text: for clarity and simplicity , the present specification shall refer to structural and / or functional network elements , entities and / or facilities , relevant communications standards , protocols and / or services , and other components that are commonly known in the telecommunications art without further detailed explanation as to their configuration or operation except to the extent they have been modified or altered in accordance with and / or to accommodate the preferred embodiment ( s ) presented . with reference to fig2 , an exemplary telecommunications system is illustrated in accordance with a preferred embodiment . the operation of the system shall be described by way of an exemplary ip call initiated from calling cpe 60 to called cpe 90 . for illustrative purposes , cpe 60 and 90 are shown as ip telephones , e . g ., involved in a voip call . however , it is to be appreciated that the cpe 60 and 90 may be any appropriate type of cpe as is known in the art for conducting various types of ip or packet - switch calls , e . g ., voice , data , multimedia , etc . further , it is to be appreciated that while only one particular call between a pair of cpe ( i . e ., the calling and called cpe 60 and 90 ) is shown , a plurality of such calls are similarly being handled simultaneously between a plurality of likewise situated calling and called cpe . as shown , the cpe 60 and 90 are operatively connected to an ip network 62 , or another like packet - switched network , so that end users employing the same may exchange communications with one another . an ip gateway 64 bridges the ip network 62 with the pstn 70 . that is to say , the ip gateway 64 acts as a point of entry for packet - switched calls from the ip network 62 headed into the pstn 70 , and similarly acts as a point of entry for circuit - switched calls from the pstn 70 headed into the ip network 62 . in the usual manner , the ip gateway 64 selectively converts and / or translates packet - switched calls into circuit - switched calls and vice versa depending on the direction of traffic flow . suitably , a class 5 switch 72 , or other suitable circuit - switched telecommunications switch , on the pstn side of the ip gateway 64 interfaces with the ip gateway 64 , e . g ., via a gr - 303 interface 74 , or another like interface such as a v . 5 . 2 interface . use of the gr - 303 interface 74 , the v . 5 . 2 interface or the like , is advantageous insomuch as from the perspective of the switch 72 the ip gateway 64 acts and / or otherwise appears as a remote digital terminal ( rdt ) while continuing to appear from the ip side as a gateway into the pstn 70 . the switch 72 is responsible for call routing and optionally provides other call processing and / or call features normally associated therewith . for example , when a call is placed from the calling cpe 60 , the call is routed over the ip network 62 to the ip gateway 64 where it is translated from a packet - switched call to a circuit - switched call . the call then enters the pstn 70 via the switch 72 ( which may be considered part of the pstn 70 ). this represents a first leg of the complete call or an originating half - call ( indicated by the combination solid / dashed arrow 80 ). the switch 72 then routes the call to the intended recipient . accordingly , in this example , the call is routed , again via the gr - 303 interface 74 , back to the ip gateway 64 where the circuit - switched call is translated back into a packet - switched call . finally , the call is directed over the ip network 62 to the cpe 90 . this represents a second leg of the complete call or a terminating half - call ( indicated by the combination solid / dashed arrow 82 ) that along with the associated originating half - call 80 completes the connection between the cpe 60 and 90 . suitably , the ip gateway 64 includes an audio watermark ( awm ) generator 66 and an awm sensor 68 . the awm generator 66 operates on half - calls passing through the gateway 64 from the ip network 62 to the pstn 70 , e . g ., in this case the first or originating half - call 80 , and the awm sensor 68 operates on half - calls passing through the gateway 64 from the pstn 70 to the ip network 62 , e . g ., in this case the second or terminating half - call 82 . more specifically , when the originating half - call 80 reaches the gateway 64 , the awm generator 66 generates and applies an awm thereto that uniquely identifies the originating half - call 80 . suitably , the awm is an encoded signal , e . g ., superimposed on the traffic of the originating half - call 80 , that is substantially unperceivable by and / or inaudible to end users employing the cpe 60 and / or 90 , but nevertheless detectable . for example , a suitable awm may be achieved by encoding a low frequency , low intensity signal with some unique identifying data or low bit rate information . however , other suitable types of substantially hidden audio watermarking techniques as may be known in the art are also contemplated . when the terminating half - call 82 reaches the gateway 64 , the awm sensor 68 analyzes and / or examines the same to detect the accompanying awm . accordingly , the terminating half - call 82 is recognized as corresponding to the originating half - call 80 . of course , it is to be appreciated that a plurality of various originating and terminating half - calls are likely being routed through the gateway 64 at any given time . for example , a call may be made from cpe ( situated similar to cpe 60 ) to cpe 76 , e . g ., a regular or non - ip telephone , that is connected to the pstn 70 . accordingly , the originating half - call from the ip network 62 passes through the ip gateway 64 , but there is no corresponding terminating half - call that passes through ip gateway 64 , rather the corresponding terminating half - call is routed over the pstn 70 to the cpe 76 . likewise , for a call originating from the cpe 76 to cpe situated similar to cpe 90 , the ip gateway 64 has a terminating half - call passing therethrough with no corresponding originating half - call passing therethrough . furthermore , there may be numerous distinct calls having both their originating and terminating halves passing through the gateway 64 . nevertheless , the audio watermarking provides a way to distinguish the identity of originating and terminating half - calls passing through the gateway 64 that correspond to and / or are otherwise associated with one another . suitably , once the half - calls 80 and 82 are recognized as corresponding to one another , the solid arrow or packet - switched portions of the half - calls 80 and 82 are directly connected to one another . in essence , the pstn 70 is bypassed by short circuiting the call at the ip gateway 64 . accordingly , the switch 72 is no longer involved in the call once the connection is completed . that is to say , the call routing path represented by the dashed arrow or circuit - switched portions of the half - calls 80 and 82 is no longer employed so as to relieve the switch 72 of having to support the call for its entire duration . additionally , the load on the ip gateway is also lessened insomuch as the packet - switched portion of the first half - call 80 is connected directly with the packet - switched portion of the second half - call 82 . that is to say , once the connection is completed , the ip gateway 64 no longer has to convert or translate the originating half - call 80 from a packet - switched call to a circuit - switched call , nor convert or translate the terminating half - call 82 back from a circuit - switched call to a packet - switched call . in fact , having connected the packet - switched portions of the half - calls 80 and 82 directly with one another , the ip gateway 64 is also optionally released from the call entirely , i . e ., the call is optionally connected between the cpe 60 and cpe 90 over the ip network 62 without passing through the gateway 64 . for example , one or both of the cpe involved in the call are optionally provided with the other &# 39 ; s ip address , or the like , so that they may connect directly with one another over the ip network 62 ( i . e ., without passing through the gateway 64 ). with reference to fig3 , an exemplary process for handling originating half - calls within the ip gateway 64 is illustrated . at step 100 , the gateway 64 receives an originating half - call from the ip network 62 . at step 102 , the received originating half - call is converted or translated into a circuit - switched call . at step 104 , a uniquely identifying awm is applied to the received half - call , e . g ., via the awm generator 66 , and information or data corresponding to the applied awm is stored , e . g ., in an awm database ( db ) 69 ( see fig2 ). suitably , the awm db 69 relates each particular applied awm to the respective half - call it identifies . at step 106 , the audio watermarked half - call is directed to a circuit - switched telecommunications switch ( e . g ., the switch 72 ) for routing . with reference to fig4 , an exemplary process for handling terminating half - calls within the ip gateway 64 is illustrated . at step 200 , the gateway 64 receives a terminating half - call from the pstn 70 , e . g ., via switch 72 . at step 202 , the received terminating half - call is analyzed and / or examined to detect and / or identify any accompanying awm , e . g ., via the awm sensor 68 . at step 204 , the received half - call is converted or translated into a packet - switched call . at decision step 206 , it is determined if the detected awm ( if any ) from the received half - call matches a previously applied awm . suitably , if an awm is detected , it is compared against those stored in the awm db 69 to determine if a match exists and / or to identify the other half - call to which the particular awm was applied . if no match exists ( including , if no awm was detected ), then the process continues to step 208 where the received terminating half - call is directed over the of the ip network 62 to the called cpe . on the other hand , if a match does exist , then a corresponding pair of half - calls has been recognized and the process continues to step 210 where the received terminating half - call is connected to the identified originating half - call having the matching awm . thereafter , the process continues to step 208 such that the identified originating half - call is connected over the ip network 62 to the called cpe ( e . g ., as represented by the solid arrow portions of half - calls 80 and 82 ). with regard to fig2 and 4 , the application and detection of the awm is shown and described above as occurring while the respective half - calls are in their circuit - switched states . however , the application and detection of the awm is optionally carried out in a similar manner while the respective half - calls are in their packet - switched states . for example , steps 102 and 104 may be transposed and steps 202 and 204 may be transposed . for simplicity and clarity , only a single switch 72 and a single gateway 64 have been shown in fig2 and described above . it is to be appreciated , however , that a plurality of similarly situated network elements operating in like manner optionally exist within the system . moreover , for some calls , the originating and terminating half - calls may be routed through different switches and / or gateways . for example , an originating half - call from a calling cpe may be directed over the ip network 62 to an originating gateway and on to an originating switch . however , due to the call &# 39 ; s destination , it may then be routed over the pstn 70 to a terminating switch ( different than the originating switch ) which directs a terminating half - call to a terminating ip gateway ( also different than the originating gateway ), and then over the ip network 62 to the called cpe . suitably , in such instances , the originating gateway communicates to the terminating gateway the awms applied by the originating gateway and information regarding the half - calls they identify so that the terminating gateway upon detecting an awm in a terminating half - call is able to establish the identity of the terminating half - call &# 39 ; s corresponding originating half - call . for example , the awm db 69 is optionally maintained on a db server or the like connected to the ip network 62 so as to be accessible to all the ip gateways in the system . accordingly , the relevant information and / or data regarding any awm applied by any originating gateway is stored therein so as to be accessible by any terminating gateway that detects an awm . accordingly , a corresponding originating and terminating half - call pair is recognizable regardless of whether or nor they are passing through the same gateway . suitably , once they are so recognized , they are directly connected to one another within the ip network 62 thereby bypassing the pstn 70 entirely and optionally bypassing one or both of the originating and terminating gateways . it is to be appreciated that in connection with the particular exemplary embodiments presented herein certain structural and / or function features are described as being incorporated in defined elements and / or components . however , it is contemplated that these features may , to the same or similar benefit , also likewise be incorporated in other elements and / or components where appropriate . it is also to be appreciated that different aspects of the exemplary embodiments may be selectively employed as appropriate to achieve other alternate embodiments suited for desired applications , the other alternate embodiments thereby realizing the respective advantages of the aspects incorporated therein . it is also to be appreciated that particular elements or components described herein may have their functionality suitably implemented via hardware , software , firmware or a combination thereof . additionally , it is to be appreciated that certain elements described herein as incorporated together may under suitable circumstances be stand - alone elements or otherwise divided . similarly , a plurality of particular functions described as being carried out by one particular element may be carried out by a plurality of distinct elements acting independently to carry out individual functions , or certain individual functions may be split - up and carried out by a plurality of distinct elements acting in concert . alternately , some elements or components otherwise described and / or shown herein as distinct from one another may be physically or functionally combined where appropriate . in short , the present specification has been set forth with reference to preferred embodiments . obviously , modifications and alterations will occur to others upon reading and understanding the present specification . it is intended that the invention be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof .