Abstract:
Providing multiple line functionality using alternative network telephony is disclosed. A local telephone installation comprises a first local telephone equipment associated with a first local node, a second telephone equipment associated with a second local node, and local telephone wiring connected to the first and second local nodes. The local telephone installation is associated for purposes of the public switched telephone network (PSTN) with a single telephone line. A request from a calling party to establish a connection with the local telephone installation is received at a third local node. It is determined whether the calling party desires to establish a connection to (1) a first telephone extension associated with the first local node or (2) a second telephone extension associated with the second local node. A connection is established from the third local node to the desired extension over the local telephone wiring in a manner that does not affect the other extension.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation of co-pending U.S. patent application Ser. No. 10/388,605 entitled PROVIDING MULTIPLE LINE FUNCTIONALITY USING ALTERNATIVE NETWORK TELEPHONY filed Mar. 13, 2003 which is incorporated herein by reference for all purposes.  
         [0002]     This application is related to co-pending U.S. patent application Ser. No. 10/389,277 entitled FAILSAFE CONFIGURATION FOR ALTERNATIVE NETWORK TELEPHONY filed Mar. 13, 2003, which is incorporated herein by reference for all purposes; and co-pending U.S. patent application Ser. No. 10/388,767 entitled SELECTIVE PROCESSING OF CALLS USING ALTERNATIVE NETWORK TELEPHONY filed Mar. 13, 2003, which is incorporated herein by reference for all purposes. 
     
    
     FIELD OF THE INVENTION  
       [0003]     The present invention relates generally to alternative network telephony. More specifically, providing multiple line functionality using alternative network telephony is disclosed.  
       BACKGROUND OF THE INVENTION  
       [0004]     In recent years alternative network telephony, using a network other than the public switched telephone network (PSTN) to enable two or more parties to carry on a conversation in real time, has become increasingly popular. The advent of high-speed access to networks, such as the Internet, has further fueled this trend. Telephone functionality has been provided using personal computers (PC&#39;s) or computer workstations connected via the Internet and/or other networks, often through high-speed connections such as cable modems or digital subscriber line (DSL) connections. Telephone functionality has also been provided via cable television networks through television set top boxes, for example.  
         [0005]     In many cases, a packet switched network protocol, such as the Internet protocol (IP) is used to provide alternative network telephony (e.g., IP telephony). Under such a protocol, the analog audio signal generated by a speaking call participant is digitized and sent via the alternative network from the sending station to the receiving station(s) in one or more data packets conforming to the applicable protocol. At the receiving end, the data typically is reassembled, if necessary, and converted back to an analog audio signal. The data is then typically delivered to the recipient via an audio output device, such as one or more speakers, a headset, or a telephone handset or other output device.  
         [0006]     It would be desirable for cable television service providers, providers of interactive television services and/or equipment, and/or other providers or potential providers of alternative network telephony equipment and services to have a way to compete effectively with more traditional providers of long distance and/or local telephone service. Such competition may bring lower prices, better and expanded service, and more choice to consumers.  
         [0007]     One way that alternative network telephony might be used to enhance service is by providing the functionality of multiple telephone extensions without requiring multiple lines connected to the public switched telephone network (PSTN). Complex switches, such as private branch exchange (PBX) switches, have been provided to route calls coming in on a single PSTN line to two or more internal lines. However, such switches typically are expensive to acquire and install, making their use by consumers and small businesses impractical in many cases.  
         [0008]     Therefore, there is a need for a way to use alternative network telephony to provide PBX-type functionality, specifically the ability to make and receive calls on multiple internal lines while having only a single PSTN line.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     The present invention will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which:  
         [0010]      FIG. 1  is a schematic diagram illustrating a system used in one embodiment to use alternative network telephony to provide multiple extension functionality via a single telephone line connection to the PSTN.  
         [0011]      FIG. 2  is a schematic diagram of a dongle used in one embodiment to provide multiple extension functionality using alternative network telephony, such as the first dongle  104  and the second dongle  110  of  FIG. 1 .  
         [0012]      FIG. 3  is a schematic diagram of a call processing system for using alternative network telephony to provide multiple extension functionality, such as the call processing system  112  of  FIG. 1 .  
         [0013]      FIG. 4  is a flowchart illustrating a process implemented in one embodiment on a call processing system, such as the call processing system  112  of  FIG. 1 , to enable a user to place an outgoing telephone call either from the first telephone handset  102  or from the second telephone handset  108  via the call processing system  112  in a system configured to use alternative network telephony to provide multiple extension functionality.  
         [0014]      FIG. 5  is a flowchart illustrating a process implemented in one embodiment on a call processing system to receive telephone calls on a system configured to provide multiple extension functionality using alternative network telephony.  
         [0015]      FIG. 6  is a flowchart illustrating a process implemented in one embodiment on the call processing system, such as call processing system  112  of  FIG. 1 , to connect and process calls as in step  410  of  FIG. 4  and step  514  of  FIG. 5 .  
     
    
     DETAILED DESCRIPTION  
       [0016]     It should be appreciated that the present invention can be implemented in numerous ways, including as a process, an apparatus, a system, or a computer readable medium such as a computer readable storage medium or a computer network wherein program instructions are sent over optical or electronic communication links. It should be noted that the order of the steps of disclosed processes may be altered within the scope of the invention.  
         [0017]     A detailed description of one or more preferred embodiments of the invention are provided below along with accompanying figures that illustrate by way of example the principles of the invention. While the invention is described in connection with such embodiments, it should be understood that the invention is not limited to any embodiment. On the contrary, the scope of the invention is limited only by the appended claims and the invention encompasses numerous alternatives, modifications and equivalents. For the purpose of example, numerous specific details are set forth in the following description in order to provide a thorough understanding of the present invention. The present invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the invention has not been described in detail so that the present invention is not unnecessarily obscured.  
         [0018]     Providing multiple line functionality using alternative network telephony is disclosed. Each of a plurality of telephones is connected to an alternative network telephony call processing system via a dongle interposed between the telephone and the in-building telephone wiring. The dongle incorporates a frequency shifter that shifts the audio signal generated by each telephone by a specific amount associated with the extension to which the telephone corresponds. The call processing system uses the magnitude of the frequency shift to associate audio data received via the in-building telephone wiring with the corresponding extension, enabling the system to process calls on separate telephones, either individually or at the same time.  
         [0019]      FIG. 1  is a schematic diagram illustrating a system used in one embodiment to use alternative network telephony to provide multiple extension functionality via a single telephone line connection to the PSTN. The system comprises a first telephone handset  102  connected via a first dongle  104  to internal telephone wiring  106 . The system further comprises a second telephone handset  108  connected via a second dongle  110  to the internal telephone wiring  106 . An alternative network call processing system  112  also is connected to the internal telephone wiring  106 . The alternative network call processing system  112  is in addition connected to an alternative network, such as the Internet, via an alternative network connection  114 . In one embodiment, the alternative network call processing system  112  comprises a personal computer and the connection  114  to the alternative network comprises a cable or other modem connection. In one embodiment, the alternative network call processing system  112  comprises a television set top box connected via the network connection  114  to the alternative network via a cable modem or other modem. In one embodiment, the first dongle  104  is configured to apply a first frequency shift to communications to and from the first telephone handset  102 . More particularly, the dongle  104  is configured in one embodiment to shift audio signals received from the telephone handset  102  by a first prescribed amount prior to outputting the audio signal to the internal telephone wiring  106 . In one embodiment, the first dongle  104  is further configured to downshift frequency-shifted audio signals received at the dongle  104  via the internal telephone wiring  106  prior to providing such audio signals to the telephone handset  102 .  
         [0020]     In one embodiment, the second dongle  110  is configured to apply a second frequency shift to audio signals received from and sent to the second telephone handset  108 . That is, for audio signals received at the second dongle  110  from the second telephone handset  108 , the audio signal is shifted by a second frequency shift prior to being provided as output from the second dongle  110  to the internal telephone wiring  106 . In one embodiment, the second dongle  110  is further configured to downshift frequency-shifted audio signals received at the second dongle from the internal telephone wiring  106  by the second frequency shift prior to providing the downshifted incoming audio signal to the second telephone handset  108 . In one embodiment, the first frequency shift applied by the first dongle  104  is different in magnitude from the second frequency shift applied by the second dongle  110  in order to enable components of the system to differentiate between frequency-shifted signals associated with the first telephone handset  102  and those associated with the second telephone handset  108 , as described more fully below. For example, in one embodiment the first frequency shift may be 100 MHz and the second frequency shift may be 200 MHz. In such an embodiment, the first dongle  104  would shift audio signals generated by the handset  102  up by 100 MHz prior to placing the frequency shifted signal on the internal telephone wiring  106 , and the first dongle would downshift frequency shifted audio signals received via the internal telephone wiring  106  by 100 MHz prior to delivering such signals to the handset  102 . Likewise, the second dongle  110  would apply a 200 MHz frequency shift to audio signals provided to and from the second telephone handset  108 .  
         [0021]     Note that while two handsets are shown in the embodiment illustrated in  FIG. 1 , any number of lines may be added, so long as each handset and/or group of handsets associated with a particular extension are provided with a dongle or other device configured to apply a frequency shift associated with the extension to audio signals provided to or from the handset or group of handsets. Also, while a handset is shown in  FIG. 1 , any device capable of being connected to a telephone line may be substituted for one or more of the handsets, as will be readily apparent to those of skill in the art. For example, other types of equipment used for voice communication, a fax machine, or other equipment such as modems or other devices that use telephone lines to exchange, receive, and/or deliver data of any type via telephone lines.  
         [0022]     The system shown in  FIG. 1  further comprises a filter  116  configured to prevent frequency-shifted audio signals on the internal telephone wiring  106  from being passed to the PSTN via external PSTN connection  118 . In this manner, frequency-shifted signals passed via the internal telephone wiring  106 , such as signals passed between the first telephone handset  102  and the alternative network call processing system  112  or signals passed between the second telephone handset  108  and the alternative network call processing system  112 , are not received by the PSTN, and as a result the PSTN neither detects nor interferes with the use of the internal telephone wiring  106  to transmit such frequency-shifted signals between the system components.  
         [0023]     In one embodiment, the alternative network call processing system  112  is configured to receive frequency-shifted signals placed on the internal telephone wiring  106  either by first telephone handset  102  via dongle  104  or by the second telephone handset  108  via dongle  110 . In one embodiment, the alternative network call processing system  112  is configured to determine which telephone handset a frequency-shifted audio signal received via the internal telephone wiring  106  is associated with based on the amount of the frequency shift applied to the received signal. That is, the alternative network call processing system  112  determines that a received frequency-shifted audio signal originated from the first telephone handset  102  if the amount of frequency shift applied to the signal as determined at the call processing system  112  is the same as the amount that is applied by the first dongle  104 .  
         [0024]     In one embodiment, the call processing system  112  is configured to connect and process telephone calls placed at either the first telephone handset  102  or the second telephone handset  108 , or both, via the alternative network in the manner well known in the art of alternative network telephony. During the processing of such a call, upon the receipt of audio data via the alternative network, the call processing system  112  is configured in one embodiment to determine which telephone extension the call data is associated with and to output such data as a frequency-shifted audio signal that has been shifted in frequency by the call processing system  112  by the amount associated with the telephone handset to which the audio signal is to be delivered, as described more fully below in connection with  FIGS. 4-6 .  
         [0025]      FIG. 2  is a schematic diagram of a dongle used in one embodiment to provide multiple extension functionality using alternative network telephony, such as the first dongle  104  and the second dongle  110  of  FIG. 1 . The dongle  202  comprises a phone line  204  connected to a telephone handset or other telephone equipment. The dongle  202  further comprises a telephone wiring connection  206  used to connect the dongle to the internal telephone wiring, such as the internal telephone wiring  106  of  FIG. 1 . The phone line  204  connected to the telephone handset enters the dongle and is connected to a switch  208 . In one embodiment, as shown in  FIG. 2 , the switch  208  has two positions. In a first position, marked “A” in  FIG. 2 , the phone line  204  is connected through a connector line  210  to a frequency shifter  212 . The frequency shifter  212  is connected via a line  214  to a band pass filter  216 . In one embodiment, the band pass filter  216  is bi-directional and allows to pass in either direction only signals that fall within a prescribed range of frequencies. In one embodiment, the band pass filter range of frequencies is more or less centered on the frequency corresponding to the magnitude of the frequency shift applied by the frequency shifter  212 . In one embodiment, the frequency shifter  212  is configured to shift an outgoing audio signal generated by the telephone handset connected to the phone line  204  by a prescribed amount. In one embodiment, the prescribed frequency shift may be on the order of 100-300 Megahertz. In one embodiment, the frequency shifter is further configured to downshift signals received from the internal telephone wiring via internal telephone wiring connection  206  and bandpass filter  216  by the same amount that outgoing signals are shifted up in frequency.  
         [0026]     The second position of the switch  208 , marked “B” in  FIG. 2 , may be used to connect the telephone handset connected to phone line  204  via a line  218  to a low pass filter  220  which connects via a line  222  to the internal telephone wiring via the connection  206 . In one embodiment, the line  222 , low pass filter  220 , and line  218 , and the path through said components and the switch  208  to the phone line  204  when the switch  208  is in the second position (i.e. the “B” position) may be used to allow the telephone handset to be connected to the phone line  204  to place and receive calls via the PSTN without applying any frequency shift to either incoming or outgoing audio signals. In one embodiment, it may be desirable to have such a path available as a default or failsafe path in the event of a failure of the alternative network call processing system  112 , as described more fully in co-pending application Ser. No. 10/389,277 entitled FAILSAFE CONFIGURATION FOR ALTERNATIVE NETWORK TELEPHONY, which is incorporated herein by reference above.  
         [0027]      FIG. 3  is a schematic diagram of a call processing system for using alternative network telephony to provide multiple extension functionality, such as the call processing system  112  of  FIG. 1 . The call processing system  112  is shown in  FIG. 3  as comprising a connection  302  to the internal telephone wiring  106 . Within the call processing system  112 , the line  302  connected to the internal telephone wiring is connected to a first band pass filter  304 , a second band pass filter  306 , and a low pass filter  308 . In one embodiment, the first band pass filter  304  is configured to allow to pass only frequency-shifted audio signals received via the internal telephone wiring  106  to which the first frequency shift applied by the first dongle  104  has been applied. Likewise, the second band pass filter  306  is configured to allow to pass only those frequency-shifted signals received via the internal telephone wiring  106  to which the second frequency shift applied by the second dongle  110  has been applied. The first band pass filter  304  is connected via connection  310  to a first frequency shifter  312 . The first frequency shifter  312  is connected via connection  314  to a call processor  316 . In one embodiment the first frequency shifter  312  is configured to downshift frequency-shifted audio signals received via line  310  by the first frequency shift applied by dongle  104 , and to provide the downshifted audio signal via connection  314  to the call processor  316 . In one embodiment, the call processor  316  associates the received audio signal with the first extension (i.e., the extension associated with the first telephone handset  102 ) by virtue of the fact that the audio signal is received by the call processor  316  via the connection  314 . For a received audio signal to be delivered to the first telephone handset  102 , the call processor  316  is configured in one embodiment to output the received audio signal via the line  314  to the first frequency shifter  312 . In one embodiment, the first frequency shifter  312  is configured to frequency shift an audio signal received on line  314  by the amount of the first frequency shift associated with the dongle  104  and the first telephone handset  102 , and to provide the frequency-shifted audio signal via the line  310  and the first band pass filter  304  to the internal telephone wiring  106  via the connection  302 . The frequency-shifted signal is then received by the dongle  104 , downshifted, and provided to the first telephone handset  102  as described above. Such a frequency-shifted signal intended for the first telephone handset  102  would not be passed by the dongle  110  to the second telephone extension  108  in one embodiment by operation of the band pass filter within said dongle, such as band pass filter of  216  of  FIG. 2 .  
         [0028]     Similar to the corresponding path for signals associated with the first telephone handset, the second band pass filter  306  is configured in one embodiment to pass only signals shifted by the second frequency shift, i.e., the frequency shift associated with the second dongle  110  and the second telephone handset  108  of  FIG. 1 . The second band pass filter  306  is connected via a connection  318  to a second frequency shifter  320 . The second frequency shifter  320  is connected via connection  322  to the call processor  316 . In one embodiment, the second frequency shifter  320  is configured to downshift frequency-shifted signals received by the call processing system  112  via the internal telephone wiring  106  by the amount of the second frequency shift and to provide the downshifted signal via the connection  322  to the call processor  316 . In one embodiment, the call processor  316  recognizes a signal received via the connection  322  from the second frequency shifter  320  as being a signal associated with the second telephone handset  108 . Incoming and outgoing signals associated with the second telephone handset would be processed by the call processor  316  in the same manner as described above for signals associated with the first telephone handset  102 , with the exception that the connections  322 , the frequency shifter  320 , the connection  318 , and the second band pass filter  306  would be used.  
         [0029]     The low pass filter  308  of  FIG. 3  is connected via the connection  324  to the call processor  316 . In one embodiment, the connection between the call processor  316  via the low pass filter  308  to the internal telephone wiring  106  via connection  302  is provided to enable the call processing system  112  to receive and place calls on behalf of a user of either the first telephone handset  102  or the second telephone handset  108  via the PSTN, using the process described above to pass audio signals to and from the applicable telephone handset in the form of frequency-shifted audio signals. Such proxying of calls via the PSTN is described more fully in co-pending application Ser. No. 10/388,767 entitled SELECTIVE PROCESSING OF CALLS USING ALTERNATIVE NETWORK TELEPHONY, which is incorporated herein by reference above.  
         [0030]      FIG. 4  is a flowchart illustrating a process implemented in one embodiment on a call processing system, such as the call processing system  112  of  FIG. 1 , to enable a user to place an outgoing telephone call either from the first telephone handset  102  or from the second telephone handset  108  via the call processing system  112  in a system configured to use alternative network telephony to provide multiple extension functionality. The process begins at step  402  in which the call processing system receives an indication that a telephone handset has been taken off the hook by a user. In step  404 , the call processing system receives frequency shifted dialed digits. In step  406 , the call processing system determines the extension used to dial the dialed digits. In one embodiment, as described above, the call processing system is configured to determine which extension was used to dial the frequency-shifted dialed digits by determining the amount of the frequency shift applied by the corresponding dongle to the dialed digits prior to their being placed as a frequency shifted signal on the internal telephone wiring  106 . In one embodiment, as described above in connection with  FIG. 3 , the call processor within the call processing system makes this determination based on which band pass filter and associated frequency shifter are used to process the signal and provide it to the call processor. Those of ordinary skill in the art will recognize that many other combinations of components may be used to enable the call processing system to associate the received digits with a particular extension.  
         [0031]     In step  408  of the process shown in  FIG. 4 , the call processing system sets a flag or status register associated with the extension that was used to dial the dialed number to indicate the status of the associated telephone handset as “busy”. In step  410 , the call processing system connects and processes the call in the manner well known in the art of alternative network telephony. The process of connecting and processing a call is illustrated more fully in  FIG. 6 , discussed below. In step  412 , the call processing system receives an indication that the call has been terminated by one or the other of the participants, in which case the process shown in  FIG. 4  ends in step  414 .  
         [0032]      FIG. 5  is a flowchart illustrating a process implemented in one embodiment on a call processing system to receive telephone calls on a system configured to provide multiple extension functionality using alternative network telephony. The process begins in step  502  in which the call processing system receives a “ring” signal or message and establishes a connection with the calling party. In one embodiment, the “ring” signal or message is received via the alternative network. In one alternative embodiment, the “ring” signal or message may be received via the alternative network if the call is being received via alternative network telephony or the “ring” signal may be received via the PSTN if the call has been placed via the PSTN. In step  504 , the call processing system provides to the calling party an audio message prompting the calling party to make a selection of the extension to which the calling party would like to be connected. In step  506 , the call processing system receives from the calling party an indication of the extension to which the calling party would like to be connected. In step  508 , the call processing system determines whether or not the selected extension is available. If it is determined in step  508  that the selected extension is not available, the call processing system in step  510  returns to the calling party a “busy” signal or message and the process ends in step  520 . If it is determined in step  508  that the selected extension is available, the process proceeds to step  512  in which the call processing system causes the selected extension to ring. In one embodiment, the call processing system is configured to ring the selected extension by sending to the selected extension a prescribed frequency-shifted ring signal. In one embodiment, the dongle associated with the selected telephone handset is configured to recognize the frequency-shifted ring signal and to cause the associated telephone handset to ring. In step  514  of the process shown in  FIG. 5 , the call processing system receives an indication that the telephone handset associated with the selected extension has been taken off the hook, and the call is connected and processed by the call processing system, as described more fully below in connection with  FIG. 6 . In step  516 , the call processing system receives an indication that the call has been terminated by one or the other of the call participants, in which case the process ends in step  520 .  
         [0033]      FIG. 6  is a flowchart illustrating a process implemented in one embodiment on the call processing system, such as call processing system  112  of  FIG. 1 , to connect and process calls as in step  410  of  FIG. 4  and step  514  of  FIG. 5 . The process begins with step  602  in which a connection is established. In one embodiment, the establishment of a connection in step  602  comprises making a table entry associating the calling party with the called party and/or extension. In one embodiment, establishing a connection in step  602  comprises creating a software object associated with the call, in which the software object associates the calling party and the called party and/or extension. In one embodiment, the step  602  comprises establishing an open and active end to end data path between the called party and the calling party, using alternative network telephony, if applicable, in the manner well known in the art of alternative network telephony and telephone communications generally.  
         [0034]     Steps  604 ,  606 , and  608  of  FIG. 6  describe the processing steps performed by the call processing system for audio data received from a remote party for delivery to either the first handset  102  or the second handset  108  of the system shown in  FIG. 1 . In step  604 , incoming audio data associated with a call is received via the alternative network. In one alternative embodiment, the incoming call data may be received either via the alternative network or via the PSTN. In step  606 , the received audio data is associated with the call to which it corresponds. In one embodiment, the call processing system associates the received audio data with the corresponding call based on the source from which the incoming audio data is received. In step  608 , the received audio data is output to the extension associated with the call. In one embodiment, digital audio data received via the alternative network is converted to an analog audio signal and then frequency shifted by the amount corresponding to the extension to which the received audio data is to be delivered prior to placing the frequency shifted audio signal on to the internal telephone wiring  106  for delivery via the appropriate dongle to the extension to which the audio signal is to be delivered. As described above, an audio signal shifted in frequency in the prescribed amount for the destination handset will be passed to the handset only by the dongle associated with the handset that corresponds to that particular frequency shift, and will not be delivered by any other dongles to their associated handsets. Likewise, the filter between the internal telephone wiring  106  and the PSTN, such as filter  116  of  FIG. 1 , will not allow the frequency-shifted audio signal to pass to the PSTN.  
         [0035]     Steps  610 ,  612 , and  614  describe the processing steps for outgoing audio data, i.e., audio signals received from the telephone handset associated with the call and intended for delivery to the remote call participant associated with the call. In step  610 , an outgoing audio signal is received via the internal telephone wiring  106  at the call processing system  112 . As described above, the outgoing audio signal would be received in the form of a frequency shifted analog audio signal. In step  612 , the received audio signal is associated with the call to which it pertains. In one embodiment, as described above, the received outgoing audio signal is associated with the call to which it pertains by determining the amount of frequency shift that was applied to the audio signal by the corresponding dongle prior to its being placed on the internal telephone wiring  106 , and identifying the extension to which that frequency shift corresponds. In step  614 , the outgoing audio data is sent to the remote destination associated with the call, i.e., the other call participant, either via the alternative network or via the PSTN, as applicable.  
         [0036]     The steps  604 ,  606 , and  608  for incoming audio data, and the steps  610 ,  612 , and  614  for outgoing audio data, are repeated as necessary to send and receive audio data between the call participants as the respective call participants speak, until an indication is received that the call has been terminated, as in step  412  of  FIG. 4  and step  416  of  FIG. 5 .  
         [0037]     As will be apparent to those of skill in the art, it is possible using the frequency shifting techniques described herein to process more than one call at a time without requiring multiple lines connected to the PSTN. For example, a first call may be taking place on a first virtual extension while a second call is taking place on a second virtual extension. The respective data associated with the respective calls will not be confused by the call processing system, which will distinguish between the two, as described above, based on the frequency shift applied to frequency shifted signals received by the system via the internal telephone wiring and in the case of data received from remote participants based on other data or information used by the call processing system to associate received data with the call to which it corresponds, such as based on the source from which it is received, etc.  
         [0038]     While certain of the examples described in detail above relate to a telephone call in which participants speak to each other, other types of calls and connections may be made, such as exchanging data other than voice data.  
         [0039]     While one or more embodiments described in detail herein may employ frequency shifting, the present disclosure contemplates and encompasses approaches in which other encoding techniques are used. The only requirement is that the alternative network call processing system must be able to distinguish between signals on the internal telephone wiring that are in the normal voice range, which are meant to be processed normally over the PSTN, and specially encoded signals which are meant to be processed not by the PSTN but instead by the alternative network call processing system; and, as among calls intended to be processed by alternative network telephony, the encoding must be such that the system can distinguish between call data associated with different virtual extensions. For example, and without limitation, any suitable type of frequency encoding may be used. In one embodiment, instead of using frequency shifting as described above an incoming or outgoing audio signal may be used to frequency modulate one or more carrier waves having a frequency outside the normal frequency range of a voice signal. In one such embodiment, frequency filters may be used to permit applicable components to either operate on, or ignore, a signal depending on the carrier frequency used, in a manner similar to the frequency shifting approach described above. In one embodiment, in the system of  FIG. 1  the dongles  104  and  110  are configured to encode and decode voice signals originated by and destined for the handset  102  and  108 , respectively, in accordance with the encoding method the remaining system components, such as alternative network call processing system  112 , are configured to use. For example, in one embodiment where frequency modulation encoding is used, the dongles  104  is configured to use a voice range audio signal generated by handset  102  to modulate a first carrier frequency sufficiently outside the normal voice range to enable the relevant remaining components to distinguish such an encoded signal from an unencoded a voice range audio signal, and the dongle  110  is configured to use a voice range audio signal generated by handset  108  to modulate a second carrier frequency sufficiently outside the normal voice range to enable the relevant remaining components to distinguish such an encoded signal from an unencoded a voice range audio signal and sufficient different from the first carrier frequency to enable the system to distinguish between encoded signals associated with handset  102  and those associated with handset  108 . In one embodiment, the dongles  104  and  110  are configured to receive a signal encoded using frequency modulation of a carrier signal having a frequency outside the normal voice range, demodulate the signal, and present the decoded original signal as audio output on handsets  102  and  108 , respectively, each being configured to decode only those encoded signals associated with its corresponding handset, such as by using a filter to block signals in a range near the frequency of the carrier signal associated with other handsets.  
         [0040]     While processing of calls comprising voice audio signals is described above, the approach described herein may as well be used to handle other types of audio signals. In such other cases, the frequency shift, carrier frequency, or other encoding parameter, as appropriate, is selected so as to ensure that the relevant system components can distinguish between and encoded signal and one that has not been encoded. As used herein, the term “encoding” means transforming the signal into a form so that system components may be configured to distinguish between the encoded signal and a signal that has not been encoded, such as by, without limitation, adjusting, modifying, or transforming the signal, combining the signal with another signal, using the signal to modulate another signal or carrier wave, etc.  
         [0041]     Although the foregoing invention has been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. It should be noted that there are many alternative ways of implementing both the process and apparatus of the present invention. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims.