Patent Publication Number: US-2005143057-A1

Title: Method for forwarding call from cellular phone to IP phone

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application is based upon and claims a priority of Japanese Patent Application No. 2003-434932, filed on Dec. 26, 2003, the contents being incorporated herein by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a method for forwarding a call from a cellular phone to an IP phone in which a call from an IP phone to a cellular phone using a public network is forwarded to another IP phone, in a VoIP (Voice over Internet Protocol) network. The VoIP is known as a technology to convert speech to IP packets. Each packet constitute a unit of data.  
      2. Description of the Related Art  
      Recently, the broadbandization of access lines through xDSL, Cable Internet, an optical fiber, radio transmission or the like and the sophistication of network-related devices have been promoted, and the diffusion thereof has been also accelerated. Various applications and services are provided through an IP (Internet Protocol) network.  
      Particularly, an IP phone (Internet Protocol phone) service has been used to provide a phone-call speech service on the IP network using the VoIP technology to transmit speech using IP. The IP phone can be lower in cost, compared with an existing phone, and the IP phone will increasingly spread, in accordance with the development of the network technology, in the future.  
      With the future diffusion of the IP phone, it is expected that those who use both an IP phone service and a cellular phone service will be increased. For example, in a company, an in-house IP phone system covering all the offices will be built while the employees will carry cellular phones for personal contact and move between the offices and work therein.  
      However, the calling rate of a call between the IP phone and the cellular phone is higher than that between the cellular phones. As a prior art to solve this problem, there is a system disclosed in an international application PCT/JP02/08850 filed on Aug. 30, 2002 by the applicant of this application.  
       FIG. 1  is a schematic block diagram showing the structure of the prior art system.  
      In  FIG. 1 , numeral  10  represents a calling IP phone, numeral  20  represents a called cellular phone, numeral  30  represents a called IP phone, numeral  40  represents a speech control server, and numeral  45  represents an IP network.  
      The speech server  40  is called a call agent and functions as, for example, a software version of a switchboard in the company. The speech server  40  is provided with a phone connection information storage managing unit  41  and a communication controlling unit  42 .  
      The IP phone  30  is comprised of a connection controlling unit  31  which reads the phone number of a connected cellular phone and a phone connection information notifying unit  32  to notify the speech server  40  of phone connection information including the cellular phone number. The IP phone is known as a phone which is connected to the IP network and which is operated by software.  
      When the calling IP phone  10  makes a call to the cellular phone  20 , the speech control server  40  executes the switching function by the phone connection information storage managing unit  41  and the communication controlling unit  42  therein to send a call to the cellular phone via a public network (not shown). A holder of the cellular phone  20  makes a wire connection physically to an IP phone  30  nearby to save the call charge of the calling IP phone  10 . The IP phone  30  notifies the speech server  40  of the phone connection information including the phone number. Consequently, the speech server  40  connects the calling IP phone  10  and the called IP phone  30  via the IP network  45  so that the communication between the IP phones can be established.  
      [Patent Literature 1] Japanese Kokai No. 9-044396  
      [Patent Literature 2] Japanese Kokai No. 10-135968  
      [Patent Literature 3] Japanese Kokai No. 11-317072  
      [Patent Literature 4] Japanese Kokai No. 2002-199029  
      [Patent Literature 5] Specification of PCT/JP02/08850  
      [Invention Disclosure] 
      [Problems to be Solved by the Invention] 
      In the above prior art, if the call from the calling IP phone  10  to the called IP phone  20  is forwarded to the IP phone  30  during calling or speaking, the called cellular phone  20  must be physically connected to the to-be-forwarded IP phone  30  with a wire.  
      However, the holder of the called cellular phone  20  is not always near the IP phone  30  to which the incoming call is to be forwarded. If the called cellular phone  20  receives a phone call when its holder is far from the IP phone  30  to which the incoming cell is to be forwarded, no physical wire connection with the IP phone  30  to which the incoming call is to be forwarded is possible. Therefore, the speech has to be carried out between the calling IP phone  10  and the called cellular phone  20 , and high call fees would be charged to the calling IP phone  10 .  
     SUMMARY OF THE INVENTION  
      The present invention is aimed to solve the above problems in the prior art, by making it possible to connect the called cellular phone and the IP phone to which the incoming call is to be forwarded, at an application level, using wireless communication.  
      To achieve the above purpose, according to a first aspect of the present invention, there is provided a method for forwarding an incoming call from a cellular phone to an IP phone in a communication system in which speech communication is carried out on an Internet Protocol network, comprising 
          a first step in which, when a call arrives at a called cellular phone from a calling IP phone, a called person operates a called IP phone, to which the incoming call is to be forwarded, whereby a wireless communication is carried out between the called IP phone and the called cellular phone, and     a second step in which, after the first step, a function built into the called IP phone to which the incoming call is to be forwarded, automatically performs communication with the calling IP phone,     so that the incoming call to the called cellular phone is wirelessly forwarded to the called IP phone to be forwarded.        

      According to a second aspect of the present invention, there is provided 
          a method for switching a call from a cellular phone to an IP phone in a communication system in which a speech communication is carried out on an Internet Protocol network, comprising     a first step in which, when a call arrives at a called cellular phone from a calling IP phone, the called person operates a called IP phone, to which the incoming call is to be forwarded, whereby a wireless communication is carried out between the called IP phone and the called cellular phone,     a second step in which after the first step, a function built into the called IP phone, to which the incoming call is to be forwarded, automatically performs communication with the calling IP phone,     a third step in which the function built in the called IP phone which is communicating with the cellular phone interrupts the communication,     a fourth step in which the IP phone which has been communicating with the cellular phone makes a call to an IP phone, to which the incoming call is to be forwarded, whereby the speech communication is switched to the IP phone to be forwarded.        

      In the above first or second aspect of the invention, the communication system can be provided with a memory in which an identification number of the IP phone is registered, and a function built into the IP phone, to which the incoming call is to be forwarded, can automatically communicate with the memory and the IP phone in communication in the second step.  
      In the above first or second aspect of the invention, the communication system can be provided with a memory in which an identification number of the IP phone is registered, and the function built into the IP phone, to which the incoming call is to be forwarded, can automatically communicate with a switching device and the IP phone in communication in the second step.  
      In the above fourth step in the second aspect of the invention, when the call is switched from the cellular phone to the IP phone to which the incoming call is to be forwarded, the called person can recognize the switching of the call by a ringing tone of the IP phone to be forwarded.  
      In this invention, as it is not necessary for the IP phone and the cellular phone to be physically connected by a wire, it is advantageous that work for the physical connection between the IP phone and the cellular phone becomes unnecessary. It is also advantageous that it is not necessary to specify a particular IP phone, to which the incoming call is to be forwarded. Concretely, during calling from the IP phone to the cellular phone or during communication between the IP phone to the cellular phone, the nearest IP phone of the holder of the cellular phone is operated so as to provide a call forwarding method to forward the call or speech communication to the IP phone wirelessly. 
    
    
     BRIEF EXPLANATION OF DRAWINGS  
       FIG. 1  is a schematic block diagram showing a structure of a conventional system.  
       FIG. 2  is a schematic block diagram showing a structure of a communication system to carry out a method for forwarding an incoming call from a cellular phone to an IP phone according to an embodiment of the present invention.  
       FIG. 3  is a structural view showing an entire structure of a system of an embodiment in which the system shown in  FIG. 2  is applied to a headquarters and a branch office.  
       FIG. 4  shows an example of a content in a storage area of an address management server  2  in the branch office  301  in  FIG. 3 .  
       FIG. 5  shows caller&#39;s number registration data in the cellular phone  6 .  
       FIG. 6  is a part of a flow chart illustrating a process to switch and forward a call received by the cellular phone  6  to an IP phone, to which the incoming call is to be forwarded, according to an embodiment of the present invention.  
       FIG. 7  is another part of a flow chart illustrating a process to switch and forward a call received by the cellular phone  6  to an IP phone, to which the incoming call is to be forwarded, according to an embodiment of the present invention.  
       FIG. 8  is a part of a flow chart illustrating a method to forward a call from a cellular phone to an IP phone according to another embodiment of the present invention.  
       FIG. 9  is another part of a flow chart illustrating a method to forward a call from a cellular phone to an IP phone according to another embodiment of the present invention.  
       FIG. 10  is a structural view of data transmitted between a cellular phone and an IP phone.  
       FIG. 11  is a structural view of data to be searched in a storage area.  
       FIG. 12  is a structural view of data obtained from a storage area.  
       FIG. 13  is a structural view of broadcast data.  
       FIG. 14  shows a time sequence illustrating communication established between an IP phone and a cellular phone.  
       FIG. 15  shows a time sequence illustrating a data transmission between the cellular phone and the IP phone of  FIG. 7 .  
       FIG. 16  shows a time sequence illustrating a data transmission between an IP phone and an address management server.  
       FIG. 17  shows a time sequence illustrating speech communication established between an IP phone  1 - 1  and an IP phone  5 - 1 . 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION  
      The purpose to enable a connection between the called cellular phone and the forwarded IP phone in an application level wirelessly is realized by wirelessly transferring the incoming call designated to the called cellular phone to the called IP phone, to which the incoming call is to be forwarded, or by wireless communication between the called IP phone, to which the incoming call is to be forwarded, and the cellular phone by operating the called IP phone, to which the incoming call is to be forwarded, during the call between the IP phone and the cellular phone.  
     EMBODIMENT 1  
      Embodiment of the present invention will be explained below with reference to the drawings.  
       FIG. 2  is a schematic block diagram showing a structure of a communication system to realize a method for forwarding a call from a cellular phone to an IP phone according to an embodiment of the present invention. In  FIG. 2 , like reference numbers are assigned to components corresponding to those in  FIG. 1 . Numeral  10  represents the calling IP phone,  45  the IP network,  50  the called IP phone, and  60  the cellular phone. The called IP phone  50  is comprised of a wireless connection controlling unit  51  to carry out wireless communication with the called cellular phone  60  and a number reading managing unit  52  to read the phone number of the cellular phone. The cellular phone  60  is also comprised of a wireless connection controlling unit  61  to carry out wireless communication with the forwarded IP phone  50  and a number reading managing unit  62  to notify the phone number of the cellular phone.  
      According to the system shown in  FIG. 2 , the wireless connection interface between the forwarded IP phone  50  and the called cellular phone  60  is controlled by an application.  
       FIG. 3  shows the entire structure of the system of an embodiment applied to a headquarters and a branch office. Only the part essential for the explanation of the present invention is shown in the drawings.  
      In  FIG. 3 , in a telephone system of the embodiment, the headquarters  301  and the branch office  302  are connected via a public network  303  and an IP network  304 . In the headquarters  301 , there are provided IP phones  1 - 1 ,  1 - 2 , . . . , an address management server  2  which is a storage device to register identification numbers of the IP phones, and a router  4 - 1  to connect a private branch exchange IP-PBX  3 - 1  to the IP network  304 . In the branch office  302 , there are provided a private branch exchange IP-PBX  3 - 2 , a router  4 - 2  connected to the IP network  304 , and IP phones  5 - 1 ,  5 - 2 , . . . . The IP-PBX is required when a LAN is used as an internal phone network and is known as an exchanger directly linked to LAN having an exchange processing function embedded therein between the telephones and terminals. It is assumed that a holder who carries the cellular phone  6  is in the branch office  302 .  
      Speech communication between the headquarters  301  and the branch office  302  can be carried out via the in-house IP network  304  or the public network  303  with VoIP.  
      The cellular phone  6  in the branch office  302  can carry out speech communication through the public network  303  with the IP phones  1 - 1 ,  1 - 2 , . . . in the headquarters  301 . The cellular phone  6  can also carry out speech communication with the IP phones  5 - 2 , . . . in the branch office  302  and the other phones by wireless communication. The cellular phone  6  can further carry out data communication with the IP phones  1 - 1 ,  1 - 2 , . . . in the headquarters  301  by wireless communication.  
       FIG. 4  shows an example of a content in a storage area in the address management server  2  in the headquarters  301  in  FIG. 3 . It is assumed that in  FIG. 4 , caller&#39;s numbers of the extended IP phones  1 - 1 ,  1 - 2 , . . . in the headquarters  301  and the corresponding IP addresses in the IP network containing the extended IP phone numbers are registered in the storage area. The symbol * in  FIG. 4  represents a wild card representing an arbitrary value. For example, IP network addresses 10.1.1.1 and 10.1.1.2 corresponding to the caller&#39;s number 0987654321 in  FIG. 4  are for the IP phones  1 - 1  and  1 - 2 , respectively. However, the caller&#39;s number and the IP network address do not necessarily correspond to each other one-to-one. If the caller&#39;s number and the IP network address correspond to each other one-to-one, the address management server  2  is not necessary.  
      All of the extended IP phones  1 - 1 ,  1 - 2 , . . .  5 - 1 ,  5 - 2 , and the cellular phone  6  have special applications (indicated by symbol φ in  FIG. 3 ) having a function for wireless communication of the present invention.  
       FIG. 5  shows registered data of the caller&#39;s number in the cellular phone  6 .  
       FIG. 6  and  FIG. 7  are flow charts illustrating the processes to switch the call to the cellular phone  6  to an extended IP phone to which the incoming call is to be forwarded, during a call from the IP phone of the headquarters  301  or of the branch office  302  to the cellular phone  6 , according to the embodiment of the present invention.  
       FIG. 6  shows the operations to establish a speech communication between the extended IP phone  1 - 1  in the headquarters  301  and the extended IP phone  5 - 1  in the branch office  302 .  
      First, a caller in the headquarters  301  calls the cellular phone  6  in the branch office from the IP phone  1 - 1  in step S 60 . The cellular phone  6  refers to the data of  FIG. 5 . If the caller&#39;s number is registered, the communication state is started-up as a slave. It is assumed that the cellular phone  6  is not busy.  
      Next, when the cellular phone  6  is called in step S 61 , the caller&#39;s number is determined in step S 62 . If the caller&#39;s number is not registered in the cellular phone  6 , the cellular phone  6  answers the call or ignores the call in step S 63 .  
      If the caller&#39;s number is registered in the cellular phone  6 , the control proceeds to step S 64 . If the called person of the cellular phone  6  in the branch office  302  operates an extended IP phone to which the incoming call is to be forwarded, for example,  5 - 1 , whereby the cellular phone  6  can be in communication with the extended IP phone  5 - 1 . This process is shown in  FIG. 14 . Briefly, the IP communication state is set as a master by an application installed in the extended IP phone  5 - 1 , and communication with an application installed in the cellular phone  6  can be established due to Bluetooth communication. At this time, the IP phone  1 - 1  is still making a call to the cellular phone  6 .  
      In step S 65 , information is obtained from the application installed in the cellular phone  6  by the application installed in the IP phone  5 - 1  by wireless communication. An example of the data to be obtained is shown in  FIG. 10 . In  FIG. 10 , data to be transmitted and received between the cellular phone and the IP phone, for example, the caller&#39;s number (outside call number of the extended IP phone  1 - 11 ) and the phone number of the cellular phone, are shown.  
      In step S 66 , the application installed in the IP phone  5 - 1  searches the storage area of the address management server  2  in a method shown in  FIG. 16 , according to the data (the caller&#39;s number) obtained from the cellular phone  6  and obtains data shown in  FIG. 11  (a source network address). This data is a source network address corresponding to the caller&#39;s number (a network address of an IP network containing the IP phone  1 - 1 ).  
      According to another embodiment of the present invention, the caller&#39;s numbers of the extended phones and the corresponding IP addresses of the IP network including them are registered to obtain the source IP network address from the information, without providing the address management server  2  in the headquarters  301 .  
       FIG. 11  shows a data structure used for the inquiry, and  FIG. 12  shows a data structure obtained by the inquiry.  
      In step S 67  following step S 66 , it is determined whether the extended IP phone  5 - 1 ,  5 - 2 , . . . in the branch office  302  have obtained the IP network addresses. If obtained, the application installed in the IP phone  5 - 1  notifies the data shown in  FIG. 13  (the IP addresses of the cellular phone and the IP Phone  5 - 1  to be forwarded) to all the IP phones in the network including the IP phone  1 - 1 ,  1 - 2 , . . . , based on the source network address obtained in the step S 66  by broadcasting in step S 68 , thereby to inquire the calling IP phone. Broadcasting is known as a technology to send data to all the nodes in a particular scope of the network.  
      In step S 69 , if it is determined that the extended IP phone  1 - 1  is calling as a result of the inquiry, the control proceeds to step S 70 .  
      In the step S 70 , the application installed in the calling IP phone  1 - 1  notified in the step S 68  stops calling to the cellular phone  6  in a method shown in  FIG. 17 .  
      In step S 71 , the IP phone  1 - 1  in the headquarters  301  requests a connection (makes a call) based on SIP (Session Initiation Protocol) to the IP address of the IP phone  50  in the branch office. SIP is known as a text-base protocol on an application layer to realize a call setting of the phone.  
      In step S 72 , the incoming call from the IP phone  1 - 1  to the cellular phone is stopped and the call arrives the extended IP phone  5 - 1 .  
      In step S 73 , the call receiver of the cellular phone  6  in the branch office  302  operates the extended IP phone  5 - 1  thereby to start the speech connection between the extended IP phone  5 - 1  and the extended IP phone  1 - 1 .  
      According to the above process, it is possible to forward an incoming call from the extended phone to the cellular phone to the extended phone nearest thereto.  
      For the wireless communication between the extended IP phone and the cellular phone, a simple wireless communication means such as Bluetooth, or infrared communication, can be used. Bluetooth is known as an interface standard of a short-range wireless communication.  
     EMBODIMENT 2  
       FIG. 8  and  FIG. 9  are flow charts illustrating a method for switching and transferring a speech communication from a cellular phone to an extended IP phone according to another embodiment of the present invention.  
      If the cellular phone  6  is being in speech communication with the extended IP phone  1 - 1  in step S 80 , the cellular phone is set-up and in standby mode in a slave state as shown in  FIG. 14  with Bluetooth.  
      A speaker of the cellular phone  6  in the branch office  302  operates the nearest extended IP phone  5 - 1  to be forwarded. According to the method shown in  FIG. 14 , the application installed in the extended IP phone  5 - 1  sets the communication status due to Bluetooth as a master to be able to communicate with the application installed in the cellular phone  6  due to Bluetooth communication. At this time, the connection between the cellular phone  6  and the IP phone  1 - 1  is reserved.  
      The application installed in the extended IP phone  5 - 1  obtains data (caller&#39;s number (outside phone number of the IP phone  1 - 1 ) and the phone number of the cellular phone  6 ) shown in  FIG. 10  from the application installed in the cellular phone  6  by air according to the method shown in  FIG. 15 .  
      After obtaining the data, the control proceeds to step S 83 , in which the application installed in the extended IP phone  5 - 1  searches the address management server  2  by means shown in  FIG. 16  according to the data (the caller&#39;s number) shown in  FIG. 11  to obtain the data (the source network address) shown in  FIG. 12 , and to obtain the source network address (the network address of the network containing the IP phone  1 - 1 ) corresponding to the obtained caller&#39;s number.  
      In place of the address management server  2 , it is possible to register, in advance, the caller&#39;s number and the corresponding IP address of the network including the caller&#39;s number of the extended IP phone in an internal area of the IP-PBX  3 - 1 , so that the source network address can be obtained based on the information.  
      In step S 85 , the application installed in the IP phone  5 - 1  notifies the data (the phone number of the cellular phone and the IP address of forwarded IP phone  5 - 1 ) as shown in  FIG. 13  to all the IP phones  1 - 1 ,  1 - 2 , . . . in the IP network  340  containing the IP phone  1 - 1  based on the source network address determined in the step S 84  by broadcasting.  
      In step S 86 , if the IP phone  1 - 1  in speech communication obtains the above data, the flow goes to step S 90 . The application installed in the extended IP phone  1 - 1  breaks the speech communication with the cellular phone  6  by means shown in  FIG. 17 , and sends a connection request by SIP to the extended IP phone  5 - 1  in step S 91 .  
      In step S 92 , the IP phone  5 - 1  is called. The ring tone of the IP phone  5 - 1  is set different from that of the normal call, so that the call receiver can easily determine the switching of the call.  
      In step S 93 , the speaker of the cellular phone  6  in the branch office  302  operates the extended IP phone  5 - 1 , so that the IP phone  5 - 1  and the IP phone  1 - 1  can start the speech communication.  
      According to the above process, the speech communication between an extended phone and a cellular phone can be forwarded to the extended phone close thereto.  
      [Industrial Applicability] 
      (1) Cost  
      According to the present invention, a call rate, which is the most expensive and is applied a call from a general subscriber phone to a cellular phone, is unnecessary, thus resulting in remarkably reducing the call fee.  
      (2) Applications  
      According to the present invention, the calling person can use an extended phone if he/she knows only a cellular phone number, without knowing the extended number, of the called person.  
      Moreover, the called person can establish a speech communication in real time by operating the extended phone, to which the incoming call is to be forwarded, without physically connecting the cellular phone and the extended phone and registering information in a call control server.  
      Furthermore, according to the present invention, a calling person can use an extended phone system even if a called person is away from his/her desk (the called person is away from the extended phone whose information is registered in the call control server).  
      Furthermore, according to the present invention, an extended phone can be used if a calling person knows the cellular phone number in case that the extended phone number is changed due to seat change.