Telephone applicable to PSTN and IP network and call connection control method

Abstract

A telephone applicable to PSTN and IP network having functions of obtaining, when a call is originated by entering a PSTN telephone number, an IP network telephone number of a destination telephone corresponding to the PSTN telephone number from a telephone number translation server connected to the IP network, obtaining IP address information of the destination telephone corresponding to the IP network telephone number from a call agent connected to the IP network, establishing call connection with the destination telephone via the IP network by using the IP address information, and establishing call connection with the destination telephone via the PSTN if the IP network telephone number of the destination telephone cannot be obtained from the telephone number translation server.

1 . A telephone applicable to a public switched telephone network (PSTN) and an IP network, comprising: 
 a cache table for storing mappings between PSTN telephone numbers and IP network telephone numbers of telephones having been called before from the telephone;    means for searching said cache table, when a call is originated by entering a PSTN telephone number, for an IP network telephone number of a destination telephone corresponding to the entered PSTN telephone number, and, if the IP network telephone number of the destination telephone does not exist in the cache table, communicating with a telephone number translation server connected to the IP network and obtaining the IP network telephone number of the destination telephone corresponding to said PSTN telephone number;    means for obtaining IP address information of the destination telephone corresponding to the IP network telephone number obtained from said cache table or said telephone number translation server, from a call agent connected to the IP network and establishing call connection with the destination telephone via the IP network by using the IP address information; and    means for establishing call connection with the destination telephone via the PSTN if the IP network telephone number of the destination telephone cannot be obtained from said cache table and said telephone number translation server.    
     
     
         2 . The telephone according to  claim 1 , wherein said means for obtaining the IP network telephone number stores a mapping between the IP network telephone number of said destination telephone, obtained from said telephone number translation server, and said PSTN telephone number into said cache table.  
     
     
         3 . The telephone according to  claim 1 , further comprising means for communicating with said telephone number translation server and registering a mapping of the telephone's own PSTN telephone number and IP network telephone number to the server when the telephone is connected to the IP network.  
     
     
         4 . The telephone according to  claim 1 , wherein, if the entered PSTN telephone number consists entirely of local exchange code and subscriber number, said means for obtaining the IP network telephone number converts the entered PSTN telephone number into a numbering format including a toll number prior to obtaining the IP network telephone number of the destination telephone.  
     
     
         5 . A telephone applicable to a public switched telephone network (PSTN) and an IP network, comprising: 
 a cache table for storing mappings between PSTN telephone numbers and unification identifiers of telephones having been called before from the telephone;    means for searching said cache table, when a call is originated by entering a PSTN telephone number, for a unification identifier of a destination telephone corresponding to the entered PSTN telephone number, and, if the unification identifier of the destination telephone does not exist in the cache table, communicating with a telephone number translation server connected to the IP network and obtaining the unification identifier of the destination telephone corresponding to said PSTN telephone number;    means for requesting a call agent connected to said IP network to establish call connection with the destination telephone via the IP network, based on the unification identifier obtained from said cache table or said telephone number translation sever; and    means for establishing call connection with the destination telephone via the PSTN if the unification identifier of the destination telephone cannot be obtained from said cache table and said telephone number translation server.    
     
     
         6 . The telephone according to  claim 5 , wherein, if the entered PSTN telephone number consists entirely of local exchange code and subscriber number, said means for obtaining the IP network telephone number converts the entered PSTN telephone number into a numbering format including a toll number prior to obtaining the IP network telephone number of the destination telephone.