Abstract:
A system whereby automatic dial-type recognition is employed to reduce the wait time for callers and prevent false identification of touch tone versus dial tone service. A system according to the present invention includes a control unit ( 103 ) located in a PBX ( 104 ) or other switch which detects whether a caller is placing a call using pulse or DTMF dialing. The control unit ( 103 ) in the PBX ( 104 ) generates a message during call setup which it provides to the remote system, such as an interactive voice response system.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to telecommunication systems, and in particular, to a communications system employing DTMF and pulse dialing. 
     2. Description of the Related Art 
     In modern interactive voice response (IVR) and voice mail systems, the preferred mechanism for user interaction from remote and sometimes local systems is via dual-tone multi-frequency (DTMF) recognition. However, in many parts of the world and even in North America, there remains a significant rotary or pulse dial base. 
     In order to accommodate both the installed DTMF and rotary dial bases, IVR systems provide an option for callers to either stay on the line (“if you have a rotary phone”) or to “press  1  now” (“if you have a Touch Tone phone”). Thus, current systems require the user to identify themselves, thereby tying up system resources while the system waits for the time-out that sends the rotary caller to a human operator. Touch tone callers must therefore go through a time-wasting step of listening to a message and pressing a digit just to identify themselves as touch tone callers. Rotary callers must often wait through an entire touch tone menu just to get service. Moreover, customer service companies often put elaborate menus in place to ensure that callers have tried an automated service before going to the more costly human service. Often, callers skip these menus by pretending to have rotary phones. While this is an advantage to the caller, the companies find that they have invested in a system but are receiving no benefits. 
     Accordingly, there is a need for a system for automatically identifying whether a caller has rotary or DTMF capabilities. There is a still further need for a system whereby line utilization is improved by removing a time-out condition from rotary callers. 
     SUMMARY OF THE INVENTION 
     These and other drawbacks in the prior art are overcome in large part by a system and method according to the present invention. More particularly, the present invention provides a system whereby automatic type recognition is employed to reduce the wait time for callers and prevent false identification of touch tone versus dial tone service. A system according to the present invention includes a control unit located in a PBX or other switch which detects whether a caller is placing a call using pulse or DTMF dialing. The control in the PBX generates a message during call setup which it provides to a remote system, such as an interactive voice response system. 
     More particularly, a control unit according to the present invention monitors whether a call request is received at a central switch using DTMF dialing or pulse dialing. Based on this determination, the control unit causes, for example, an ISDN controller to pack its setup word with the corresponding information. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A better understanding of the present invention is obtained when the following detailed description is considered in conjunction with the following drawings in which: 
     FIG. 1 is a block diagram illustrating a telephony system according to an embodiment of the present invention; 
     FIG. 2 is a block diagram illustrating in greater detail the telephony system of FIG. 1; 
     FIG. 3 is a diagram illustrating an ISDN setup information field according to an embodiment of the present invention; and 
     FIG. 4 is a flowchart illustrating operation of an embodiment of the present invention; 
     FIG. 5 is a flowchart illustrating operation of an aspect of the invention; and 
     FIG. 6 is a flowchart illustrating operation of another aspect of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning now to the drawings, and with particular attention to FIG. 1, a block diagram illustrating a telecommunication system  100  according to an embodiment of the present invention is shown. The telecommunication system  100  includes a central switch  104 , such as a private branch exchange (PBX) or a central office (CO). A plurality of telephones  102   a-   102   c  are coupled to the central switch  104 . The telephones  102   a-   102   c  may be either DTMF or pulse dialing telephones. It is noted that, while only three telephones  102   a-   102   c  are shown, in practice, a larger number may be provided. In addition, telephony devices, such as faxes, may also be coupled to the central switch  104 . Thus, FIG. 1 is exemplary only. The central switch  104  is configured to receive the DTMF or pulse signals and set up the corresponding telephone call with devices coupled in or to the public switched telephone network (PSTN) (or ISDN network)  105 . The central switch  104  includes a dialing interface  111  for receiving dial signals from the telephones  102   a-   102   c . The central switch  104  thus includes a standard DTMF receiver  110  and pulse receiver  112 . As will be discussed in greater detail below, a control unit  103  is configured to monitor the DTMF receiver  110  and the pulse receiver  112  and determine whether a request for call set up is being made. 
     For example, the control unit  103  may monitor output lines for activity. As will also be explained in greater detail below, the control unit  103  is further configured to send a command during the call set up identifying whether the caller is using a rotary or Touch Tone telephone, to the receiving device, which may be a private branch exchange (PBX)  106  including an interactive voice response (IVR) unit  108 . The PBX  106  includes a receiver  109 , which is configured to receive the signal from the control unit  103  of the central switch  104 . In response thereto, the IVR  108  either switches the caller to a human operator or to the automatic voice response system. The receiver  109  may be a known receiver configured to receive and decode ISDN signals. Additionally, the system may be coupled to an ISDN controller  113  for converting the resulting pulse code modulated signals into ISDN format for transmission to other devices such as the PBX  106 . 
     Turning now to FIG. 2, a diagram illustrating a central switch, illustrated as a PBX  104  according to an embodiment of the present invention is shown in greater detail. In particular, as discussed above, the central switch  104  includes a dialing interface  111 , which includes a DTMF dial receiver  110  and pulse receiver  112 . 
     As illustrated, the dialing interface  111  is embodied in a subscriber line interface circuit, or card (SLIC)  200 . The SLIC  200  performs the known BORSCHT functions of Battery feed, Over-voltage protection, Ringing, Supervision, Coding/Decoding, Hybrid and signal conditioning, and Test. Accordingly, the SLIC  200  includes a hybrid  202  and a codec  204 . The codec  204  may be a combined filter codec, or combocodec as are well known. The codec  204  is configured to perform known coding and decoding, including compression and decompression (such as μ law or a-law), of the audio signals. Other components of SLIC  200  are well known and not illustrated. 
     A control unit  103  is coupled to the SLIC  200 . The control unit  103  may be embodied as a microprocessor or microcontroller, or application specific integrated circuit. Finally, the control unit  103  may be configured to provide overall control of the central switch  104 , as well as DTMF/pulse identification according to the present invention, as will be discussed in greater detail below. 
     In particular, as will be described in greater detail below, the ISDN controller  113  is configured to receive a signal from the control unit  103  indicative of whether the incoming call received on the tip T and ring R lines is via a Touch Tone or pulse telephone. The ISDN controller  113  then packs its set up signal to the PBX  106  with data corresponding to the type of telephone making the call. 
     As is well known, the central switch  104  is able to respond to calls made using DTMF or pulse dialing. The control unit  103  is coupled to the DTMF and pulse dialing receivers  110 ,  112  and is configured to determine whether the incoming call has, in fact, been received using DTMF or pulse dialing. For example, the control unit  103  may monitor output lines. The control unit  103  then provides a signal to the receiving unit during call set up. 
     In particular, turning now to FIG. 3, a diagram illustrating an ISDN information field  300  according to the present invention is shown. As is well known, the ISDN information field  300  is a variable length field that contains the Q.931 protocol data used for the establishment maintenance and termination of network connections between two devices. The information field  300  includes a protocol discriminator field  302  which identifies the layer three protocol such as Q.931. In addition, a length field  304  is provided to indicate the length of the next field, the call reference value (CRV) field  306 . The call reference value field  306  is used to uniquely identify each call on user network interface. A message type field  308  is provided to identify the message type such as set up, connect, acknowledge, etc. The message type determines what additional information is required and/or allowed. Finally, a variable length information element field  310  is provided. The information element depends on the message type. According to the present invention, when the message type  308  is set to “set up”, a dial-type subfield  310   a  is provided in the information element field  310 . The dial-type field  310   a  identifies whether the call has been made using pulse or DTMF dialing. As will be discussed in greater detail below, during call set up the dial-type field  310   a  is read by the receiving PBX  106  and forwarded to the IVR  108 . In particular, as is well known, the receiver  109  may be a known ISDN receiver, which decodes the ISDN setup information, including the dial-type subfield. If the dial-type indicates that DTMF signalling has been employed, then the receiver  109  and the IVR  108  switch the call to the automatic IVR system. However, if the dial-type field  310   a  indicates that pulse dialing has been used, then the receiver  109  and the IVR  108  operate to switch the received call to a human operator. 
     Turning now to FIG. 4, a flowchart  400  illustrating operation of an embodiment of the present invention is shown. The flowchart  400  illustrates overall operation of the system at both the caller and terminator. In particular, in a step  402 , a caller using one of the telephones  102   a-   102   c  initiates a call. In response thereto, the central switch  104  detects the off-hook condition and receives the input telephone digits. The input digits are received by the dial interface  111 . Depending on whether the input digits have been made using DTMF signalling or pulse dialing, the DTMF detector  110  or the pulse detector  112  process the signals. In a step  404 , the control unit  103 , which has been monitoring the dial interface  111 , determines whether the call has been made using DTMF or pulse dialing. If the call has been made using pulse dialing, then in a step  406  the control unit  103  will instruct the ISDN interface  113  to make the appropriate indication in the dial-type field  310   a  of the information elements field  310  of the information field  300 . However, if the dial-type was detected as being DTMF, then the control unit  103  will instruct the ISDN interface  113  to make the corresponding alternate setting in the dial-type field  310   a  in a step  408 . In a step  410 , the ISDN interface  113  sends the call set up information field  300  to the receiving PBX  106 . As discussed above, the receiving PBX  106  includes an ISDN controller  109  which is configured to decode the received information field  300 . The PBX  106  then sets up the call with the IVR  108  and forwards to the IVR  108  whether the dial-type field  310   a  indicates DTMF or pulse dialing at the other end in a step  412 . In a step  414 , the IVR  108  processes the information of whether DTMF or pulse dialing has been used. In a step  416 , the IVR  108  connects the call to a human operator if pulse dialing has been employed and in a step  418  connects the caller to the IVR system if DTMF dialing has been used. 
     Turning now to FIG. 5, a flowchart illustrating operation of the transmitting central switch&#39;s  104  operation is shown according to an aspect of the present invention. In particular, in a step  502  a caller initiates a call which is received at the central switch  104 . The PBX receives the call request in a step  504  in a standard fashion, for example, via loop start detection. In a step  506 , the dialing interface  111  detects the dialing number. In a step  508 , the control unit  103  monitors the dialing interface  111  to determine whether the call has been received via the DTMF detector  110  or the pulse detector  112 . In a step  510 , the controller  103  makes the decision. If the DTMF detector  110  has been used, then in a step  514  the control unit  103  will cause the ISDN controller  113  to provide a first indicia in the dial-type field  310   a  of the information element field  310 . In a step  512 , however, the controller  103  will cause the ISDN interface  113  to provide second indicia in the dial-type field  310   a . In a step  516 , the encoder  204  will encode the audio signal received, such as by μ law or a-law encoding. Finally, in a step  518  the audio information packet is packed by the ISDN interface  113 . 
     Turning now to FIG. 6, a flowchart illustrating operation of the receiving PBX  106  is shown. In particular, in a step  602  the PBX  106  will receive the call request from the central switch  104 . In a step  604 , the PBX  106  control unit  109  will decode the received setup information. As is well known, the setup information includes the calling party and called party information. According to the present invention, the setup information further includes a dial-type code as discussed above. In a step  606 , the PBX will setup the connection to the IVR  108  or other telephony device. In a step  608 , the control unit  109  will, having decoded the setup packet  300 , provide the dial-type information to the IVR  108 . In a step  610 , the IVR  108  determines whether pulse or DTMF dialing has been employed. If pulse dialing has been employed, then in a step  612  the IVR will switch the received call to a human operator. In step  614 , if DTMF dialing has been employed, the IVR will activate its automatic interactive voice response mechanism. 
     The invention described in the above detailed description is not intended to be limited to the specific form set forth herein, but, on the contrary, is intended to cover such alternatives, modifications and equivalents as can reasonably be included within the spirit and scope of the appended claims.