Abstract:
Utilizing an invisible agent within a remote switch to allow the redirection of calls received from a telephone set connected to a public telephone network to a main switching system.

Description:
TECHNICAL FIELD  
         [0001]    This invention relates to telecommunication switching, and in particular, to the redirection of calls from a first switch to a second switching system.  
         BACKGROUND OF THE INVENTION  
         [0002]    It is known in the prior art that as organizations grow geographically through mergers, acquisitions, or other means, it is desirable for a telecommunication system to operate as a single, geographically dispersed switching system with full feature transparency. It is known for a single telecommunication switching system to extend switching and control fabric of a single telecommunication system over a wide area using wide area networks (WAN) such as standard asynchronous transfer mode (ATM). Such a geographically dispersed switching system comprises a main telecommunication switch that provides the overall feature control for the system and remote switches that can be dispersed at great distances from the main telecommunication switch. Such a geographically dispersed system is described in U.S. patent application Ser. No. 09/718,909 filed on Nov. 22, 2000, which is hereby incorporated by reference. Such a geographically dispersed switching system allows individuals utilizing telephone sets directly connected to the remote switch to perform as if their telephone set was directly connected to the main telecommunication switch itself. The problem that arises is that when a user of the remote switch wishes to place a telephone call to a service system of the main telecommunication switch such as a voice mail system (VMS) from a local telephone that interconnects to the remote switch via a public switching office such as a central office. The central office is interconnected to the remote switch via trunks. The user of the local system can access the VMS system by placing a long distance call to the VMS system which incurs long distance charges and the user has to dial additional digits. In addition, if the local user that is utilizing a telephone set connected to the central office wishes to place a telephone call to an extension on the main telecommunication switch or an extension on another remote switch, again the user must place a long distance telephone call. There is no convenient mechanism that allows the local user calling from a telephone set connected to a central office to readily utilize the transmission capabilities of the geographically dispersed telecommunication switching system.  
         SUMMARY OF THE INVENTION  
         [0003]    The foregoing problems are solved and a technical advance is achieved by an apparatus and method that utilize an invisible agent within a remote switch to allow the redirection of calls received from a telephone set connected to a public telephone network to a main switching system.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0004]    [0004]FIG. 1 illustrates an embodiment of the invention;  
         [0005]    [0005]FIG. 2 illustrates an embodiment of a remote switch utilized in the invention;  
         [0006]    [0006]FIG. 3 illustrates, in flow chart form, an embodiment of operations for implementing the invention. 
     
    
     DETAILED DESCRIPTION  
       [0007]    [0007]FIG. 1 illustrates an embodiment of the invention. Remote switch  102  through remote switch  108  and Enterprise communication system  109  (as a main telecommunication switch) along with voice mail system (VMS)  113  form a geographically dispersed telecommunication switching system. For example, Enterprise communication system  109  could be in the United States along with remote switch  108  whereas remote switch  102  is located in the United Kingdom. The significance of this is that the dialing plan of the United States is different than the dialing plan of the United Kingdom. Advantageously, to gain access to VMS  113 , a user of telephone  103  places a call to an extension number of agent  116  in remote switch  102  via central office  101  (central switching system) and trunk  107 . Remote switch  102  is responsive to the dialing of this extension to terminate the call on agent  116 . In response to the call, agent  116  puts telephone set  103  on hold and dials the extension for VMS  113 . A call is set up between agent  116  to VMS  113  via WAN  106 . After this call has been set up, agent  116  transmits a call transfer message to the controller of remote switch  102  which is responsible to the transfer message to connect telephone set  103  to the call that had been previously set up with VMS  113  by implementing a call transfer feature. Advantageously, the implementation of this operation requires no modification of the software of remote switch  102  or Enterprise communication system  109 . When agent  116  placed the call to VMS  113 , Enterprise communication system  109  returned dial tone to agent  116  signaling that agent  116  could commence the dialing of the extension for VMS  113 .  
         [0008]    An embodiment of FIG. 1 allows a user of telephone set  103  to place a call to telephone  114  connected to Enterprise communication system  109  or telephone set  112  interconnected to remote switch  108 . In this operation, the user of telephone set  103  places a call to agent  117 . Agent  117  is responsive to this call from telephone set  103  to transmit a call origination to Enterprise communication system  109  and to transmit a redirect message to the control software controlling the operation of remote switch  102 . The control software is responsive to this redirect message to interconnect the call path from telephone set  103  to the call path that has been set up to Enterprise communication system  109  by controlling the network of remote switch  102 . The result is that telephone set  103  is now directly receiving dial tone (call proceed message) from Enterprise communication system  109  and can proceed to dial the extension number for either telephone set  114  or  112 . In response to this dialed extension number, Enterprise communication system  109  will establish the call path through remote switch  102 , Enterprise communication system  109 , or remote switch  108 .  
         [0009]    [0009]FIG. 2 illustrates in greater detail remote switch  102 . DSP pool  222  consists of DSPs  209 - 211  which are controlled by main CPU  201  via MPU bus  204 . Router  221  comprises main CPU  201  that provides overall control of remote switch  102 . Main CPU  201  executes control software module  226 , agent software module  116 , and agent software module  117 . Time slot interchange (TSI)  206  provides a mechanism for interexchanging time slots on local bus  225  and MPU bus  204 . In addition, TSI  206  can be utilized to interexchange time slots that are being received from telecommunication terminals such as telephone set  104  via line circuits  117  and trunk circuits  218 . This provides remote switch  102  with the capability of performing local circuit switching. Ethernet interface  202  interfaces local LAN  224  to bus  204 . Local IP telephone sets can be connected to LAN  224 . In addition, WAN interface  203  interconnects bus  204  to WAN  106 . Bus  204  is the overall informational highway that is used to communicate both control and bearer information within router  221 .  
         [0010]    DSP pool  222  comprises DSPs  209 - 211  that are under control of main CPU  201  to perform the necessary coding and conversion tasks.  
         [0011]    Circuit switch interface  223  comprises elements  212 - 218 . Controller  212  provides overall control of circuit switch interface  223 . Bus interface  213  interfaces control bus  214  and TDM bus  216  with local bus  225 . Control bus  214  is utilized to communicate control information between line circuits  217  and trunk circuits  218  and controller  212 . TDM bus  216  is utilized to communicate digitally encoded speech or data samples with lines circuits  217  and trunk circuits  218 . Line circuits  217  are utilized to provide termination for telecommunication terminals; whereas, trunk circuits  218  terminate trunks with the public telephone switching network  101 .  
         [0012]    Software module control  226  provides the overall control of remote switch  102  in response to stimuli received from units that are part of remote switch  102  and from control messages received from main Enterprise communication system  109 . Consider now the operation previously discussed of connecting a user of telephone set  103  connected to central office  101  to voice mail system  113  via remote switch  102 , WAN  106 , and Enterprise communication system  109 . When the user of telephone set  103  dials the telephone number associated with agent  116 , control module  226  terminates the control portion of this call on agent module  116  utilizing techniques well known to those skilled in the art. Agent  116  then transmits the necessary control messages to control  226  to establish a telephone call to voice messaging system  113 . Control  226  performs this operation by interactions with Enterprise communication system  109 . After the initial call set up, agent  116  then transmits a message to initiate a call transfer to control  226 . Control  226  interacts with Enterprise communication system  109  to accomplish the call transfer. Enterprise communication system  109  in response to messages from control  226  transmits messages to control  226  that causes control  226  to establish a connection between trunk  107  and voice mail system  113  with telephone set  103 . The interconnection of voice mail system  113  and telephone set  103  is accomplished by control  226  sending the necessary control messages to controller  212  which controls TDM bus  216 . In response to these control signals, a path is set up via TDM bus  216 , bus interface  213 , TSI  206 , MPU bus  204 , WAN interface  203  to WAN  106  and then to voice mail system  113  via Enterprise communication system  109 . The operation of these components is described in detail in the previously incorporated patent application.  
         [0013]    Consider now in greater detail the operation of the user of telephone set  103  placing a call to telephone set  114  connected to Enterprise communication system  109  or to telephone set  112  interconnected to remote switch  108 . The call is received by remote switch  102  from central office  101  via trunk circuits  218 . Control  226  is responsive to the dialed telephone number of this call to interconnect the call to agent  117 . Agent  117  then instructs control  226  to transmit a call set up message to Enterprise communication system  109  via MPU bus  204 , WAN interface  203 , and WAN  106 . In response to this call set up message, Enterprise communication system  109  transmits back a dial tone or in the case of ISDN signaling, the acknowledgment of the call set up message (call proceed message). In response, agent  113  instructs control  226  to interconnect via TDM bus  216  and relay any ISDN messages to trunk circuits  218  for subsequent relaying to central office  101  and telephone set  103 . The paths including a talk path and a signaling path is then established from telephone set  103  via central office  101 , trunk circuits  218 , and TDM bus  216 , bus interface  213 , TSI  206 , MPU bus  204 , WAN interface  203 , and WAN  106  to Enterprise communication system  109 . Enterprise communication system  109  then proceeds with the set up of the call receiving control signals from telephone set  103 .  
         [0014]    After being started in block  301 , decision block  302  determines if there is an incoming call. If the answer is no, block  312  performs normal processing before returning control back to decision block  302 . If the answer in decision block  302  is yes, control is transferred decision block  303  which determines if the incoming call is for agent  116 . If the answer is yes in decision block  303 , block  304  places the incoming call on hold. Block  306  then sets up a call to the voice messaging system. Finally, block  307  transfers the incoming call to the voice messaging system before returning control back to decision block  302 .  
         [0015]    Returning to decision block  303 , if the answer in decision block  303  is no, decision block  308  determines if the call is for agent  117 . If the answer is no, block  313  performs normal processing before returning control back to decision block  302 . If the answer in decision block  308  is yes, block  309  sets up a call path to the central switch which in the previous example had been Enterprise communication system  109 . After the call path has been set up in block  309 , block  311  redirects the incoming call to the call path before returning control back to decision block  302 .  
         [0016]    Of course, various changes and modifications to the illustrative embodiment described above will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the invention and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the following claims except in so far as limited by the prior art.