referring now to the accompanying drawings , fig1 illustrates a general system overview of a call forwarding system in accordance with an embodiment of the present invention . according to the call forwarding system , a calling party 10 attempts to contact a destination or customer 30 who has changed telephone numbers . in the example illustrated in fig1 , originally the customer &# 39 ; s telephone number was ( 314 ) 227 – 1234 , but it has been changed to ( 314 ) 849 – 1234 . in the case when the calling party 10 has not been advised of the new telephone number , the calling party 10 dials the old , disconnected telephone number 14 of the customer 30 which causes the calling party &# 39 ; s central office 12 to establish a connection with the central office of the dialed telephone number 16 . the central office 16 determines that the dialed telephone number 14 has been disconnected and forwards the call to a hub 18 which is designated to handle disconnected telephone numbers . the hub 18 then generates a trigger causing processing to occur within an advanced intelligent network ( ain ) platform including an integrated services control point ( iscp ) 20 . the iscp 20 queries a line information for open networks ( lion ) database 22 to determine whether the disconnected number 14 is eligible for call forwarding , whether the customer 30 has paid to have calls forwarded to the new telephone number and what the new telephone number is . if it is determined that the destination 30 has paid for call forwarding , and the disconnected number 14 is eligible for call forwarding , an announcement is played informing the calling party 10 of the new telephone number and stating that the destination 30 has paid to forward the call automatically . subsequently , the call is forwarded from the hub 18 to the new telephone number &# 39 ; s central office 26 which rings the new telephone number 30 . however , if the destination 30 has not paid for call forwarding , but the disconnected number 14 is eligible for call forwarding , the iscp 20 queries a line information database ( lidb ) 24 to determine whether the calling party 10 is eligible to pay to forward the call . if the calling party 10 is eligible , the iscp 20 plays an announcement to the calling party 10 informing the calling party 10 of the new telephone number and asking the calling party 10 if the calling party 10 would like to pay to have the call forwarded to the new number . if the calling party 10 does not want the call forwarded , the calling party 10 hangs up and the call terminates without being forwarded . if the lidb query indicated that the calling party 10 is not eligible for call forwarding , the call is directed to standard intercept processing . if the calling party 10 is eligible and would like the call forwarded , the call is forwarded to the new telephone number 30 in the same manner that the call is forwarded to the new telephone 30 when the customer 30 has paid for the forwarding . thus , the call forwarding system of the present invention forwards a call from a telephone number that has been disconnected to the new telephone number if someone is willing to pay for the call forwarding . moreover , the call forwarding system determines whether the customer ( subscriber ) has elected to pay for the call forwarding or whether the calling party has elected to pay for the call forwarding . according to a preferred embodiment , call forwarding only occurs if the old telephone number and new telephone number are both served by the same telephone company and the new telephone number is within the local calling scope of the old telephone number . new telephone numbers not meeting these requirement are not translated in the central office of the dialed telephone number and are not routed to the hub . when the old telephone number is changed , if the new telephone number satisfies these requirements , the switch of the old telephone number is informed so that a trigger will occur on the old telephone number . according to a preferred embodiment , the calling party pays option is available on a per call basis to calling parties who are customers of the telephone company serving the old telephone number . moreover , calling parties with certain services and equipment are not eligible to pay for forwarding calls , e . g ., calling parties using hotel telephones . any call excluded from utilizing the call forwarding system of the present invention can be provided with standard switch based intercept treatment . consequently , the current standard intercept trunk group and routing scheme remain in place throughout the network but will see some reduced usage . most advanced intelligent network ( ain ) switch types may be used to implement the call forwarding system of the present invention . each switch must have ss7 capability for communicating with an integrated services control point ( iscp ), and must be able to prefix a unique ( 0xx ) three digit code to interface with a dms hub . examples of switches are the lucent technologies 1aess , the lucent technologies 5ess , the northern telecom ( nortel ) dms - 100 , and the ericsson axe switch . preferably , the hub 18 is a dms central office switch ; however , any other switch with the ability to provide the recorded announcement capability ( voicing back the digits of the new telephone number ) may be used alternatively . by using designated hub locations , it becomes unnecessary to establish triggers for each intercepted telephone number within a telephone company &# 39 ; s network . thus , all eligible intercepted calls are routed to designated hub locations where the trigger occurs . the dms switch 18 acts as the trigger hub for the call forwarding system of the present invention . in other words , all eligible calls to the telephone numbers which have been changed are intercepted at the old telephone number &# 39 ; s switch 16 and rerouted to the dms hub 18 for triggering . when the calling party uses the call forwarding system of the present invention and completes the call via the dms switch ( hub ) 18 , all legs of the call are held for the duration of the call . in particular , the call will hold a trunk from central office 12 to central office 16 , a trunk from central office 16 to central office 18 , and a trunk from central office 18 to central office 26 for the duration of the call . in contrast , according to prior systems , a customer encountering the intercepted number would have redialed the call from central office 12 directly to central office 26 holding only one trunk for the duration of the call . as a result of the call processing required to implement the present invention and the announcement treatment for each intercepted call at the dms hub 18 , the calling party &# 39 ; s hold time increases by 25 to 30 seconds for each call to a disconnected telephone number 14 . however , the advantages of the present invention outweigh the increased hold time . rerouting the call to the dms hub 18 requires using a non - switch numbering plan area ( npa ) code , such as 0xx . this three digit code routing index prefix should be standardized throughout the telephone company &# 39 ; s network to minimize the number of call processing records ( cprs ) required within the iscp 20 . preferably , the same 0xx code is used throughout multiple market areas , i . e ., standardized across the telephone company &# 39 ; s network . however , multiple 0xx codes need to be assigned when two or more npa codes reside within the same switch . for example , if the calling party 10 dials ( 314 ) 227 – 1234 ( the called party number ( cdn )), the intercepting switch 16 prefixes the 0xx code ( e . g ., 022 ) resulting in 022 227 – 1234 being forwarded to the dms hub 18 . in other words , 314 is not forwarded , rather , the logic within the cpr recreates the original npa 314 using the signaling point code ( spc ), which identifies the switch that forwarded the digits , and 0xx code . the line identification for open networks ( lion ) database 22 is a database application available from nortel . tcp / ip queries into the lion database occur when implementing the present invention . a line information database ( lidb ) 24 , available from bell communications research , inc . of livingston , n . j ., is also provided . tcp / ip queries into the lidb database are utilized for the call forwarding system of the present invention . according to a preferred embodiment , answer supervision does not occur until the new telephone number 30 answers the call . thus , any toll charges applicable from the calling party 10 to the intercepted number 14 are charged to the calling party if and only if the call is answered at the new station 30 . referring now to fig2 and fig3 , a simplified flow of the logic for the call forwarding system of the present invention , and an exemplary relationship between call forwarding components are illustrated . first , at step s 10 the calling party 10 calls the disconnected telephone number 14 causing the called number with a three digit routing index prefix to be routed to the dms hub 18 . the three digit routing index then causes a public office dialing plan ( podp ) trigger to occur on the three digits and a three digit podp cpr 32 executes . the podp trigger is an ain trigger created in an office as opposed to a trigger on a telephone line . the three digit podp cpr 32 executes whenever the three digit podp trigger is encountered at the dms hub switch 18 . this cpr 32 determines the new telephone number , and who will pay for the forwarding . if the calling party pays , the cpr 32 also determines whether the calling party is billable by the telephone company . if the logic at any point determines that the call may not be handled by the call forwarding system of the present invention , the call is directed to the existing intercept system for standard switch based processing . otherwise , the cpr 32 directs commencement of announcements which inform the calling party of the new telephone number , and the cpr 32 may direct the call to be forwarded to the new telephone number 30 , depending upon the designated sponsor of the service ( subscriber or caller ) and whether the calling party 10 remains on the line . thus , at step s 10 , a podp trigger cpr 32 commences execution after the dms hub 18 receives the phone number prefixed with the three digit routing index . at step s 11 , the logic first maps the three digit routing index prefix to the dialed npa based upon the prefix sent from the switch 16 and the spc of the originating switch 16 . the npa is found in a stand alone npa table 34 preferably , but not necessarily located within the iscp 20 . the keys into this table 34 are the three digit routing index prefix and the spc , and the data retrieved is the npa associated with the dialed number . when the npa associated with the three digit routing index prefix is successfully found , at step s 12 a query is launched to the lion database 22 via the generic data interface ( gdi ) over tcp / ip using a get data query , which is described below . the key into the lion database 22 is the originally called number ( cdn ), which is reconstructed to ten digits with the npa found in the npa table 34 as described above . the result of this query , if successful , contains two data elements : the new 10 - digit telephone number and an icc code . the icc code designates three things : whether call forwarding is paid for by the subscriber or the caller ; the class of service ( for example , business or residence ) of the intercepted number , if the subscriber is paying ; and the designated language ( e . g ., english or spanish ) of any announcement to be played , if the subscriber is paying . if the lion query is determined to be unsuccessful at step s 14 , the call is handled by the standard intercept system at step s 30 . otherwise , if the query is successful , at step s 16 it is determined whether the result of the query to the lion database 22 indicates that the subscriber is paying for call forwarding . if it is determined that the subscriber pays , at step s 17 an announcement is played informing the calling party of the new number , and the fact that the destination has paid to automatically forward the call . the message varies in language based upon the icc code returned by the lion database 22 . subsequently , at step s 26 the call is completed to the new telephone number . if the lion database query indicates that the calling party is paying , at step s 18 it is determined whether the caller &# 39 ; s npanxx is an npanxx serviced by the telephone company . a look up in a cpn table 36 which includes all npanxxs served by a telephone company can be used to determine whether the caller &# 39 ; s particular npanxx is serviced by the telephone company . the cpn table 36 is preferably , but not necessarily , stored within the iscp 20 . if the calling party &# 39 ; s npanxx is found in the cpn table 36 , i . e ., the cpn is within the subscriber &# 39 ; s telephone company network , at step s 20 a query is launched to the lidb 24 . however , if at step s 18 it is determined that the calling party &# 39 ; s npanxx is not within the cpn table 36 , the call is handled by the standard intercept system at step s 30 . the primary purpose of the lidb query is to determine whether the telephone company is able to bill the calling party for the call forwarding . thus , the query retrieves the type of service and equipment ( s / e ) of the calling party from the lidb 24 . in other words , an s / e field is retrieved from lidb 24 using the calling party &# 39 ; s number as the access key . the retrieved s / e field designates the type of service and equipment of the calling party , for example , pay phone , residence line , hotel , etc . only specific s / e codes are billable and therefore only the calling parties having the billable s / e codes are allowed to be offered the option of paying for call forwarding . billable codes are stored in a s / e table 38 , preferably but not necessarily residing within the iscp 20 . according to a preferred embodiment , only calling parties with plain old telephone service ( pots ), business and residence lines can be billed . in other words , only s / e codes representing pots business and residence lines appear in the s / e table 38 . thus , centrex lines , prison telephones , coin telephones , hotel / motel telephones etc . cannot be billed and are not eligible for calling party pays option . of course , it is the telephone company which determines which types of lines can be billed and the above represents only one example of billable s / e . if the query to the lidb 24 is determined to be unsuccessful at step s 22 , the call is routed to the standard intercept system at step s 30 for standard processing . however , if the query is successful , at step s 24 it is determined whether the cpn &# 39 ; s s / e code is in the s / e table 38 ( i . e ., is billable ). if the cpn &# 39 ; s s / e code is not within the s / e table 38 , the call is routed to the standard intercept system at step s 30 and no offer for call forwarding is presented to the caller . if the caller &# 39 ; s s / e code is determined to be billable at step s 24 , the calling party is offered the option to have the call forwarded to the new telephone number at step s 25 . another element which may be returned from the lidb query , at step s 20 , is a language indicator . if a calling party is determined to be a spanish speaking customer , the announcement may be played in spanish and this field is populated with a value of one . otherwise , the announcements are played in english . it is possible for the customer to dictate the result of the language query at the time the telephone number is changed . at step s 25 a series of announcements is played to the caller . these announcements vary in language , based upon the value of the language indicator returned from the lidb 24 . it is preferable that the announcements direct the calling party to hang up to avoid being charged for the call forwarding . if , and only if , the caller stays on the line throughout the announcements , at step s 26 the call is completed to the new telephone number which was found in the lion database 22 . if the caller hangs up at any time during the series of announcements , the caller is not billed for call completion . in summary , the three digit podp cpr 32 facilitates call completion of intercepted calls when the new telephone number is known , and when either the subscriber has paid to have the calls completed , or the caller is billable by the telephone company and chooses to pay for the call forwarding by remaining on the line . an ain call unit ( acu ) measurement cpr 40 may also be provided to record service measurements and perform data sampling for error conditions . the service measurements measure how much of the iscp &# 39 ; s cpu resources are being used in terms of ain call units ( acu &# 39 ; s ). this cpr 40 is separate from the trigger cpr ( s ) because of the iscp limitation on the number of overall service measurement vectors available . the acu cpr 40 is called by the three digit podp cpr 32 . the npa table 34 is a stand alone table used by the three digit podp cpr 32 to determine the npa and “ normal ” intercept route index associated with the three digit routing index prefix and the spc of the incoming query . because the full 10 - digit cdn is not sent in the tcap message to the cpr , the npa table 34 is necessary to determine the npa of the cdn so that the full 10 - digit cdn may be used to perform the query to the lion database 22 . the npa table 34 utilizes the prefix ( three digit ) and the spc of the querying switch as the keys into the table , and the associated npa and the intercept route index are returned . in summary , the prefix table 34 exists only once in each iscp 20 and converts the three digit prefix to an npa . the s / e table 38 is used by the three digit podp cpr 32 to check whether the service / equipment indicator returned from lidb 24 is a valid , billable number . only when the s / e indicator corresponding to the cpn is found in the s / e table 38 is the intercepted call allowed to complete to the new telephone number 30 . the service / equipment table contains an integer value , which is the s / e indicator , as the key . the service / equipment table exists only once in each iscp and contains only a single column listing all valid s / e values . the cpn table 36 is used by the three digit podp cpr 32 to ensure that queries to the lidb 24 for a given cpn are launched only if the cpn &# 39 ; s npanxx is supported in the telephone company &# 39 ; s lidb . without this prescreening , the query could get lost or rejected by the ss7 network . furthermore , without this prescreening , the phone company may have access to the lidb of another phone company without the ability to bill the other phone company &# 39 ; s customers for the forwarding of the call . in another embodiment , a gdi map table ( not shown ) is provided between the three digit podp cpr 32 and the lion 22 and also between the three digit podp cpr 32 and the lidb 24 . the gdi map table is used by the three digit podp cpr 32 to format and perform the query to external databases such as the lion 22 and lidb 24 databases . in other words , the gdi map table translates information from the three digit podp cpr 32 format into the external databases &# 39 ; formats . according to a preferred embodiment , logic error handling may be provided . according to this preferred embodiment , if an improper code is received by the iscp 20 from the lion 22 , an error message containing the called party number is provided to facilitate investigation . this logic error handling occurs when either the cdn is not eligible for call forwarding or the code returned from the lion database 22 is incorrect . get data messages are used to query external systems such as the lion database 22 and lidb 24 . the get data message generally includes a transmission id number unique to the get data query for identifying the get data query and a 10 - digit telephone number , for example , the old telephone number 14 . the return result from the get data query typically includes the same transmission id associated with the get data query , a field indicating whether or not the query was successful , a field indicating the icc option , i . e ., who is paying for the forwarding , the language a message should be played in , whether or not the line is a business line or residence line , and the new 10 - digit telephone number . table 1 below illustrates exemplary icc codes returned from the lion database 22 . some dms hubs 18 do not operate properly when an intra switch intercept is required . an example of an intra switch intercept is when the calling party 10 is calling a disconnected number 14 having a central office which also operates as the hub . a solution to the intra switch problem is to route all dms intra switch intercepted calls to another dms hub location 18 . the solution increases the availability of the call forwarding system of the present invention in the dms switch , however , it adds to the network load between the two switches . thus , calls received on switches which also operate as hubs are treated in the same manner as intercepted numbers in switches not acting as hubs . that is , the intercepted number is assigned a 0xx code and the call is routed to a dms hub over an ss7 trunk . an exemplary message flow between various components of the call forwarding system of the present invention are now described with reference to fig4 , 5 , and 6 . referring to fig4 , initially the calling party 10 enters the digits of the party being called , which are collected by the central office 12 . the call is then routed to central office 16 , where it is determined that the called number is a forwardable disconnected number , and the 7 - digit number is assigned a 0xx code which is prefixed to the collected digits , and routes the call to the dms hub 18 . the prefix causes an ain trigger to be sent from the dms hub 18 with the called party number , including the prefix , and the calling party number . the iscp 20 then determines the correct npa of the 7 - digit dialed number by querying the npa table 34 . the icc code and new telephone number is then determined from the lion database 22 via a get data query . the lion database 22 returns the 10 - digit telephone number of the new telephone number 30 and an icc code of 74 , indicating the icc service type of calling party pays , as seen in table 1 . if the npanxx of the calling party is found in the cpn table 36 , the calling party is determined to be a customer of the telephone company , and the iscp 20 then queries the lidb 24 to determine if the calling party 10 is a billable station . the query returns the service / equipment indicator . in the example shown in fig4 , the lidb 24 determines the calling party 10 is a number which can be billed for call completion ( due to the s / e table lookup ). thus , the iscp 20 plays a message which includes the new telephone number and asks the calling party whether it would like the call forwarded for a fee . if the calling party remains on the line throughout the message , the call is forwarded to the new telephone number 30 and the calling party 10 is billed accordingly . therefore , the iscp 20 sends the new telephone number to the switch , tells the switch to forward the call , and sends appropriate automated message accounting ( ama ) modules to the switch for the switch to perform billing in a known manner . when the call is answered at the new telephone number 30 , the billing begins . the example shown in fig5 is similar to the example shown in fig4 except in fig5 , the results from the lidb query indicate that the calling party 10 cannot be billed for call completion . therefore , the call is routed to a standard intercept service and processed accordingly . in the example shown in fig6 , the lion query returns an icc code with a value of 72 or 73 which indicates that the service type is subscriber pays , as shown in table 1 . therefore , no query to lidb 24 is necessary . thus , the announcement is immediately played and the call is forwarded to the new telephone number 30 . while the invention has been described with reference to several exemplary embodiments , it is understood that the words which have been used are words of description and illustration , rather than words of limitation . changes may be made , within the purview of the appended claims , as presently stated and as amended , without departing from the scope and spirit of the invention in its aspects . although the invention has been described with reference to particular means , materials and embodiments , the invention is not intended to be limited to the particulars disclosed ; rather , the invention extends to all functionally equivalent structures , methods and uses , such as are within the scope of the appended claims . for example , although the call forwarding system of the present invention has been described with reference to automatically forwarding the call to the new telephone number 30 , a dual tone multi - frequency ( dtmf ) system may be used in cases where the customer with the disconnected number 14 has several locations . for example , a user may be prompted to enter one to forward to a first particular location , two to forward to another location , etc . alternatively , the call forwarding system may be limited to certain times of the day . for example , a business subscriber may elect to pay for call forwarding during normal business hours only . thus , at times other than normal business hours , the lion query could indicate that the service is calling party pays and the calling party will be prompted to see if the calling party would like to pay for the call forwarding .