them to the transfer processing unit 13. is doing.

  FIG. 3 is a configuration example of a multiplexed signal transmitted and received by the dedicated line I / F unit. The multiplexed signal 300 is provided with a frame 301 having a fixed time length synchronized with a predetermined timing, and a plurality of channels (slots) are provided in the frame 301 in a time division manner. Audio data and control data are stored in this channel. For example, in a dedicated line interface (digital trunk) called TTC-2M, 32 channels are provided in one frame, and are transmitted and received at a transfer rate of 2048 Kbit / s as a whole.

  The transfer processing unit 13 is a functional unit that performs transfer processing for transferring various packets and data between the network I / F unit 11 and the dedicated line I / F unit 12, for example, DSP (Digital Signal Processor: DSP). A digital signal processing device) or a microprocessor such as a CPU and its peripheral circuits, and by executing programs read from the microprocessor and memory of the peripheral circuits to perform various signal processing and information processing, To achieve various functions.

  The main functions realized by the transfer processing unit 13 include a function for converting the encoding method of the audio data included in the audio packet of an arbitrary call from the network I / F unit 11, and the converted audio. A function for storing data in a channel on a multiplexed signal corresponding to an RTP port number included in the voice packet and outputting the same to a dedicated line I / F unit 12, and an arbitrary call from the dedicated line I / F unit 12 The function of converting the encoding method of the voice data stored in the channel of the channel, and the converted voice data are stored in the voice packet including the RTP port number corresponding to the channel number and output to the network I / F unit 11 A function to output the control packet from the network I / F unit 11 and the control data from the dedicated line I / F unit 12 to the call control unit 14, and the control packet from the call control unit 14 including the RTP port number A function of outputting to the network I / F unit 11, a function of storing and outputting the control data from the call control unit 14 to the channels on the multiplexed signal to the dedicated line I / F section 12.

  The call control unit 14 is a functional unit that performs call control of VoIP communication using the IP network 5 and call control with the telephone system 2, and includes, for example, a microprocessor such as a CPU and its peripheral circuits. Various functions for transfer processing are realized by executing various kinds of information processing by executing programs read from the memory of the processor and peripheral circuits.

  The main function realized by this call control unit 14 is that of VoIP communication using the IP network 5 by exchanging control packets with the IP network 5 side via the transfer processing unit 13 and the network I / F unit 11. Call control between the telephone control device 3 by exchanging control data with the telephone control device 3 of the telephone system 2 via the transfer processing unit 13 and the dedicated line I / F unit 12. A function for performing protocol conversion between the IP network 5 side and the telephone control device 3 side, and a function for calculating the RTP port number used in VoIP communication from the channel number of the channel used in the call when VoIP communication is connected. have.

[Operation of VoIP gateway device]
Next, the operation of the VoIP gateway device according to this embodiment will be described with reference to FIG. FIG. 4 is a flowchart showing a packet reception operation of the VoIP gateway device according to this embodiment.
When the call control unit 14 of the VoIP gateway device 1 starts VoIP communication in response to a request from the telephone control device 3, an identification for identifying that the voice packet transmitted from the other party is that of the call An RTP port number is generated as information and notified to the call partner.

At that time, the call control unit 14 calculates the RTP port number based on the following equation (1) using the channel number on the dedicated line 20 used for the call. In equation (1), the interval value is an integer other than 0, and the offset value is an integer.
RTP port number = channel number × interval value + offset value (1)
RTP stipulates that a value within a predetermined range can be arbitrarily used for the RTP port number on the receiving side that receives a voice packet.

For this reason, by calculating the RTP port number from the channel number based on the equation (1), the corresponding channel number is calculated from the RTP port number included in the received voice bucket by the following equation (2). Can be calculated.
Channel number = (RTP port number−offset value) / interval value (2)

Therefore, when receiving a voice packet for VoIP communication from the IP network 5 through the access line 10, the VoIP gateway device 1 starts a packet receiving operation shown in FIG.
First, the network I / F unit 11 stores a voice packet received from the access line 10 in a buffer (not shown) in the transfer processing unit 13 (step 100). In response to this, the transfer processing unit 13 acquires the RTP port number from the voice packet stored in the buffer (step 101).

  Subsequently, the transfer processing unit 13 calculates the channel number of the multiplexed signal corresponding to the RTP port number (step 102). At this time, the channel number is calculated from the RTP port number based on the above-described equation (2). Also, before and after the calculation of the channel number, the voice data is acquired from the voice packet stored in the buffer, and converted into the voice data of the encoding method used in the telephone control device 3 (step 103).

Next, the transfer processing unit 13 stores the converted voice data in the multiplexed signal as channel data of the channel number calculated from the RTP port number, and outputs it to the dedicated line I / F unit 12 (step 104). The packet receiving operation is terminated.
As a result, the voice data stored in the voice packet of an arbitrary call received from the access line 10 is stored in the channel on the multiplexed signal corresponding to the call from the dedicated line I / F unit 12, and the dedicated line 20 Is transmitted to the telephone control device 3 via.

FIG. 5 is an example of correspondence between RTP port numbers and channel numbers. In this case, the channel number “0” corresponds to the RTP port number “4000”, and thereafter, the channel number increases by 1 each time the RTP port number increases by 2.
In such a case, “2” may be used as the interval value of the above-described formulas (1) and (2), and “4000” may be used as the offset value. Therefore, for example, when the RTP port number of the received voice packet is “4004”, the channel number “2” is calculated from Equation (2) as follows.
Channel number = (RTP port number−offset value) / interval value (2)
= (4004-4000) / 2
= 2

  As described above, in the present embodiment, when the VoIP gateway device 1 stores the voice data stored in the voice packet received from the access line 10 in the channel on the multiplexed signal of the dedicated line 20, the voice packet is converted into the voice packet. Since the storage destination channel number is calculated by calculation from the included RTP port number, the channel number corresponding to the RTP port number can be derived by extremely simple calculation without referring to the memory.

  Therefore, it is not necessary to refer to the memory for each transfer process of the received voice packet, and it can be replaced with an extremely simple arithmetic process such as four arithmetic operations for integers, which speeds up the transfer process or reduces the processing load on the DSP or CPU. it can. Moreover, it is not necessary to use an expensive memory with a high access speed for high-speed transfer processing, and a high-performance and inexpensive VoIP gateway device can be realized.

It is a block diagram which shows the structure of the VoIP gateway apparatus concerning one embodiment of this invention. It is a structural example of the packet transmitted / received in the network I / F part of the VoIP gateway device. It is an example of a structure of the multiplexed signal transmitted / received by the dedicated line I / F part of a VoIP gateway apparatus. It is a flowchart which shows the packet reception operation | movement of the VoIP gateway apparatus concerning this Embodiment. It is a correspondence example of an RTP port number and a channel number.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... VoIP gateway apparatus, 10 ... Access line, 11 ... Network I / F part, 12 ... Dedicated line I / F part, 13 ... Transfer processing part, 14 ... Call control part, 2 ... Telephone system, 3 ... Telephone control apparatus 4 ... telephone, 5 ... IP network.

Claims (4)

A network interface unit that performs VoIP communication by transmitting and receiving packets based on the RTP (Realtime Transport Protocol) packet communication protocol via an IP network, and a channel provided in a time division manner on multiplexed signals transmitted and received via a dedicated line A dedicated line interface unit that performs data communication with a telephone system that uses a plurality of communication lines using voice, and voice data that encodes an audio signal between the network interface unit and the dedicated line interface unit for each call A VoIP gateway device having a transfer processing unit for transferring data to each other,
The transfer processing unit calculates a channel number used in the call by a predetermined calculation from an RTP port number included in a voice packet of an arbitrary call received by the network interface unit, on the multiplexed signal corresponding to the channel number Voice data to be transferred is stored in the channel and output to the dedicated line interface unit. The VoIP gateway device according to claim 1,
The transfer processing unit uses an offset value composed of an integer value and an interval value composed of an integer value other than 0, and based on the equation of channel number = (RTP port number−offset value) / interval value, from the RTP port number. The channel number is calculated. The VoIP gateway apparatus characterized by the above-mentioned. A network interface unit for performing VoIP communication by transmitting and receiving packets based on the RTP (Realtime Transport Protocol) packet communication protocol via an IP network, and a channel provided in a time-sharing manner on multiplexed signals transmitted and received via a dedicated line A dedicated line interface unit that performs data communication with a telephone system that uses a plurality of communication lines using voice, and voice data that encodes an audio signal between the network interface unit and the dedicated line interface unit for each call A transfer processing method of a VoIP gateway device having a transfer processing unit for transferring data to each other,
Calculating a channel number used in the call by a predetermined calculation from an RTP port number included in a voice packet of an arbitrary call received by the network interface unit by the transfer processing unit; and the multiplexing corresponding to the channel number Storing the audio data to be transferred in a channel on the signal and outputting the audio data to the dedicated line interface unit. The transfer processing method according to claim 3,
The transfer processing unit uses an offset value consisting of an integer value and an interval value consisting of an integer value other than 0, and from the RTP port number based on the equation of channel number = (RTP port number−offset value) / interval value. The transfer processing method further comprising the step of calculating the channel number.

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