Abstract:
A method and apparatus are provided for establishing a conference call connection among a plurality of conference call participants. The method includes the steps of providing a call pod for interconnecting a plurality of headsets of the plurality of participants, operably connecting a headset interface of a wireless telephone with a wireless telephone audio interface of the call pod and forming a two-way voice path among the plurality of headsets and the wireless telephone interface within the call pod.

Description:
FIELD OF THE INVENTION 
     The field of the invention relates to communication systems. More particularly, the field of the invention relates to conferenced telephone calls. 
     BACKGROUND OF THE INVENTION 
     The use of wireless telephones for communicating is well known. The use of wireless telephones for setting-up conference calls within the public switch telephone network (PSTN) is also known. 
     To form a conference call connection, a caller typically calls a PSTN operator and gives the operator a list of telephone numbers of participants to the conference call. The operator receives the telephone numbers and individually calls the participants. 
     To conference-in the participants, the operator invokes special features of a telephone switch within the PSTN. Within the switch, the call connection with each participant is typically divided into an incoming audio path (from a microphone of the participant) and an outbound audio path (to an audio speaker of the participant). To form a conference connection, the information on the inbound path of each participant must be summed with the information on the inbound paths of every other participant, and averaged. The summed and averaged information is then distributed to the participants on each outbound path. 
     While the conferencing features of the PSTN work well, they are sometimes difficult to access, set up and use. Further, where some of the participants are in a single location, the cost of a conference connection may not be justified. Accordingly, a need exists for a conferencing device that is easier to use and more amenable to use by local participants. 
     SUMMARY 
     A method and apparatus are provided for establishing a conference call connection among a plurality of conference call participants. The method includes the steps of providing a call pod for interconnecting a plurality of headsets of the plurality of participants, operably connecting a headset interface of a wireless telephone with a wireless audio interface of the call pod and forming a two-way voice path among the plurality of headsets and the wireless interface within the call pod. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a conferencing device in accordance with an illustrated embodiment of the invention; and 
     FIG. 2 is a schematic of the conferencing device of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 depicts a call pod  10 , shown generally under an illustrate embodiment of the invention and in a context of use. As shown, a wireless telephone (e.g., cellphone, cordless telephone, PCS telephone, digital cellular, TDMA, CDMA, GSM, etc.)  12  may be coupled to the call pod  10  by use of an interconnecting cable  28  disposed between a headset receptacle  30  of the wireless phone  12  and wireless audio interface receptacle  18  of the call pod  10 . Similarly, a number of headsets  14 ,  16  may be connected to the pod  10  by connecting a headset plug  32 ,  34  into headset receptacle  20 ,  22 ,  24 ,  26 . Each headset  14 ,  16  may be of the “hands-free” variety consisting of an earphone part and a microphone part. 
     The call pod  10  allows several persons on one side of a conversation to listen and speak without using a “speakerphone”. The use of the call pod  10  overcomes the annoying speakerphone characteristic that one participant may begin to speak at the same time the party at the other end of the conversation is speaking. This causes one party not to be heard by the other, because the speakerphone is a simplex device that must switch from receive to transmit when the local party begins to speak. In contrast to a speakerphone, the call pod  10  allows duplex operation, even when several persons at the local end and far end wish to speak simultaneously. 
     While only two headsets  14 ,  16  are shown in FIG. 1, it is to be understood that any number of headsets  14 ,  16  may be used with the call pod  10 . It is also to be understood that as used herein, a “call pod” is a portable telephone device which forms conference calls among a plurality of call participants, at least two of which are proximate the call pod  10 . 
     FIG. 2 is a schematic of the pod  10 . Shown in the schematic are plug receptacles CON 1 , CON 2 , CON 3  and CON 4  which correspond to the headset receptacles  20 ,  22 ,  24 ,  26  of FIG. 1, respectively. Also shown in FIG. 2 is plug receptacle CON 5  which corresponds to the wireless telephone audio interface  18  of FIG.  1 . 
     Under the illustrated embodiment, the call pod  10  relies upon four circuits  50 ,  52 ,  54 ,  56  to facilitate conferencing functions. The first circuit may be a sense circuit  50  structured to automatically activate the call pod  10  during use and deactivate the call pod  10  when not in use. The second circuit may be a flasher circuit  52  which works in conjunction with the sense circuit  50 . The flasher circuit  52  may be a free-running multivibrator that sequentially activates and deactivates a light emitting diode LED 1   28  at an appropriate cycling rate (e.g., one-half second). 
     The sense circuit  50  may operate by monitoring a microphone bias current on a microphone input # 2  of the wireless telephone audio interface CON 5 . The bias current provided by the wireless telephone  12  may be used to activate the call pod  10  during a call, thereby eliminating the need for a power switch that a local party would manually operate each time a call was received or placed. It should be noted that the bias current from the wireless telephone  12  is only present during the time a call is in progress. 
     Furthermore, it is possible that the voltage providing the bias current could be either positive or negative, depending upon the design of the wireless telephone  12 . Diodes D 1 , D 2  and transistors Q 9  and Q 10  provide a bias current detector and a control signal path to a power switch (e.g., transistor Q 8 ), such that a bias current of either polarity causes transistor Q 8  to conduct. Conduction of transistor Q 8  activates the call pod  10 . 
     The third and fourth circuits  54 ,  56  function to form the conferencing audio signal. The third circuit  54  senses a microphone input from each headset through a set of summing resistors R 1 , R 2 , R 3 , R 4 . Since the microphone parts of the headsets  14 ,  16  require a bias current, resistor R 5  is provided as a source of such current. 
     The summed output from the microphones may be capacitively coupled through capacitor C 1  into an opamp IQ 8 . IQ 8  may be a conventional audio quality amplifier connected as a summing amplifier. Within the opamp IQ 8 , the summed microphone signal is amplified by an appropriate amplification factor (e.g.,  10 ) and applied through a limiting resistor R 32  to the microphone input # 2  of the wireless telephone audio interface CON 5 . 
     Within the wireless telephone  12 , a portion of the summed output from the third circuit  54  is added to a wireless telephone audio output signal and provided as feedback. The wireless telephone output (i.e., the conference output) is provided on output connection # 3  of the wireless telephone audio interface CON 5 . 
     The wireless telephone output on pin # 3  of the wireless telephone audio interface CON 5  is amplified by transistor Q 5  and provided as an input to balancing resistors R 14 , R 15 , R 16 , R 17 . The balancing resistors R 14 , R 15 , R 16 , R 17  in turn drive respective earphone transistors Q 1 , Q 2 , Q 3 , Q 4 . The respective earphone transistors Q 1 , Q 2 , Q 3 , Q 4 , in turn, drive the respective earphones of the headsets  14 ,  16 . Since the audio paths of the third and fourth circuits  54 ,  56  are not switched in any way, the duplex operation of the telephone circuit is preserved. 
     Under the illustrated embodiment, a number of local users may participate (using headsets  14 ,  16 ) in a conference call with a remote participant (not shown). The remote participant may be contacted through the wireless telephone  12  using conventional techniques. 
     Further, a local user may participate actively, or simply monitor the conversation. For example, if a user of a headset (e.g.,  14 ) should want to passively monitor the call, then the user may activate a MUTE button  42 . Activation of a MUTE button  38 ,  40 ,  42 ,  44  functions to disconnect a local user microphone of a headset  14 ,  16 . 
     Further, a MUTE button  36  may also be provided for use with the remote participant. Muting the remote participant allows the local users to participate in a local conference without being heard by the remote participant. 
     The use of the call pod  10  offers other advantages not possible under prior art devices. For example, a number of local users can participate in a conference call in a public location without a complete loss of confidentiality. By using the headsets  14 ,  16 , it is not likely that an eavesdropper could hear each local user. Even if the eavesdropper could hear all of the local users, the eavesdropper would still be unable to hear the contributions of the remote participant. As such, the call pod  10  functions to provide a high degree of confidentiality even in public places. 
     A specific embodiment of a method and apparatus for providing portable conference capabilities has been described for the purpose of illustrating the manner in which the invention is made and used. It should be understood that the implementation of other variations and modifications of the invention and its various aspects will be apparent to one skilled in the art, and that the invention is not limited by the specific embodiments described. Therefore, it is contemplated to cover the present invention and any and all modifications, variations, or equivalents that fall within the true spirit and scope of the basic underlying principles disclosed and claimed herein.