Patent Publication Number: US-2006007912-A1

Title: Ip-based pbx system and connecting method thereof

Description:
BACKGROUND OF INVENTION  
      1. Field of the Invention  
      The present invention relates to an IP-based PBX system and a connecting method thereof, and more particularly, to an IP-based PBX system having a host with a plurality of Internet connections to serve IP-based PBX extensions and a connecting method thereof.  
      2. Description of the Prior Art  
      With the popularity of Internet connections, many IP-based applications are developed to provide users Internet connections anytime and anywhere. For example, Voice over Internet Protocol (VoIP) systems are developed to transmit voice efficiently over the Internet. Concerning a prior art VoIP system, a VoIP host only has an Internet connection to connect the Internet for serving a plurality of VoIP terminals through the Internet. If the Internet connection is broken, network packets can be transmitted neither from the VoIP host to VoIP terminals nor from VoIP terminals to the VoIP host. In other words, the whole VoIP system fails to work normally.  
     SUMMARY OF INVENTION  
      It is therefore a primary objective of the claimed invention to provide an IP-based PBX system having a host with a plurality of Internet connections and a connecting method thereof to solve the above-mentioned problem.  
      According to the claimed invention, an IP-based PBX system is disclosed. The IP-based PBX system comprises an IP-based PBX host and at least an IP-based PBX extension. The IP-based PBX host is used for serving IP-based PBX extensions, and comprises a routing module for connecting the IP-based PBX host to the Internet through a plurality of Internet connections with a plurality of corresponding IP addresses. Each IP-based PBX extension selects a first IP address from the IP addresses for connecting the IP-based PBX host, and comprises a storage unit for recording the IP addresses.  
      In addition, the claimed invention provides a method of connecting an IP-based PBX host and at least an IP-based PBX extension. The IP-based PBX host is capable of serving the IP-based PBX extension through the Internet. The method comprises connecting the IP-based PBX host to the Internet through a plurality of Internet connections with a plurality of corresponding IP addresses, recording the IP addresses in the IP-based PBX extension, and utilizing the IP-based PBX extension to select a first IP address from the IP addresses for connecting the IP-based PBX host.  
      It is an advantage of the claimed invention that the IP-based PBX system and the related connecting method provide a IP-based PBX host with a plurality of Internet connections having a plurality of IP addresses respectively for serving IP-based PBX extensions. When one of the Internet connections is broken, the IP-based PBX extensions can communicate with the IP-based host through other Internet connections. Thus, the whole IP-based PBX system operates normally even though one of the Internet connections is broken.  
      These and other objectives of the claimed invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       FIG. 1  is a block diagram of an IP-based PBX system according to the present invention.  
       FIG. 2  is a flow chart illustrating operation of the IP-based PBX system shown in  FIG. 1 . 
    
    
     DETAILED DESCRIPTION  
      Please refer to  FIG. 1 .  FIG. 1  is a block diagram of an IP-based PBX system  10  according to the present invention. The IP-based PBX system  10  comprises an IP-based PBX host  12  for arbitrating data (e.g. voice packets) transmitted among a plurality of IP-based PBX extensions  22 ,  32  through the Internet  20 . The IP-based PBX host  12  comprises a routing module  14  for connecting the IP-based PBX host  12  to the Internet  20  through a plurality of Internet connections  16   a ,  16   b ,  16   c , and  16   d . The Internet connections  16   a ,  16   b ,  16   c , and  16   d  correspond to a plurality of IP addresses. The IP-based PBX extensions  22  are connected to an IP sharing device  24 , which is connected to the Internet  20  through an Internet connection  26 . The IP-based PBX extensions  32  are wirelessly connected to an IP sharing device  34  through an access point (AP)  30 . The IP sharing device  34  is further connected to the Internet  20  through an Internet connection  36 . In the preferred embodiment, the Internet connections  26  and  36  can be well-known xDSL modems, cable modems, T1 connections, or other broadband connections. In addition, each of the IP-based PBX extensions  22  has a storage unit  23 , and each of the IP-based PBX extensions  32  has a storage unit  33 .  
      Please refer to  FIG. 2 .  FIG. 2  is a flow chart illustrating operation of the IP-based PBX system  10  shown in  FIG. 1 . The operation includes following steps:  
      Step  100 : Power on an IP-based PBX extension;  
      Step  102 : The IP-based PBX extension selects an initial IP address for connecting the IP-based PBX host;  
      Step  104 : The IP-based PBX extension checks if the IP-based PBX host  12  is reachable through an initial Internet connection having the initial IP address. If the IP-based PBX extension successfully contacts the IP-based PBX host  12  by the initial Internet connection, go to step  108 ; otherwise, go to step  106 ;  
      Step  106 : The IP-based PBX extension checks if the IP-based PBX extension is capable of connecting the IP-based PBX host  12  through another Internet connection having a specific IP address. If the IP-based PBX extension successfully contacts the IP-based PBX host  12  by the selected Internet connection, go to step  108 ; otherwise, go to step  106 ;  
      Step  108 : The IP-based PBX extension is connected to the IP-based PBX host  12  and transmits VoIP packets to the IP-based PBX host  12  through the usable Internet connection; and  
      Step  110 : The IP-based PBX extension periodically checks if the currently adopted Internet connection is still available to the IP-based PBX extension. If the currently adopted Internet connection works normally, go to step  110 ; otherwise, go to step  106 .  
      In the preferred embodiment, each of the storage units  23 ,  33  is used for recording the IP addresses IPa, IPb, IPc, IPd of the corresponding Internet connections  16   a ,  16   b ,  16   c , and  16   d  utilized by the IP-based PBX host  12 . When one IP-based PBX extension  22 ,  32  is powered on (step  100 ), the IP-based PBX extension  22 ,  32  selects an initial IP address of these IP addresses stored in the storage unit for connecting the IP-based PBX host (step  102 ). For instance, when an IP-based PBX extension  22  connected to the IP sharing device  24  is turned on, the IP-based PBX extension  22  first searches its storage unit  23  for the IP address IPa of the Internet connection  16   a.  Then, the activated IP-based PBX extension  22  tries to contact the IP-based PBX host  12  via the selected IP address IPa. That is, the IP-based PBX extension  22  checks if it can contact the IP-based PBX host  12  through the Internet connection  16   a  having the selected IP address IPa (step  104 ). If the IP-based PBX extension  22  outputs packets to the IP-based PBX host  12  through the first Internet connection  16   a , and the IP-based PBX extension  22  does not receive any reply packet returned by the IP-based PBX host  12  for completing the well-known hand-shaking process, the IP-based PBX extension  22  deems that the IP-based PBX host  12  is not reachable through the selected IP address IPa. The IP-based PBX extension  22 , therefore, will select another IP address from remaining available IP addresses IPb, IPc, IPd to connect the IP-based PBX host  12  (step  106 ). For example, the IP address IPb corresponding to the Internet connection  16   b  is selected. Similarly, the IP-based PBX extension  22  checks if it can contact the IP-based PBX host  12  through the Internet connection  16   b  having the selected IP address IPb. However, if the hand-shaking process still fails, the IP-based PBX extension  22 , therefore, will select one IP address from other available IP addresses IPc, IPd to connect the IP-based PBX host  12  (step  106 ).  
      When the IP-based PBX extension  22  successfully contacts the IP-based PBX host  12  through one selected IP address IPa, IPb, IPc, or IPd (steps  104  and  106 ), the IP-based PBX extension  22  transmits VoIP packets to the IP-based PBX host  12  through the corresponding usable Internet connection  16   a ,  16   b ,  16   c , or  16   d  (step  108 ). In other words, the IP-based PBX extension  22  is correctly connected to the IP-based PBX host  12 , and the packet transaction between the IP-based PBX extension  22  and the IP-based PBX host  12  is activated.  
      Suppose that the IP-based PBX extension  22  is connected to the IP-based PBX host  12  through the Internet connection  16   a  (steps  104  and  108 ). However, the current network connection between the IP-based PBX extension  22  and IP-based PBX host  12  might be broken owing to malfunction of the Internet connection  16   a . Therefore, the IP-based PBX extension  22  periodically checks if the currently adopted Internet connection  16   a  is still available (step  110 ). If the current Internet connection  16   a  that the IP-based extension  22  is connected to does not work normally, the IP-based extension  22  immediately selects other available IP addresses IPb, IPc, and IPd recorded in the storage unit  23  to connect the IP-based PBX host  12  (step  106 ).  
      For the IP-based PBX host  12 , the IP-based PBX host  12  is capable of receiving packets outputted from the IP-based PBX extensions  22 ,  32  through all of the Internet connections  16   a ,  16   b ,  16   c , and  16   d . If the IP-based PBX host  12  detects that the Internet connection  16   d  is unable to receive packets for a predetermined period of time, the IP-based PBX host  12 , in the preferred embodiment, deems that the network connection built through the Internet connection  16   d  is broken. Therefore, IP-based PBX host  12  automatically transmits a notification packet to each IP-based PBX extension  22 ,  32  through other working Internet connections  16   a ,  16   b , and  16   c . The notification packet is used to notify each IP-based PBX extension  22 ,  32  about the unavailable Internet connection  16   d . As each IP-based PBX extension  22 ,  32  receives the notification packet, each of the IP-based PBX extensions  22 ,  32  removes the IP address IPd from the storage unit or stops utilizing the IP address IPd corresponding to the Internet connection  16   d  for outputting packets to the IP-based PBX host  12 . Each of the IP-based PBX extensions  22 ,  32  updates the available IP addresses according to the connecting conditions of the Internet connections  16   a ,  16   b ,  16   c , and  16   d . When one of the Internet connections  16   a ,  16   b ,  16   c , and  16   d  is broken, the IP-based PBX extensions  22 ,  32  are notified by the IP-based PBX host  12 . With the help of the notification packet provided by the IP-based PBX host  12 , the IP-based PBX extensions  22 ,  32  can efficiently establish required network connections through the Internet connections  16   a ,  16   b ,  16   c , and  16   d.    
      In contrast to the prior art, the IP-based PBX system and a related connecting method according to the present invention provide an IP-based PBX host with a plurality of Internet connections having a plurality of corresponding IP addresses to serve IP-based PBX extensions. When one of the Internet connections is broken, the IP-based PBX extensions can communicate with the IP-based host through other working Internet connections. Thus, the whole IP-based PBX system operates normally even though one of the Internet connections is broken.  
      Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention. Accordingly, that above disclosure should be construed as limited only by the metes and bounds of the appended claims.