Abstract:
The present invention provides a technique for directly calling telephones via a shared telephone number, which telephones do not have telephone numbers in the address space of the Public Switched Telephone Network. This is particularly useful for visitors and guests who are, for example, temporarily at a hotel, school campus, or business.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of:
         (1) U.S. Patent Application Ser. No. 60/600,809, filed Aug. 12, 2004, and   (2) U.S. Patent Application Ser. No. 60/634,119, filed Dec. 8, 2004,
 
which are both also incorporated by reference:
       

     U.S. patent application Ser. No. 11/203,356, filed Aug. 12, 2005, entitled “Complementary VoIP Service,” is also incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to telecommunications in general, and, more particularly, to the direct calling of devices accessible via a shared telephone number. 
     BACKGROUND OF THE INVENTION 
     Many telephones can be directly called because they have a unique telephone number associated with them. This telephone number is an address in the address space of the Public Switched Telephone Network. Many telephones cannot be directly addressed because they are accessible only via a private branch exchange. To call these telephones, you must first call the number for the private branch exchange and then a human operator or interactive voice response system asks for an extension. 
     The need exists therefore for a technique that enables the direct calling of telephones behind a private branch exchange. 
     SUMMARY OF THE INVENTION 
     The present invention provides a technique for directly calling telephones via a shared telephone number, which telephones do not have telephone numbers in the address space of the Public Switched Telephone Network. This is particularly useful for visitors and guests who are, for example, temporarily at a hotel, school campus, or business. 
     An example in the context of a guest at a hotel will illustrate the features of the illustrative embodiment. When a guest of the hotel desires to receive calls to his or her home telephone at the hotel, he or she directs the telephone company to forward calls to his or her home telephone to the hotel. In the prior art, such calls would be answered by the hotel&#39;s switchboard operator or interactive voice-response system and the caller would be asked how to direct the call. In some cases, this is disadvantageous because it alerts the caller that the guest is not at home. It is also disadvantageous because it requires the intervention of the hotel&#39;s operator. 
     In accordance with the illustrative embodiment, when the guest first registers at the hotel, the guest tells the desk clerk the telephone number of the guest&#39;s home telephone and the desk clerk enters the number and the extension of the telephone in the guest&#39;s room into the hotel&#39;s telephone switch and directs the switch to directly forward calls originally directed to the guest&#39;s home number to the telephone in the guest&#39;s room. 
     Thereafter, when a call to the guest&#39;s home number is forwarded to the hotel, the hotel switch will receive a set-up message from the Public Switched Telephone Network, which set-up message includes the originally-called telephone number (i.e., the guest&#39;s home telephone number). The hotel&#39;s telephone switch recognizes that the incoming call has been forwarded and extracts the originally-called telephone number from the set-up message. The switch then uses that number to find the hotel extension associated with that number. When it does, it automatically forwards that number to the guest&#39;s room without intervention by the hotel&#39;s switchboard operator or interactive voice-response system. This saves hotel resources and retains the guest&#39;s privacy. 
     Other embodiments of the present invention provide similar services in similar and different contexts. 
     The illustrative embodiment comprises: receiving a first call set-up message for a first voice telephone call that has been forwarded from a first originally-called telephone number, wherein the first originally-called telephone number is an address in the address space of the Public Switched Telephone Network; and attempting to establish a voice telephone call with a first device that has an address outside the address space of the Public Switched Telephone Network; wherein the address of the first device is found from the first originally-called telephone number. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts a schematic diagram of the salient components of a telecommunications system in accordance with the illustrative embodiment of the present invention. 
         FIG. 2  depicts a flowchart of the salient tasks associated with the operation of the illustrative embodiment. 
         FIG. 3  depicts a flowchart of the salient tasks associated with the operation of task  201 . 
         FIG. 4  depicts a flowchart of the salient tasks associated with the operation of task  202 . 
         FIG. 5  depicts a flowchart of the salient tasks associated with the operation of task  203 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  depicts a schematic diagram of the salient components of a telecommunications system in accordance with the illustrative embodiment of the present invention. System  100  comprises: telephones  101  through  105 , telephones  111  through  113 , switching network  121 , switch  122 , and forwarding database  123 , interrelated as shown. 
     Telephones  101  through  105  and switching network  121  reside in the domain of the Public Switched Telephone Network, and telephones  111  through  113 , and forwarding database  123  reside outside the domain of the Public Switched Telephone Network. Switch  122  resides in both domains and functions as the bridge between them. It will be clear to those skilled in the art, however, after reading this disclosure, how to make and use alternative embodiments of the present invention in which all of telephones  101  through  105 , telephones  111  through  113 , switching network  121 , switch  122 , and forwarding database  123  reside within the domain of the Public Switched Telephone Network. 
     Telephones  101  through  105  and telephones  111  through  113  are well known in the prior art and are devices that can function as telephones in that they can convert acoustic signals to electrical signals and electrical signals to acoustic signals, telephones  101  through  105  and Telephones  111  through  113  can be special-purpose devices (e.g., a telephone, etc.) that are used only for telephony or general-purpose devices (e.g., a computer, etc.) that can be used for both telephony and non-telephony both. 
     Each of telephones  101  through  105  and  111  through  113  can be wireline (e.g., Tip-Ring, ISDN, etc.) or wireless (e.g., cordless, cellular, etc.) devices. Each of telephones  101  through  105  is uniquely associated with a unique address (i.e., telephone number) in the address space of the Public Switched Telephone Network. In contrast, each of telephones  111  through  113  is uniquely associated with an extension in the address space of switch  122 . In accordance with the illustrative embodiment, telephone  103  is a business telephone, telephone  104  is a residential telephone, and telephone  105  is a dual-use residential and business telephone. It will be clear to those skilled in the art how to make and use telephones  101  through  105  and telephones  111  through  113 . 
     Switching network  121  is well known in the prior art and comprises the hardware and software necessary to receive a telephone call from telephone  101  that is directed to telephone  103  but that is forwarded to switch  122  conditionally or unconditionally. It will be clear to those skilled in the art how to make and use switching network  121 . 
     Switch  122  comprises the hardware and software necessary to perform the functionality described below and with respect to  FIGS. 2 through 5 . In some embodiments of the present invention, switch  122  is a private branch exchange that serves a hotel, school campus, or business. In some other embodiments, switch  122  is a central office switch owned by a telecommunications service provider that provides service (e.g., Centrex service, etc.) to a hotel, school campus, or business. 
     Forwarding database  123  is a database that correlates the telephone numbers (i.e., addresses in the address space of the Public Switched Telephone Network) of telephones  101  through  105  with extensions in the address space of switch  122 . A portion of forwarding database  123  is depicted in Table 1. 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Forwarding database 123 
               
             
          
           
               
                 Telephone 
                 PSTN Telephone Number 
                 Corresponding extension 
               
               
                   
               
               
                 103 
                 648-555-2443 
                 111 
               
               
                 104 
                 723-753-6642 
                 111 
               
               
                   
                 . . . 
                 . . . 
               
               
                 105 
                 945-843-6321 
                 112 
               
               
                   
               
             
          
         
       
     
       FIG. 2  depicts a flowchart of the salient tasks associated with the operation of the illustrative embodiment. The flowchart depicts the processing of three telephone calls: In accordance with the first, a first voice call to a first telephone number is forwarded to an extension behind switch  122 . In accordance with the second, a second voice call to a second telephone number is forwarded to the same extension behind switch  122 . The combination of the first call and the second call demonstrate that the illustrative embodiment can properly forward calls to different numbers to the same extension. 
     In accordance with the third call, a third voice call to a third telephone number is forwarded to a second extension. The combination of the first call and the third call demonstrates that the illustrative embodiment can properly forward calls to different numbers to different extensions behind switch  122 . 
     Prior to the execution of the tasks in  FIG. 2 , the user of telephone  103  has mapped the telephone number of telephone  103  (i.e., 648-555-2443) to the telephone number of telephone  111  (i.e., extension  111 ) and has directed switching network  121  to forward calls to the telephone number for telephone  103  to be forwarded to switch  122 . Similarly, the user of telephone  104  has mapped the telephone number of telephone  104  (i.e., 723-753-6642) to the telephone number of telephone  111  (i.e., extension  111 ) and has directed switching network  121  to forward calls to the telephone number for telephone  104  to be forwarded to switch  122 . And again similarly, the user of telephone  105  has mapped the telephone number of telephone  105  (i.e., 945-843-6321) to the telephone number of telephone  112  (i.e., extension  112 ) and has directed switching network  121  to forward calls to the telephone number for telephone  105  to be forwarded to switch  122 . 
     At task  201 , the illustrative embodiment forwards a first voice call that is originally placed to telephone  103  to extension  111 . 
     At task  202 , the illustrative embodiment forwards a second voice call that is originally placed to telephone  104  to extension  111 . 
     At task  203 , the illustrative embodiment forwards a third voice call that is originally placed to telephone  105  to extension  112 . 
       FIG. 3  depicts a flowchart of the salient tasks associated with the operation of the illustrative embodiment. 
     At subtask  301 , a voice call is initiated in well-known fashion, from telephone  101  to telephone  103  by dialing the PSTN telephone number 648-555-2443. 
     At subtask  302 , switching network  121  attempts to set up the call with telephone  103  in well-known fashion. 
     At subtask  303 , switching network  121  is unable to set up the call with telephone  103 , and, therefore, forwards the call to switch  122 . This could be because there was no one available to answer telephone  103 , or because all calls to telephone  103  were conditionally or unconditionally forwarded to switch  122 . When a call to telephone  103  is forwarded to switch  122 , switching network  121  transmits, as part of subtask  303 , a set-up message (e.g., an SS7 ISUP set-up message, etc.) to switch  122 , which message contains the originally-called telephone number (i.e., 648-555-2443—the telephone number of telephone  103 ). 
     At subtask  304 , switch  122  receives the set-up message and by examining it in well-known fashion, knows that the call has been forwarded to it. Because the call was forwarded to it, switch  122  extracts the originally-called telephone number from the set-up message and begins the process of establishing the call to the extension associated with the originally-called telephone number (i.e., the telephone number of telephone  111 ). 
     At subtask  305 , switch  122  transmits the originally-called telephone number (i.e., 648-555-2443) to forwarding database  123 . 
     At subtask  306 , forwarding database  123  finds the extension (i.e., extension  111 ) that corresponds to the originally-called telephone number and transmits the found extension back to switch  122 . 
     At subtask  307 , switch  122  receives the extension (i.e., extension  111 ) from forwarding database  123 . 
     At subtask  308 , switch  122  attempts, in well-known fashion, to establish the voice call with extension  111 . 
       FIG. 4  depicts a flowchart of the salient tasks associated with the operation of task  202 . 
     At subtask  401 , a voice call is initiated in well-known fashion, from telephone  102  to telephone  104  by dialing the PSTN telephone number 723-753-6642. 
     At subtask  402 , switching network  121  attempts to set up the call with telephone  104  in well-known fashion. 
     At subtask  403 , switching network  121  is unable to set up the call with telephone  104 , and, therefore, forwards the call to switch  122 . This could be because there was no one available to answer telephone  104 , or because all calls to telephone  104  were conditionally or unconditionally forwarded to switch  122 . When a call to telephone  104  is forwarded to switch  122 , switching network  121  transmits, as part of subtask  403 , a set-up message (e.g., an SS7 ISUP set-up message, etc.) to switch  122 , which message contains the originally-called telephone number (i.e., 723-753-6642—the telephone number of telephone  104 ). 
     At subtask  404 , switch  122  receives the set-up message and by examining it in well-known fashion, knows that the call has been forwarded to it. Because the call was forwarded to it, switch  122  extracts the originally-called telephone number from the set-up message and begins the process of establishing the call to the extension associated with the originally-called telephone number (i.e., the telephone number of telephone  111 ). 
     At subtask  405 , switch  122  transmits the originally-called telephone number (i.e., 723-753-6642) to forwarding database  123 . 
     At subtask  406 , forwarding database  123  finds the extension (i.e., extension  111 ) that corresponds to the originally-called telephone number and transmits the found extension back to switch  122 . 
     At subtask  407 , switch  122  receives the extension (i.e., extension  111 ) from forwarding database  123 . 
     At subtask  408 , switch  122  attempts, in well-known fashion, to establish the voice call with extension  111 . 
       FIG. 5  depicts a flowchart of the salient tasks associated with the operation of task  203 . 
     At subtask  501 , a voice call is initiated in well-known fashion, from telephone  101  to telephone  105  by dialing the PSTN telephone number 723-753-6642. 
     At subtask  502 , switching network  121  attempts to set up the call with telephone  105  in well-known fashion. 
     At subtask  503 , switching network  121  is unable to set up the call with telephone  105 , and, therefore, forwards the call to switch  122 . This could be because there was no one available to answer telephone  105 , or because all calls to telephone  105  were conditionally or unconditionally forwarded to switch  122 . When a call to telephone  105  is forwarded to switch  122 , switching network  121  transmits, as part of subtask  503 , a set-up message (e.g., an SS7 ISUP set-up message, etc.) to switch  122 , which message contains the originally-called telephone number (i.e., 723-753-6642—the telephone number of telephone  105 ). 
     At subtask  504 , switch  122  receives the set-up message and by examining it in well-known fashion, knows that the call has been forwarded to it. Because the call was forwarded to it, switch  122  extracts the originally-called telephone number from the set-up message and begins the process of establishing the call to the extension associated with the originally-called telephone number (i.e., the telephone number of telephone  112 ). 
     At subtask  505 , switch  122  transmits the originally-called telephone number (i.e., 723-753-6642) to forwarding database  123 . 
     At subtask  506 , forwarding database  123  finds the extension (i.e., extension  112 ) that corresponds to the originally-called telephone number and transmits the found extension back to switch  122 . 
     At subtask  507 , switch  122  receives the extension (i.e., extension  112 ) from forwarding database  123 . 
     At subtask  508 , switch  122  attempts, in well-known fashion, to establish the voice call with extension  112 . 
     It is to be understood that the above-described embodiments are merely illustrative of the present invention and that many variations of the above-described embodiments can be devised by those skilled in the art without departing from the scope of the invention. It is therefore intended that such variations be included within the scope of the following claims and their equivalents.