KR200286395Y1 - Remote Central Office Line Transfer - Google Patents

Abstract

The present invention relates to a trunk line remote switching machine, and in particular, the present invention receives an arbitrary transfer telephone number and communicates with an administrator through a specific trunk line of a private exchange side, and performs a private switching unit according to a transfer operation command of an administrator who performs an authentication procedure. The switch-off operation is performed by connecting the trunk line on the PSTN line and the VoIP line on the private exchange to the VoIP G / W. The switch-on operation is performed by connecting the trunk line and the VoIP line on the private exchange to the PSTN line. A switching control telephone means for performing a switching check operation for performing a switching check operation for notifying an administrator by identifying a current switching state and resetting the Internet modem according to a modem reset command of the administrator; And a matching unit connected to the switching control telephone means and switching to a designated path according to the switching operation command of the switching control telephone means. Therefore, according to the present invention, by controlling the C.O.line remote changer remotely in an emergency state (e.g. in case of VoIP gateway or Internet overload or other service failure), it is possible to make a call (including incoming / outgoing call) through PSTN even if VoIP call is not possible. It can be effective.

Description

CO Line Remote Switching Machine {Remote Central Office Line Transfer}

The present invention relates to a CO line remote switcher, and more specifically, when an error occurs in a VoIP over Internet Protocol GateWay (VOGG / W) trunk line, when the error is notified through the gate keeper, The present invention relates to a CO line remote changer that supports incoming / outgoing calls through a PSTN line by transferring a VoIP G / W trunk line to a PSTN line.

In general, a private branch exchange (PBX) or keyphone box (hereinafter referred to as a 'private exchange') refers to an exchange facility installed in a premises such as a public office, a company, a hospital, and the like. In the private exchange, an extension telephone is connected to a subscriber line interface card (SLIC) that accepts subscribers in the premises, and a trunk card is connected to a CO line (Central Office Line) connected to the national exchange side. In order to make an outgoing call to an external CO line, a number of extension subscribers can use each other after dialing an OCC code (usually '9') and dialing an external phone number. Do it. In general, the extension lines of the subscribers connected to the private exchanges are the extension lines that accept ordinary analog phones, the keyphone lines that accept keyphone phones, and the ISDN Basic Rate Interface (ISDN BRI) that accommodates Integrated Services Digital Network (ISDN) phones. Line, a line for accommodating a digital telephone, etc., each of which is connected to a backboard of a matching device mounted in a board form on a private exchange. In addition, trunk lines connected to private exchanges include analog trunks (general CO lines), digital trunks such as E1 lines or T1 lines, and ISDN Primary Rate Interface (ISDN PRI) lines, each of which has its own unique interface. It is connected to the back board of the matching device mounted in the private exchange in the form of a board in charge of.

VoIP is the term for IP telephony technology for a set of facilities that carry voice information using the Internet Protocol (IP), but in general, VoIP is a traditional protocol based on a circuit, such as a public switched telephone network (PSTN). It does not mean that voice information is transmitted in digital form within discrete packets. The main advantage of VoIP and Internet telephony technology is that it integrates telephony services using existing IP networks, allowing telephony users to receive long-distance and international telephony services in the Internet and intranet environments for a fee.

VoIP is being used in key forums such as Cisco, Vocaltec, 3Com, and NetSpeak through the VoIP Forum to encourage the use of ITU-T H.323, the standard for transporting voice and video over IP over the public Internet or intranets within an enterprise. It is defined by equipment manufacturers.

In the case of voice calls over VoIP, private networks managed by independent companies or Internet telephony service providers (hereinafter referred to as 'separate carriers') are not guaranteed because the public network does not guarantee the same quality of service (QoS). Networks can be used to provide high quality services. In this case, the separate telecommunications operator operates a server that manages the IP address according to the other party's phone number, allowing the user to make voice calls over the Internet without separately managing the IP address according to the other party's phone number.

In order to use VoIP in a private exchange, a gateway must be installed, which receives voice data divided into packets from users and delivers it to a destination through a network such as the Internet or an intranet, or to an analog trunk, T1 or E1 interface. Use to directly connect the call to the PSTN.

In general, when a VoIP gateway is connected to a private exchange, a different access code is provided by separating a trunk line connected to the VoIP gateway from the private exchange side. For example, when an extension subscriber wants to make a voice call with the outside through a VoIP gateway, the trunk access code is assigned to '8', and the extension subscriber wants to make a call with the outside through a general trunk line connected to the PSTN. In case of assigning the CO line occupancy code as '9', use these codes separately. In addition, when the user wants to make a voice call through the VoIP gateway, communication with the other party using the VoIP can only be made and incoming calls are made through the trunk line.

To make a VoIP call, the user first picks up the handset, checks the dial tone from the private exchange, and then dials the dial number to connect to the VoIP gateway, which connects the private exchange with the TCP / IP network (the Internet). At this time, the VoIP gateway queries the routing table to see if the received number is a serviceable number. If it is not a serviceable number, it checks to see if it needs to connect to another VoIP gateway, or else it returns the information to the private exchange to induce a call over the public telephone network. If the VoIP gateway finds the Internet route corresponding to the entered number, the call can be made. For this purpose, the gateway must secure a line between the VoIP gateway of the other party. After that, the VoIP gateway on the calling side modulates the voice into IP packets and transmits the corresponding IP packets through a TCP / IP network in a given path as if they were transmitting the corresponding data packets. Receiving side VoIP gateway receiving packet type IP data recombines packet information and restores it to analog signal, route the recovered signal back to telephone form through PSTN or other private exchange in exchange office and direct call to incoming telephone. Connect. This completes the routing procedure for voice calls over the Internet. Using VoIP technology, network administrators can route phone calls over the network as they would for data, and can provide VoIP calls to users at low cost based on them.

However, there is a problem that VoIP calls are often disconnected or cannot be made due to the instability of the Internet. For example, if communication is interrupted due to VoIP gateway or Internet overload or other service failure, the user cannot make a VoIP call, and if the user wants to make a call, the user needs to try again through the PSTN line.

Accordingly, the present invention has been made to solve the above-mentioned conventional problems, and the object of the present invention is in case of emergency (for example, in case of overload or other service failure of VoIP gateway or Internet) private trunk side trunk line and private exchange. It is to provide a CO line remote changer that connects a side VoIP line to a PSTN line to enable incoming and outgoing calls through the PSTN line.

Another object of the present invention is to determine whether an abnormality of the VoIP gateway by pinging with a simple network management protocol (SNMP), and when a command (that is, a transfer command) is transmitted from a remote site, The present invention provides a trunk line remote switcher that connects a trunk trunk line and a private trunk VoIP line to a PSTN line.

1 is a block diagram showing the connection between the internal configuration of the CO line remote changer and the peripheral device according to the present invention,

Figure 2 is a block diagram showing the internal configuration and connection of the trunk line changer according to the present invention,

3 is a flowchart illustrating a control operation of a trunk line remote changer according to the present invention.

♣ Explanation of symbols for the main parts of the drawing ♣

100: private exchange 200: trunk line transfer machine

210: switching means telephone control unit 220: matching unit

300: PSTN 400: VoIP G / W

450: Internet modem 500: Internet

600: G / K

The present invention for achieving the above object is that the PSTN line is connected to the trunk line of the private exchange side and the VoIP G / W and the Internet are connected to the VoIP line of the private exchange side to make an incoming call through the PSTN line, and through the VoIP line It is located between G / K and VoIP G / W and the Internet that checks the status of network connection and abnormality of VoIP G / W by making outgoing call and pings VoIP G / W. In a VoIP call system including an Internet modem which modulates and demodulates data in order to match the format of data exchanged between VoIP G / W and the Internet. The trunk line of the private exchange side is connected to the PSTN line according to the transfer operation command of the administrator who performs the authentication procedure and communicates with the administrator. Transition-off operation by connecting to VoIP G / W, switching-over operation by connecting trunk line of private exchange and VoIP line of private exchange to PSTN line Switching means for performing the checking operation and resetting the Internet modem according to the modem reset command of the administrator; And a matching unit connected to the transfer control telephone means and switching to a designated path according to the transfer operation command of the transfer control telephone means.

Hereinafter, with reference to the accompanying drawings, a preferred embodiment for a CO line remote switching machine according to the present invention will be described in detail.

1 is a block diagram showing the connection between the internal configuration of the CO line remote changer 200 and the peripheral device according to the present invention, the CO line remote changer 200 is largely the switching means telephone control unit 210 and the matching unit 220 ), And the matching unit 220 is composed of a C / O matching unit 221 and a G / W (GateWay) matching unit 222. The private exchange (PBX) 100 and the PSTN 300 are connected to the C / O matching unit 221, and the VoIP G / W 400 is connected to the G / W matching unit 222.

The CO line changer 200 performs a corresponding operation when a specific command (for example, transfer on / off, modem reset, and password change command) is applied from the outside. It connects to the trunk of the called party and sends outward through the VoIP trunk line, and in case of emergency, it connects the VoIP trunk line to the PSTN line and controls the incoming and outgoing calls. The specific command from the outside uses the DTMF signal input by the manager 700 through the assigned specific line. Detailed configuration and function of the CO line remote switching device 200 will be described later in detail with reference to FIG. 2.

The VoIP G / W 400 is connected to the G / W matching unit 222 of the CO line switch 200, and the VoIP G / W 400 is connected to the outside from the private switch 100. An apparatus for performing protocol matching, connected to a call counterpart via the Internet 500 to support a VoIP call. The VoIP G / W 400 is well known to those skilled in the art and thus will not be described in detail herein.

The internet modem 450 is located between the VoIP G / W 400 and the Internet 500, and modulates and demodulates the data to match the format of the data exchanged between the VoIP G / W 400 and the Internet 500. Play a role. That is, it modulates and transmits a digital signal into an analog signal, and demodulates the transmitted analog signal into an original digital signal.

The G / K (Gate Keeper) 600 is connected to the VoIP G / W 400, and periodically pings the VoIP G / W 400 so that the network connection state and abnormality of the VoIP G / W 400 are performed. It checks whether or not. The ping processing result is transmitted to the manager 700, and the manager 700 determines whether to switch according to the ping processing result and performs remote control of the CO line remote changer 200. Ping processing of the G / K 600 is performed using a simple network management protocol (SNMP), which is a simple network management protocol, and the ping may be performed to inspect and manage the current state of the VoIP G / W 400.

2 is a block diagram showing the internal configuration and connection relationship of the CO line remote changer 200 according to the present invention, the CO line remote changer 200 is composed of a telephone control unit 210 and a matching unit 220 for the transfer control. The switching means telephone means 210 includes a ring detector 211, a DTMF receiver 212, a controller 213, a hook on / off switch 214, a memory 215, a tone generator 216, A first relay driver 217 and a second relay driver 218 are included, and the matching unit 220 includes a C / O matching unit 221 and a G / W (GateWay) matching unit 222.

The ring detection unit 211 of the switching control telephone unit 210 detects the ring signal (75 Vrms, 20 Hz, 2 seconds per second) flowing through the PSTN 400 to generate a ring detection signal, and generates the generated ring detection. It serves to apply a signal to a designated path (eg, the controller 213). That is, the ring detector 211 outputs a low signal (ie, 0 V) when a ring signal is detected, and outputs a high signal (ie, 5 V) when a ring signal is not detected.

The DTMF receiver 212 receives a DTMF signal applied through the PSTN 400, reads a key signal inputted by an administrator (that is, a transfer authority), and then inputs a data signal corresponding to the key signal (for example, a password and a transfer control command). ) Is transmitted to the designated path (that is, the control unit 213). Here, the DTMF signal is a signal for distinguishing each key signal. DTMF signals consist of two different frequencies (ie high and low frequencies) that cannot be simulated by human voices.

The control unit 213 is connected to the ring detecting unit 211 and the DTMF receiving unit 212, and transmits a hook on / off switching signal by the ring detecting signal applied from the ring detecting unit 211, and from the DTMF receiving unit 212. Various control signals (e.g., relay drive signals) for receiving a data signal corresponding to an applied numeric key to instruct a switchover operation (e.g., transfer off, transfer on, modem reset operation) and password change operation corresponding to the data signal. , To generate a tone generation signal). For example, the administrator inputs the password to process the authentication process, and the transfer procedure and password change procedure corresponding to the designated number (eg, '1' is transferred off, '2' is switched on, and '3' is Modem reset, '4' means password change). Also, control to send a confirmation tone for notifying the administrator of the completion of the transfer on / off operation and the completion of the modem reset operation, a setting tone for notifying the administrator of the completion of the transfer confirmation operation, and an error tone for notifying whether or not an error has occurred. Then, the relay driving signal according to the switching on / off operation is sent to control to drive the relay. In addition, the controller 213 may add a function of receiving a DTMF signal input through the DTMF receiver 212 and analyzing a data signal corresponding to the input DTMF signal. That is, when the data signal analysis function is added to the control unit 213, the DTMF receiving unit 212 only plays a role of relaying the applied DTMF signal to the control unit 213.

The hook on / off switching unit 214 is connected to the control unit 213, and maintains the transfer control telephone means 210 in the available or standby state according to the hook on / off control signal transmitted from the control unit 213. It plays a role. Since the switching control telephone means 210 is automatically operated, it is necessary to automatically switch the available state or standby state according to whether the ring signal is detected. That is, the transfer control can be performed only when the transfer control phone means 210 is in the callable state (hook off state). On the contrary, after the transfer operation is completed, the transfer control unit 210 switches to the standby state (hook on state) to change over later. Allows you to perform an action.

The memory unit 215 is interconnected with the control unit 213, and stores a password for authenticating the switching operation and a program for performing the corresponding switching operation for each assigned number. That is, the memory unit 215 is programmed to perform the switching operation according to the data signal (that is, the data signal corresponding to the DTMF signal) applied from the control unit 213. For example, after password authentication, a switch-off operation is performed when '1' is input, a switch-on operation is performed when '2' is input, a modem reset operation is performed when '3' is input, and '4' is input. Is programmed to perform the password change operation.

The tone generating unit 216 is connected to the control unit 213 and transmits the corresponding tone to the PSTN according to the tone generating signal (ie, confirmation tone generating signal, setting tone generating signal, and error tone generating signal) applied from the control unit 213. It serves to send to the call request manager 700 through the 400. The tone generation signal is for notifying the administrator 700 of the completion of the transfer operation, the modem reset operation, and the password change operation. The tone generation signal is transmitted when the transfer on / off operation, the modem reset operation, and the password change operation are completed. After performing the proper authentication procedure, it sends out a setting tone to indicate the current status. Here, an error tone is sent when an illegal authentication procedure is performed. Accordingly, the manager can immediately know whether the transfer operation desired by the user and the current state of the CO line remote changer are performed by listening to the confirmation tone or the setting tone. Here, the confirmation tone, the setting tone and the error tone can be freely set, but the confirmation tone according to the embodiment of the present invention is set to transmit a DTMF signal corresponding to '1' for 1 second, and the setting tone is switched on ' The DTMF signal from 1 'to' 9 'is transmitted once at 0.2 second intervals, and when switching off, the DTMF signal corresponding to' 1 'is transmitted 3 times at 0.2 second intervals, and the error tone corresponds to' 1 '. Set to send the DTMF signal three times in one second.

The first relay driver 217 is connected to the control unit 213 and serves to drive each relay of the matching unit 220 by a relay driving signal applied from the control unit 213. The second relay driver 218 is connected to the control unit 213, and serves to reset the internet modem 450 by a relay driving signal applied from the control unit 213.

The C / O matching unit 221 of the matching unit 220 is connected to the first relay driving unit 217 of the switching control telephone unit 210, and connects the private exchange side trunk line to the PSTN 400, By assigning a trunk line serves to connect the trunk line to the switch control telephone means 210. The G / W matching unit 222 is connected to the first relay driving unit 217 of the switching control telephone means 210, connects the private exchange side VoIP line to the VoIP G / W 600, and relays at the transfer command. It acts to connect the private line VoIP line with the PSTN line. That is, in an incoming / outgoing call, when the transfer is off, the PSTN line is connected to the trunk line of the private exchange, and the incoming call is made. The private line of the VoIP line is connected to the VoIP G / W and the call is transferred. The VoIP side of the exchange is connected to the PSTN line to switch the incoming and outgoing calls.

In addition, the transfer control telephone means 210 may provide a service for providing a voice for the transfer control procedure by additionally configuring the voice guide unit in addition to the above-described components.

Hereinafter, on the basis of the accompanying drawings the operation relationship for the CO line remote switching device according to the present invention in more detail as follows.

3 is a flowchart illustrating a control operation of a trunk line remote changer according to the present invention. Prior to the description of the control operation of the CO line remote switching device, an arbitrary switching phone number is assigned to the transfer control telephone means, and the assigned private exchange side specific trunk line is connected to the transfer control telephone means, It is assumed that the memory unit stores a password for authenticating the transfer operation. In addition, the initial state of the trunk line remote changer is a switch-on state (a state in which a private exchange side trunk line and a private exchange side VoIP line are connected to a PSTN line), and when the power is applied, the transfer state is switched off (a private exchange side trunk line). Is connected to the PSTN line, and the private exchange side VoIP line is connected to the VoIP G / W).

First, the administrator determines the network connection status and abnormality of the VoIP G / W based on the result of the ping performed by G / K, and changes the remote operation (including transfer on, transfer off, modem reset operation) and password change at a remote place. If you want to perform the operation, try to connect the call by entering the transfer number assigned to the transfer control telephone means.

The control unit of the switching control telephone means determines whether a ring signal is detected through the ring detection unit (S305) and waits if no ring signal is detected, and sends a hook-off signal to the hook on / off switching unit when the ring signal is detected. At the same time, the phone unit is switched to the available state of call and the confirmation tone generation signal is applied to the tone generating unit to control the transmission of the confirmation tone (S310). When the administrator inputs the transfer telephone number, the ring signal is transmitted to the ring detection unit of the transfer control telephone means through the assigned trunk line of the private exchange, and the administrator transfers the transfer control phone depending on whether or not to transmit the confirmation tone from the transfer control telephone means. It is possible to recognize whether or not the means can be called. The confirmation tone according to the embodiment of the present invention is set to transmit a DTMF signal corresponding to '1' for 1 second.

The manager who has received the confirmation tone performs an authentication procedure to perform the transfer operation (S315). The transfer operation authentication procedure according to the embodiment of the present invention is set to press an authentication end key (eg, '*') after pressing an authentication (eg, '*') and a password. However, the transfer operation authentication procedure is not limited to the above-described method, of course, other authentication procedures can be used. The control unit analyzes the authentication procedure performed by the administrator to determine whether authentication is successful (S320). Authentication success is based on whether the password stored in the memory unit and the password entered by the administrator. Here, the authentication start, password, and authentication end key input by the administrator are analyzed through the DTMF receiving unit and applied to the control unit. The control unit reads whether the password matches based on the analyzed DTMF signal. If authentication is not performed, a password error has occurred, so all the switching operations are terminated, and the control unit transmits an error tone through the tone generating unit (S325), and then proceeds to an initial state. When the authentication is made, the control unit transmits a setting tone corresponding to the current transfer state of the CO line remote changer (S330). The transfer on set tone according to the embodiment of the present invention is set to transmit the DTMF signals '1' through '9' once at 0.2 second intervals, and the transfer off set tone transmits the DTMF signal corresponding to '1'. It is set to transmit three times at 0.2 second intervals. Therefore, the administrator can check the current transfer state of the CO line remote changer by listening to the setting tone.

Next, the administrator inputs a specific number for performing the desired switching operation and the password change operation (S335). For example, '1' may be assigned as a number for a switching off operation, '2' is a switching on operation, '3' is a modem reset operation, and '4' is a number for a password change operation.

When the administrator inputs a transfer off number (eg, '1'), the controller applies a relay driving signal to the first relay driver, and the first relay driver switches off the relays of the C / O matching unit and the G / W matching unit. Drive (S340). As described above, the switch-off state in the VoIP call is a state in which the private branch side trunk line is connected to the PSTN line and the private exchange side VoIP line is connected to the VoIP G / W.

When the administrator inputs a switch-on number (eg, '2'), the controller applies a relay driving signal to the first relay driver, and the first relay driver switches on the relays of the C / O matching unit and the G / W matching unit. Drive (S345). As described above, the switch-on state in the VoIP call is a state in which the private branch side trunk line and the private branch side VoIP line are connected to the PSTN line.

When the administrator inputs the modem reset number (eg, '3'), the controller applies a relay driving signal to the second relay driver, and the second relay driver turns the relay on and then off again to reset the power of the Internet modem. (S350). The reason for resetting the Internet modem is that even if the VoIP G / W operates normally, VoIP calls cannot be made due to the instability of the Internet modem. In this case, reset the Internet modem to allow normal operation.

When the administrator inputs a password change number (eg, '4'), the controller instructs to input a password to be changed, and the administrator inputs a password and a confirmation key (eg, '*') to be changed (S355). The control unit instructs the administrator to store the change password pressed by the manager (S360).

After the steps (S340, S345, 350, 360) in which the administrator has performed both the desired switching operation and the password changing operation, the controller sends a confirmation tone for notifying the administrator of the completion of the operation, and the on / off switching unit. By sending the hook-on signal and switching the transfer control telephone means to the hook-on state (that is, the call standby state) (S370), it is managed to perform a later transfer operation. The confirmation tone according to the embodiment of the present invention is set to transmit a DTMF signal corresponding to '1' for 1 second.

The above descriptions are merely illustrative of one embodiment, and the present invention is not limited to the above-described embodiments, and various modifications can be made within the appended utility model registration claims. For example, the shape and structure of each component specifically shown in the embodiment of the present invention may be modified.

As described above, according to the CO line remote changer according to the present invention, even when an VoIP call is not possible by controlling the CO line remote changer in a remote state in an emergency (for example, in case of VoIP gateway or Internet overload or other service failure). It has the effect of making a call (including call origination) through PSTN.

In addition, it is possible to immediately check the current state of the CO line remote changer at a remote site to select a possible call line to make a call, and select a desired call line to make a call.

Claims (4)

The PSTN line is connected to the trunk line of the private exchange side and the VoIP G / W and the Internet are connected to the VoIP line of the private exchange side so that an incoming call is made through the PSTN line, an outgoing call is made through the VoIP line, and the VoIP G / P / P which checks the network connection status and abnormality of the VoIP G / W and notifies the administrator of the test result and the VoIP G / W is located between the VoIP G / W and the Internet. A VoIP call system comprising an internet modem for modulating and demodulating data in order to match a format of data exchanged between the Internet and the Internet. Assigns an arbitrary switching phone number and communicates with the manager through a specific trunk line of the private exchange side, and connects the private exchange side trunk line to the PSTN line according to the transfer operation command of the administrator who performed the authentication procedure. A switch-off operation is performed by connecting a private exchange side VoIP line to the VoIP G / W, and performs a switch-on operation by connecting the private exchange side trunk line and the private exchange side VoIP line to the PSTN line and perform a current transfer. A switching control telephone means for performing a switching confirmation operation of identifying a status and notifying the administrator, and resetting the Internet modem according to the modem reset command of the administrator; And And a matching unit connected to the transfer control telephone means, the matching unit switching to a designated path according to a transfer operation command of the transfer control telephone means. The telephone switching means according to claim 1, wherein A ring detector for detecting a ring signal flowing through the PSTN; A DTMF receiver which receives a DTMF signal applied through the PSTN, reads an input key signal, and transmits a data signal corresponding to the key signal along a designated path; It is connected to the ring detector and the DTMF receiver, and transmits a hook on / off switch signal by a ring detection signal applied from the ring detector, and receives and authenticates a data signal corresponding to the key signal applied from the DTMF receiver. A control unit which controls to transmit various control signals instructing to perform a procedure, a changeover operation and a password change operation corresponding to the data signal; A hook on / off switching unit connected to the control unit, the hook on / off switching unit maintaining the callable state or the standby state according to the hook on / off control signal transmitted from the controller; A memory unit which is connected to the control unit and stores a program for performing a corresponding switching operation for each password and an allocation number for authenticating the switching operation; A tone generating unit connected to the control unit and transmitting a corresponding tone to the manager requesting a call through the PSTN according to a tone generation signal applied from the control unit; A first relay driver connected to the controller and driving the corresponding relay by a relay driving signal applied from the controller; And And a second relay driver connected to the controller, the second relay driver resetting the internet modem by a relay driving signal applied from the controller. The method of claim 1, wherein the matching portion A C / O matching unit connected to the transfer control telephone means, the trunk line connecting the private exchange side trunk line to the PSTN, and assigning a specific trunk line to connect the trunk line to the transfer control telephone means; And Connected to the transfer control telephone means and the C / O matching unit, and connects the private exchange side VoIP line to the VoIP G / W, and drives a relay according to a transfer operation command applied from the transfer control telephone means. And a G / W matching unit for connecting the private line side VoIP line with the PSTN line. The trunk line remote transfer device according to claim 2, wherein the transfer control telephone means further includes a voice guide unit for informing a procedure for transfer control by voice.