Method and apparatus for providing interoperation between a digital communication system and a public switched telephone network

Abstract

An interworking unit ( 14 ) for providing an interface between a digital communication network ( 12 ) and a public switched telephone network (PSTN) ( 16 ) includes a de-vocoder ( 30 ), a protocol termination unit ( 32 ), and a signal combiner ( 34 ) for processing signals being transferred from the digital network ( 12 ) to the PSTN ( 16 ). A digital communication signal received by the interworking unit ( 14 ) from the digital network ( 12 ) is processed by both the de-vocoder ( 30 ) and the protocol termination unit ( 32 ). The outputs of the de-vocoder ( 30 ) and the protocol termination unit ( 32 ) are then combined into a uniquely formatted signal that is then delivered into the PSTN ( 12 ). Similar functionality is also provided for processing signals in the reverse direction. The interworking unit 14 is capable of processing signals traversing the interface between the networks ( 12, 16 ) without a priori knowledge of the signal type being processed.

1. An interworking subsystem for providing interoperation between a digital communication network and a public switched telephone network (PSTN), said interworking subsystem comprising:
 an input for receiving a first communication signal from the digital communication network;  
 a de-vocoder for performing a de-vocoding operation on said first communication signal to generate a first output signal, wherein said first output signal includes a plurality of pulse code modulation (PCM) samples;  
 a protocol termination unit for performing a protection protocol termination operation on said first communication signal to generate a second output signal, wherein said second output signal includes a stream of digital data bits; and  
 a signal combiner for combining said first output signal and said second output signal into a composite signal for delivery to a destination user within the PSTN, wherein said signal combiner overlays said stream of digital data bits onto said plurality of PCM samples.  
 
     
     
       2. The interworking subsystem claimed in  claim 1 , wherein said de-vocoder and said protocol termination unit each operate upon said first communication signal regardless of a signal type of said first communication signal. 
     
     
       3. The interworking subsystem claimed in  claim 1 , further comprising:
 a second input for receiving a second communication signal from the PSTN;  
 a signal analyzer for analyzing said second communication signal to determine whether said second communication signal includes digital data;  
 a data extractor for extracting digital data from said second communication signal when said signal analyzer detects digital data therein; and  
 a protocol unit for applying a system-native digital protocol associated with the digital communication network to said digital data to generate a protocol protected digital data signal for delivery to a user within the digital communication network.  
 
     
     
       4. The interworking subsystem claimed in  claim 3 , further comprising a vocoder for performing a vocoding operation on said second communication signal when said signal analyzer does not detect digital data within said second communication signal. 
     
     
       5. An interworking subsystem for providing interoperation between a digital communication network and a public switched telephone network (PSTN), said interworking subsystem comprising:
 an input for receiving a first communication signal from the digital communication network;  
 a de-vocoder for performing a de-vocoding operation on said first communication signal to generate a first output signal, wherein said first output signal includes a plurality of pulse code modulation (PCM) samples;  
 a protocol termination unit for performing a protection protocol termination operation on said first communication signal to generate a second output signal, wherein said second output signal includes a stream of digital data bits; and  
 a signal combiner for combining said first output signal and said second output signal into a composite signal for delivery to a destination user within the PSTN, wherein said signal combiner inserts individual data bits from said stream of digital data bits into predetermined bit positions within the plurality of PCM samples.  
 
     
     
       6. The interworking subsystem claimed in  claim 5 , wherein:
 said signal combiner inserts data bits into the predetermined bit positions of the plurality of PCM samples only when a signal received by the interworking subsystem from the destination user within the PSTN includes digital data.  
 
     
     
       7. The interworking subsystem claimed in  claim 5 , wherein said de-vocoder and said protocol termination unit each operate upon said first communication signal regardless of a signal type of said first communication signal. 
     
     
       8. The interworking subsystem claimed in  claim 5 , further comprising:
 a second input for receiving a second communication signal from the PSTN;  
 a signal analyzer for analyzing said second communication signal to determine whether said second communication signal includes digital data;  
 a data extractor for extracting digital data from said second communication signal when said signal analyzer detects digital data therein; and  
 a protocol unit for applying a system-native digital protocol associated with the digital communication network to said digital data to generate a protocol protected digital data signal for delivery to a user within the digital communication network.  
 
     
     
       9. The interworking subsystem claimed in  claim 8 , further comprising a vocoder for performing a vocoding operation on said second communication signal when said signal analyzer does not detect digital data within said second communication signal. 
     
     
       10. A method for providing interoperation between a digital communication network and a public switched telephone network (PSTN), said method comprising:
 receiving a system-native digital communication signal from the digital communication network;  
 processing the system-native digital communication signal using a de-vocoding routine to generate a first intermediate signal, wherein said first intermediate signal includes a plurality of pulse code modulation (PCM) samples;  
 processing the system-native digital communication signal using a protocol termination routine to generate a second intermediate signal, wherein said second intermediate signal includes a stream of digital data bits; and  
 combining said first and second intermediate signals into a composite signal for delivery into the PSTN, wherein said step of combining includes distributing individual bits from said stream of digital data bits into predetermined bit positions within said PCM samples.  
 
     
     
       11. A method for providing interoperation between a digital communication network and a public switched telephone network (PSTN), said method comprising:
 receiving a system-native digital communication signal from the digital communication network;  
 processing the system-native digital communication signal using a de-vocoding routine to generate a first intermediate signal, wherein said first intermediate signal includes a plurality of pulse code modulation (PCM) samples;  
 processing the system-native digital communication signal using a protocol termination routine to generate a second intermediate signal, wherein said second intermediate signal includes a stream of digital data bits; and  
 combining said first and second intermediate signals into a composite signal for delivery into the PSTN, wherein said step of combining includes inserting successive bits from said stream of digital data bits into least significant bit (LSB) positions of successive PCM samples.  
 
     
     
       12. A method for formatting data for delivery through a public switched telephone network (PSTN), comprising:
 providing PCM samples, each of said PCM samples having a plurality of bit positions including a least significant bit (LSB) position, wherein said step of providing PCM samples includes acquiring an analog audio signal and sampling said analog audio signal at a predetermined sampling rate;  
 providing a stream of user data bits; and  
 substituting individual user data bits from said stream of user data bits into predetermined bit positions of said PCM samples before delivering said PCM samples through the PSTN.  
 
     
     
       13. The method claimed in  claim 12 , wherein said step of substituting includes substituting individual user data bits from said stream of user data bits into the LSB positions of said PCM samples. 
     
     
       14. The method claimed in  claim 13 , wherein said step of substituting includes substituting data bits in a sequential manner. 
     
     
       15. The method claimed in  claim 12 , wherein said step of providing PCM samples includes receiving a digital communication signal from a digital communication network and processing said digital communication signal using a de-vocoding algorithm. 
     
     
       16. The method claimed in  claim 12 , wherein said step of providing a stream of data bits includes receiving a digital communication signal from a digital communication network and removing a system-native protection protocol from said digital communication signal. 
     
     
       17. The method claimed in  claim 12 , wherein said step of providing a stream of data bits includes providing a computer data file having data to be transferred to a remote location and reading said computer data file. 
     
     
       18. A computer readable medium having a program stored thereon for implementing the method claimed in  claim 12  when executed within a digital processor. 
     
     
       19. A communication device having a digital processor and a computer readable medium, said computer readable medium having a program stored thereon for implementing the method claimed in  claim 12  when executed within said digital processor. 
     
     
       20. A method for formatting data for delivering through a public switched telephone network (PSTN), comprising:
 providing PCM samples, each of said PCM samples having a plurality of bit positions including a least significant bit (LSB) position, wherein said step of providing PCM samples includes generating dummy samples including simulated audio information;  
 providing a stream of user data bits; and  
 substituting individual user data bits from said stream of user data bits into predetermined bit positions of said PCM samples before delivering said PCM samples through the PSTN.  
 
     
     
       21. The method claimed in  claim 20 , wherein said step of substituting includes substituting individual user data bits from said stream of user data bits into the LSB positions of said PCM samples. 
     
     
       22. The method claimed in  claim 21 , wherein said step of substituting includes substituting data bits in a sequential manner. 
     
     
       23. The method claimed in  claim 20 , wherein said step of providing PCM samples includes receiving a digital communication signal from a digital communication network and processing said digital communication signal using a de-vocoding algorithm. 
     
     
       24. The method claimed in  claim 20 , wherein said step of providing a stream of data bits includes receiving a digital communication signal from a digital communication network and removing a system-native protection protocol from said digital communication signal. 
     
     
       25. The method claimed in  claim 20 , wherein said step of providing a stream of data bits includes providing a computer data file having data to be transferred to a remote location and reading said computer data file. 
     
     
       26. A computer readable medium having a program stored thereon for implementing the method claimed in  claim 20  when executed within a digital processor. 
     
     
       27. A communication device having a digital processor and a computer readable medium, said computer readable medium having a program stored thereon for implementing the method claimed in  claim 20  when executed within said digital processor. 
     
     
       28. An apparatus for providing interoperation between a first user device coupled to a first network and a second user device coupled to a second network, comprising:
   a de - vocoder configured to generate a pulse code modulation  ( PCM )  audio signal from a digital communication network signal transmitted by the first user device;        a protocol termination unit configured to remove protocol information from the digital communication network signal and generate a data signal; and        a signal combiner, coupled to the de - vocoder and the protocol termination unit, configured to combine the PCM audio signal and the data signal and generate a composite signal for delivery to the second user device.     
     
     
       29. The apparatus claimed in  claim 28 , further comprising:
   an input, coupled to the de - vocoder and the protocol termination unit, configured to receive wireless communications from the first network.     
     
     
       30. The apparatus claimed in  claim 28 , wherein the first user device is one of a personal computing device, a telephone, and a pager. 
     
     
       31. The apparatus claimed in  claim 28 , wherein the signal combiner overlays the data signal onto the PCM audio signal. 
     
     
       32. The apparatus claimed in  claim 28 , wherein the signal combiner inserts data of the data signal into predetermined information data positions of the PCM audio signal. 
     
     
       33. An apparatus for providing interoperation between a first user device coupled to a first network and a second user device coupled to a second network, comprising:
   a second analysis unit configured to detect and extract a data signal from a pulse code modulation  ( PCM )  audio signal transmitted by the first user device;        a protocol unit, coupled to the signal analysis unit, configured to add protocol information to the extracted data signal and generate a formatted data signal for delivery to the second user device; and        a vocoder, coupled to the signal analysis unit, configured to process the PCM audio signal using a vocoding algorithm and generate a vocoded voice signal for delivery to the second user device.     
     
     
       34. The apparatus claimed in  claim 33 , wherein the data signal is overlaid onto the PCM audio signal. 
     
     
       35. The apparatus claimed in  claim 33 , wherein the data signal resides in predetermined information data positions of the PCM audio signal. 
     
     
       36. An apparatus for providing interoperation between a first user device coupled to a first network and a second user device coupled to a second network, comprising:
   a de - vocoder configured to generate a first pulse code modulation  ( PCM )  audio signal from a digital communication network signal transmitted by the first user device;        a protocol termination unit configured to remove protocol information from the digital communication network signal and generate a first data signal;        a signal combiner, coupled to the de - vocoder and the protocol termination unit, configured to combine the first PCM audio signal and the first data signal and generate a composite signal for delivery to the second user device;        a signal analysis unit configured to extract a second data signal from a second PCM audio signal transmitted by the second user device;        a protocol unit, coupled to the signal analysis unit, configured to add protocol information to the second data signal and generate a formatted data signal for delivery to the first user device; and        a vocoder, coupled to the signal analysis unit, configured to process the second PCM audio signal using a vocoding algorithm and generate a vocoded voice signal for delivery to the first user device.     
     
     
       37. The apparatus claimed in  claim 36 , further comprising:
   an input, coupled to the de - vocoder and the protocol termination unit, configured to receive wireless communications from the first network.     
     
     
       38. A method for providing interoperation between a first user device coupled to a first network and a second user device coupled to a second network, comprising:
   generating a pulse code modulation  ( PCM )  audio signal from a digital communication network signal transmitted by the first user device;        removing protocol information from the digital communication network signal to form a data signal; and        combining the PCM audio signal and the data signal to form a composite signal for delivery to the second user device.     
     
     
       39. The method claimed in  claim 38 , further comprising:
   extracting a second data signal from a second PCM audio signal transmitted by the second user device;        adding protocol information to the second data signal to form a formatted data signal for delivery to the first user device; and        processing the second PCM audio signal using a vocoding algorithm to generate a vocoded voice signal for delivery to the first user device.     
     
     
       40. The method claimed in  claim 38 , wherein the composite signal comprises an encrypted message. 
     
     
       41. The method claimed in  claim 40 , wherein the encrypted message comprises a voice message. 
     
     
       42. A method for formatting data, comprising:
   generating a pulse code modulation  ( PCM )  audio signal from a digital communication network signal, wherein the PCM audio signal includes a plurality of information data positions;        generating a data signal from the digital communication network signal, wherein the data signal includes a stream of user data; and        substituting user data into predetermined information data positions of the PCM audio signal to form a formatted signal for delivery to a user device.     
     
     
       43. A computer readable medium having computer program logic embodied therein for causing a processor to facilitate interoperation between a first user device coupled to a first network and a second user device coupled to a second network, the computer program logic comprising:
   first logic configured to cause the processor to generate a pulse code modulation  ( PCM )  audio signal from a digital communication network signal transmitted by the first user device;        second logic configured to cause the processor to remove protocol information from the digital communication network signal to form a data signal; and        third logic configured to cause the processor to combine the PCM audio signal and the data signal to form a composite signal for delivery to the second user device.     
     
     
       44. The computer readable medium claimed in  claim 43 , wherein the data signal is overlaid onto the PCM audio signal. 
     
     
       45. The computer readable medium claimed in  claim 43 , wherein the data signal resides in predetermined information data positions of the PCM audio signal. 
     
     
       46. A system for providing interoperation between a first user device coupled to a first network and a second user device coupled to a second network, comprising:
   a first module configured to generate a pulse code modulation  ( PCM )  audio signal from a digital communication network signal transmitted by the first user device;        a second module configured to remove protocol information from the digital communication network signal and generate a data signal; and        a third module, coupled to the first module and the second module, configured to combine the PCM audio signal and the data signal and generate a composite signal for delivery to the second user device.     
     
     
       47. The system claimed in  claim 46 , wherein the third module overlays the data signal onto the PCM audio signal. 
     
     
       48. The system claimed in  claim 46 , wherein the third module inserts data of the data signal into predetermined information data positions of the PCM audio signal. 
     
     
       49. A system for providing interoperation between a first user device coupled to a first network and a second user device coupled to a second network, comprising:
   a first module configured to detect and extract a data signal from a pulse code modulation  ( PCM )  audio signal transmitted by the first user device;        a second module, coupled to the first module, configured to add protocol information to the extracted data signal and generate a formatted data signal for delivery to the second user device; and        a third module, coupled to the first module, configured to process the PCM audio signal using a vocoding algorithm and generate a vocoded voice signal for delivery to the second user device.     
     
     
       50. The system claimed in  claim 49 , wherein the data signal is overlaid onto the PCM audio signal. 
     
     
       51. The system claimed in  claim 49 , wherein the data signal resides in predetermined information data positions of the PCM audio signal. 
     
     
       52. A system for providing interoperation between a first user device coupled to a first network and a second user device coupled to a second network, comprising:
   a first module configured to generate a first pulse code modulation  ( PCM )  audio signal from a digital communication network signal transmitted by the first user device;        a second module configured to remove protocol information from the digital communication network signal and generate a first data signal;        a third module, coupled to the first module and the second module, configured to combine the first PCM audio signal and the first data signal and generate a composite signal for delivery to the second user device;        a fourth module configured to extract a second data signal from a second PCM audio signal transmitted by the second user device;        a fifth module, coupled to the fourth module, configured to add protocol information to the second data signal and generate a formatted data signal for delivery to the first user device; and        a sixth module, coupled to the fourth module, configured to process the second PCM audio signal using a vocoding algorithm and generate a vocoded voice signal for delivery to the first user device.     
     
     
       53. The system claimed in  claim 52 , wherein the first data signal is overlaid onto the first PCM audio signal. 
     
     
       54. The system claimed in  claim 52 , wherein the first data signal resides in predetermined information data positions of the first PCM audio signal.