Abstract:
A system and method for providing simultaneous ringing service to a plurality of customer premises equipment. The method and system utilize a centralized database of subscriber information and a service node to make multiple outbound calls from the service node to multiple telephone lines assigned to a subscriber. The subscriber&#39;s telephone lines may include one or more wireless lines. Inbound calls to the subscriber&#39;s primary wireline are intercepted by the simultaneous ringing service and forwarded to the service node for processing.

Description:
BACKGROUND 
     1. Field of the Invention 
     The present invention relates generally to telecommunications systems and services provided in an advanced intelligent network (“AIN”) environment and more specifically to telecommunication systems for simultaneously ringing multiple subscriber lines when a single call is placed to a subscriber&#39;s primary line. 
     2. Background of the Invention 
     Multiple communications systems have become ubiquitous in today&#39;s society. It is not uncommon for individuals, referred to herein as “subscribers,” to have more than one telephone system including both wireline telephones and wireless telephones. Subscribers&#39; wireline telephones may or may not be co-located in the same building and the wireless telephones are, by design, highly mobile. This situation has resulted in a need for subscribers to maintain and distribute multiple telephone numbers which may be used to establish communication. 
     When a caller tries to reach a subscriber, the caller must dial the subscriber&#39;s first telephone number and wait to see if anyone answers the call. If the call goes unanswered, the caller must try the next number and again wait for an answer. This process must be repeated until one of the calls is answered or the caller has tried all of the subscriber&#39;s numbers without success. This situation can be frustrating for a caller because multiple telephone calls may have to be tried before successfully reaching the subscriber. Similarly, subscribers can be frustrated because the end result may be a missed call. Simultaneous ring services have been offered to solve this problem for subscribers having multiple telephone numbers. 
     In a simultaneous ring service, when a call is made to a subscriber&#39;s wireline (“primary line”) telephone number, the service provides a ringing tone on the primary line and on designated secondary lines. Such a service connects the caller to whichever telephone line is answered first. As known in the art, such simultaneous ring services may be extended to ring many different lines, wired or wireless, at the same time or to ring a series of lines in rapid succession. For simplicity, the description of conventional simultaneous ring services and the system and service of the present invention will be generally directed to simultaneous ringing of only two telephone lines. One of ordinary skill in the art will recognize how such services can be adapted to ring more than two lines simultaneously. 
     Although such simultaneous ring services have solved the subscribers&#39; problems, the implementation used in conventional services has resulted in further problems for the telephone service providers (“telcos”). Conventional simultaneous ring services are implemented using a service node (“SN”) comprising the telco&#39;s customer subscription data as described in more detail below. 
     Conventional Simultaneous Ring Service 
     Caller  110  in FIG. 1 is the person attempting to reach subscriber  112 , a customer of telco  128 . Caller  110  has telephone line  111 . As known in the art, caller  110  could also be a customer of telco  128 , or, caller  110  could be a foreign customer connecting through inter-exchange carrier (“IXC”)  114  as shown in FIG.  1 . In the schematic diagram shown in FIG. 1, when caller  110  places a call to subscriber  112 &#39;s primary line (i.e., wireline  113 ) the call hits a termination attempt trigger (“TAT”) on service switching point (“SSP” or “switch”)  115 . In response to this trigger, SSP  115  sends a query to service control point (“SCP”)  116  via signaling network  118 . As known in the art, signaling network  118  is a packet switched network consisting of various network components, including, e.g., signaling transfer points (“STPs”), SSPs, SCPs and the like. Common Channel Signaling System Number 7 (“SS7”) is a network protocol commonly used in signaling networks in North America, although other protocols may be implemented elsewhere or in the future. For the present invention, the specific signaling network protocol implemented is not important. 
     As known in the art, SCP  116  uses data stored in database  119  to formulate an appropriate answer to AIN queries it receives. Database  119  typically stores a plurality of records associated with each subscriber of the various services provided by the particular SCP. In the case of a conventional simultaneous ring service, database  119  includes the telephone numbers for the subscriber&#39;s primary line and designated secondary lines, including wireless line  122 . The database further includes information regarding the type of line used for each secondary line (i.e., whether the lines are wirelines or wireless lines). In response to the query from SSP  115 , SCP  116  first checks database  119  to see if the calling party number corresponds to one of the subscriber&#39;s designated secondary lines. If a match is made, SCP  116  instructs SSP  115  to continue with normal call processing, i.e., wireline  113  rings if it is available or caller  110  is provided a busy signal if wireline  113  is busy. If a match is not made, SCP  116  directs SSP  115  to forward the call to SN  124  for further call processing. As known in the art, SN  124  could be served by the same switch as the subscriber, or could be served by a different switch. In FIG. 1, SN  124  is served by a different switch, SSP  125 , via PRI trunk  126 . 
     As shown in FIG. 1, in conventional simultaneous ring services SN  124  uses database  127  to store a plurality of records associated with subscriber of the service. Just as with database  119  (on SCP  116 ) database  127  (on SN  124 ) stores telephone numbers for the subscriber&#39;s primary and secondary lines and type information for the secondary lines. As described above, SSP  115  forwards the call the SN  124  for further call processing. SN  124  uses the subscriber&#39;s primary line telephone number, contained in the redirecting party number field of the call setup message, to identify the subscriber being called. SN  124  looks up the subscriber&#39;s secondary numbers in database  127  and initiates calls to each secondary number as well as to the primary number. SN  124  prioritizes and spaces these calls as necessary if any of the secondary lines are wireless lines. As soon as one of these calls is answered, SN  124  connects caller  110  to the answered line and ends the unanswered calls. As discussed above, this conventional simultaneous ring service provides the functionality needed from the subscriber&#39;s and the caller&#39;s point of view. However, the conventional implementation described above is not efficient for the telco providing the service. 
     As known in the art service nodes as very expensive systems and are generally for specific applications. If the load on a particular service node is heavy, multiple service nodes may be required to accommodate an application. Because conventional implementation requires subscription data to be stored on a service node, telco  128  must maintain multiple databases on multiple network nodes. Moreover, the information in these databases is duplicative of the information already needed to be stored in the service control point as described above. A need therefore exists for a more efficient system and method for providing simultaneous ring services for subscribers. 
     SUMMARY OF THE INVENTION 
     The present invention provides a system and method for providing simultaneous ringing on multiple subscriber telephone lines using a centralized database for storing the information related to the subscriber&#39;s lines. The database is stored on a centralized AIN node, usually a service control point, and it includes the telephone numbers for a subscriber&#39;s primary line and one or more secondary lines. When a caller places a call to the subscriber&#39;s primary line, a trigger is encountered at the switch serving the subscriber&#39;s primary line. In response to the trigger, the subscriber&#39;s switch queries the service control point for call processing instructions. In response to this query, the service control point instructs the subscriber&#39;s switch to forward the call to a service node. In one embodiment, the service control inserts a code indicating the quantity of wireless lines and the total quantity of secondary lines designated by the subscriber. When the service node receives the forwarded call, it initiates a series of outbound calls to the subscriber&#39;s primary and secondary lines as described below. 
     Because the service node in the present invention does not have any local subscription data, it relies on the service control point to provide the information from its centralized database. To accomplish this, the service node places a call to the subscriber&#39;s primary line number, which it retrieves from the information provided within the original forwarded call. In placing this call, the service node inserts a special identification code into the redirecting party number field of the call setup message. This identification code is used to indicate which of the subscriber&#39;s designated telephone number is being requested, i.e., whether the first, second, third, etc. telephone number is needed. In one embodiment of the present invention, the switch serving the service node is provisioned with an appropriate trigger that temporarily suspends this call while the switch queries the service control point for call processing instructions. In a second embodiment of the present invention, the trigger on the subscriber&#39;s line is used to initiate the query. 
     The service control point uses the subscriber&#39;s primary telephone number (found in the called party number field) and the identification code (found in the redirecting party number field) to retrieve the corresponding secondary telephone number from its database. In one embodiment, the service control point provides telephone numbers corresponding to wireless secondary lines prior to providing wireline numbers. In this manner, the service node spaces the calls out to ensure proper timing for the calls as described in more detail below. 
     The service control point inserts the retrieved secondary telephone number into the called party number field and instructs the switch to continue call processing using the telephone number provided. The service node repeats these steps for each telephone number in the subscriber&#39;s designated list of lines to ring via this service. If one of the called lines is answered, the service node drops the other calls and stops initiating new calls. The caller is then connected to the answered call. If none of the called lines are answered, the service node drops all of the calls. In one embodiment of the present invention, the service node provides an appropriate announcement to the caller. 
     In one embodiment of the present invention, the simultaneous ringing service performs many additional functions such as checking the status of each line prior to placing the simultaneous calls, or checking to see if the calling party number is one of the subscriber&#39;s designated lines. Further, the service can provide an administration system that allows subscribers to change the status of their subscription and to add or delete lines from the database. Finally, in one embodiment of the present invention, a heartbeat call from the service node to the service control point is provided for tracking the availability of the service node for processing simultaneous ring services. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic diagram showing a prior art system for providing simultaneous ringing service. 
     FIG. 2 is a schematic diagram showing a general system architecture used in an embodiment of the present invention. 
     FIGS. 3 a  and  3   b  are flow charts showing the call flow for a first embodiment of the present invention. 
     FIGS. 4 a  and  4   b  are flow charts showing the call flow for a second embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is best described by providing a detailed description of the call flow in a first embodiment of the present invention. The following description also provides call flows and descriptions for alternative embodiments as noted. FIG. 2 shows the AIN architecture used in the first and alternative embodiments of the present invention and referenced in the call flow descriptions below. An administration system allowing the subscriber to manage his or her simultaneous ringing service is described. Finally, an embodiment for including status messages sent between the SN and the SCP is described. 
     Call Flow 
     The call flow used in the first embodiment of the present invention is detailed in FIGS. 3 a  and  3   b . Caller  210  initiates the simultaneous ring service by dialing the telephone number for subscriber  212 &#39;s primary line, wireline  213 . In step  300 , the call is received by SSP  215 . In step  302 , a TAT on wireline  213  at SSP  215  causes SSP  215  to send an AIN query message to SCP  216 . As described above, query and response messages are sent between AIN nodes via signaling network  218 . In response to the query, SCP  216  provides call processing instructions carrying out the simultaneous ring service as described below. 
     In step  303 , SCP  216  checks to see if the call originated at the service node. In one embodiment, SCP  216  accomplishes this step by checking the originating number field for the call. If the originating number corresponds to SN  224 , then SCP  216  recognizes that this call is already being handled by the simultaneous ring service. In another embodiment, SCP  216  checks the redirecting party number field to see if a service node has entered any special codes in the field. If SCP  216  determines that the call originated from a service node, the call flow continues at point A in FIG. 3 b , described in later sections, below. If the originating party number is not associated with SN  224  the call flow moves on to step  304 . In step  304 , SCP  216  checks the calling party number (“CgPN”) field in the query message to determine whether or not the caller is calling from one of the subscriber&#39;s designated numbers. SCP  216  looks up the called party number (“CdPN”), i.e., the subscriber&#39;s primary number in database  219  to see if the CgPN is associated with it. If the CgPN is found in database  219 , there is no need to ring the wireless number since the subscriber is using one of the secondary lines to call home and the call flow moves on to step  305  where SCP  216  provides an Authorize_Termination response to SSP  215 . In step  306 , SSP  215  completes normal call process, i.e., caller  210  receives a ringing tone, a busy tone, or other normal call termination messages. 
     If the CgPN was not found in database  219 , the call flow moves on to step  307  where SCP  216  checks the current status of the subscriber&#39;s simultaneous ring service. If the subscriber&#39;s service is turned off, the call flow moves on to step  305  and SCP  216  sends an Authorize_Termination response and normal call processing continues as described above. If the subscriber&#39;s simultaneous ring service is on, the call flow moves on to step  308  where SCP  216  checks to see if SN  224  is available. If SN  224  is not available, the simultaneous ring service will not be provided and the call flow moves on to step  305  as described above. 
     In step  310  SCP  216  queries the network to determine the status of subscriber  212 &#39;s telephone lines. If, in step  312 , the subscriber&#39;s primary line, i.e., wireline  213 , is busy, there is no need for simultaneous ringing because the subscriber is known to be at that location. In this case, the call flow moves on to step  305  for normal call processing as described above. Similarly, if, in step  314 , any of the subscriber&#39;s secondary lines are busy there is no need for simultaneous ringing so the call flow moves on to step  305  for normal call processing. Otherwise, if the subscribers primary line and all of the secondary lines are available the call flow moves on to step  316 . 
     In step  316  SCP  216  responds to the query with a Forward_Call message instructing SSP  215  to route the call to SN  224 . As known in the art, the redirecting party number field in the Forward_Call message is fifteen characters long and would contain the subscriber&#39;s primary number (i.e., the original CgPN) with leading zeros or blanks to fill the first five characters. In step  316 , SCP  216  modifies the redirecting party number by appending a code to indicate the quantity of wireless lines and total quantity of secondary lines (including the subscriber&#39;s primary line). In the first embodiment of the present invention, the code is appended to the beginning of redirecting party number field of the Forward_Call response message. For example, if the subscriber has designated two different wireless lines and two other wirelines to receive simultaneous ringing, SCP  216  appends a code such as “23” to the redirecting party number field. If, e.g., the subscriber&#39;s primary line number is “2122223333” the redirecting party number field would be “230002122223333.” In step  318 , SSP  215  follows SCP  216 &#39;s instructions and forwards the call to SN  224  with the redirecting party number field as modified by SCP  216 . 
     In step  320 , SN  224  receives the call and sets appropriate timers and a call counter. The timers include a Call_Timer and a Wireless_Timer. The Call_Timer is set to the maximum time (“MaxTime”) allowed for the simultaneous ring service to operate. If, as described below, the Call_Timer expires before any of the secondary lines are answered, caller  210 &#39;s call is connected to a call to the subscriber&#39;s primary line. In the preferred embodiment, MaxTime is 60 seconds. The Wireless_Timer is used to compensate for delays (“DelayTime”) inherent in establishing a call to a wireless line. SN  224  places calls to each of the wireless lines designated by the subscriber and waits for the Wireless_Timer to expire before placing calls to the wirelines. In the first embodiment, DelayTime is four seconds. The call counter (“Counter”) can be used to keep track of how many calls SN  224  has placed. Counter is initialized to “1” in step  318 . After step  320 , SN  224  initiates a series of telephone calls to the subscriber&#39;s primary and secondary lines as described below. 
     In step  322  SN  224  initiates a call to subscriber  212 &#39;s primary line (wireline  213 ) and writes the value of Counter in the redirecting party number field of the call setup message. For example, if Counter has a value of “1” SN  224  writes “1111111111” in the redirecting party number field. This code will be used by SCP  216  in later steps to retrieve the subscriber&#39;s first telephone number from database  219 . Similarly, if Counter has a value of “4” SN  224  writes “4444444444” in the redirecting party number field and SCP  216  will retrieve the fourth telephone number from the database. Because this call is place to the subscriber&#39;s primary line, the call flow branches back to step  300  as indicated in FIG. 3 a . The TAT on wireline  213  at SSP  215  is again encountered in step  300 , and SSP  215  sends another query to SCP  216  requesting call processing instructions in step  302 . This time, however, in step  303 , the originating party number is that of SN  224  so the call flow moves on to point A in FIG. 3 b . At the same time as this branch of the call flow is being executed, SN  224  continues on to step  324  where it increments Counter by one. 
     In step  326  SN  224  compares Counter with the quantity of wireless lines associated with subscriber  212 . Recall that SN  224  previously received this information from SCP  216  in step  316 . If Counter is not greater than the quantity wireless lines then SN  224  returns to step  322  and places another call to the subscriber&#39;s primary line (wireline  213 ) as described above. This time, the current (i.e., as incremented in step  324 ) value of Counter is written in the redirecting party number field so that the next telephone number will be retrieved by SCP  216  in later steps. If, in step  326 , Counter is greater than the quantity of wireless lines, the call flow moves on to step  328 . Step  328  represents a waiting state. That is, even if SN  224  has already placed calls to each wireless line, it waits until Wireless_Timer has expired (i.e., DelayTime has passed) before moving on to step  330 . 
     In step  330  SN  224  places another call to the subscriber&#39;s primary line (wireline  213 ) as described above. As described above, the current value of Counter is written in the redirecting party number field so that the next telephone number will be retrieved by SCP  216  in later steps. Again, call flow branches after SN  224  places the outbound call to the subscriber&#39;s primary line, and the process branches to step  300 . Meanwhile, in step  332  SN  224  increments Counter again then moves on to step  334 . In step  334 , if Counter is greater than the total quantity of lines designated by the subscriber for simultaneous ring service, no more calls need to be placed and the process moves on to point B in FIG. 3 b . If Counter is not greater than the total quantity of designated lines, SN  224  returns to step  330  to place another call to the subscriber&#39;s primary line as described above. 
     FIG. 3 b  picks up the call flow for calls placed from SN  224  to the subscriber&#39;s primary number. As described above in connection with steps  300 - 303 , all such calls encounter the TAT on the subscriber&#39;s line at SSP  215  and in response to the TAT, SCP  216  recognizes that the call originated from SN  224 . In step  336 , SCP  216  retrieves the value of Counter from the redirecting party number field of the query message from SSP  215 . In step  338 , SCP  216  retrieves the appropriate telephone number to be called by looking up the subscriber&#39;s primary line number (obtained from the CgPN field) and retrieving the Nth designated number, where N corresponds to Counter. 
     In step  340  SCP  216  writes the retrieved telephone number in the CdPN field and responds to the query by instructing SSP  215  to forward the call to the new CdPN in step  342 . In step  344 , SCP  215  forwards the call to the designated telephone according to SCP  216 &#39;s instructions. If the call is answered in step  346  SN  224  connects the caller in step  348 . In step  350  SN  224  drops any other calls that are in progress and drops out of call between caller  210  and the answered line. If in step  346  the call has not been answered, the call flow moves on to step  352 . In step  352 , Call_Timer is checked to see if MaxTime has passed. If MaxTime has passed, SN  224  moves on to step  354  and connects the caller to the subscriber&#39;s primary line. Then, in step  350 , SN  224  drops any other calls in progress and drops out of the connected call as described above. By connecting the caller to the primary line SN  224  ensures that caller  210  receives some form of call termination (i.e., a busy signal, ringing tone, etc.). In a second embodiment of the present invention, SN  224  could provide caller  210  with an announcement indicating that caller  212  is not available to take the call and forwards the call to a voice mail system. If, in step  352 , Call_Timer has not expired then the call flow returns to step  346  to see if the call has been answered yet as described above. 
     Steps  336  and beyond are performed each time SN  224  places another outbound call to the subscriber&#39;s primary line. That is, each time SCP  216  receives a query and the originating node was SN  224 , it looks up the next telephone number in subscriber  212 &#39;s designated list of simultaneous ringing lines. The calls are ongoing concurrently, that is, SN  224  places multiple calls at the same time or in very rapid succession so that the calls to each designated number being attempted at roughly the same time. If any one of the calls is answered (i.e., in step  346 ) the call flow moves on to steps  348  and  350  for final call processing as described above. Similarly, if none of the calls are answered before the maximum call timer expires, the call flow moves on to steps  354  and  350  for final call processing. 
     In an alternative embodiment of the present invention, in step  320 , SN  224  can provide an announcement to caller  210  such as “Please hold while your is being processed.” The announcement could also provide other informative messages, e.g., advertising, or could play music while the simultaneous ring services tries to locate the subscriber. In this embodiment, step  352  can be modified so that SN  224  plays a message to the caller explaining that the subscriber could not be reached. The caller could also be provided an option to connect to the subscriber&#39;s primary line in which case step  352  as previously described is performed. 
     FIGS. 4 a  and  4   b  show the call flow associated with a second embodiment of the present invention. This embodiment is also used to provide a more specific example of the messages that may be passed between the various AIN nodes when providing simultaneous ring services according to the present invention. In this example, the simultaneous ring service is configured to provide simultaneous ringing only to the subscriber&#39;s primary line and one secondary line. One of ordinary skill in the art can adapt the steps described above in connection with the first embodiment if more than two lines will receive simultaneous ringing. 
     In steps  400  and  402  caller  210 &#39;s call to wireline  213  encounters the TAT on the line and causes SSP  215  to send a Termination_Attempt query message to SCP  216 . In steps  403  through  408 , SCP  216  checks the CgPN, the subscriber&#39;s simultaneous ring subscription status, and the status of SN  224 , as described previously in corresponding steps  303  through  308 . Accordingly, if the call originated from SN  224  (i.e., for example “1111111111” is in the redirecting party number field in step  403 ) or the CgPN is in database  219  (step  404 ) or the subscription is turned off (step  407 ) or SN  224  is unavailable (step  408 ), SCP  216  responds to SSP  215  by sending an Authorize_Termination message (step  405 ) and normal call processing proceeds in step  406 . Otherwise, in step  410  SCP  216  sets Response_Timer to three seconds to insure call processing continues even if it fails to determine the status of the subscriber&#39;s wireline and wireless line in steps  411  and  412 . 
     In step  411 , SCP  216  checks the status of the subscriber&#39;s primary and secondary lines by sending queries to network nodes responsible for each line. That is, SCP  216  sends a LocationRequest query message to HLR  221  and a Monitor_For_Change instruction to SSP  215 . As known in the art, LocationRequest query message uses the IS- 41  protocol. In response to this query, HLR  221  should send SCP  216  a LocationRequest Return Result message indicating whether wireless line  222  is active, busy or inactive. Similarly, SSP  215  should return a Status_Reported message indicating whether wireline  213  is active or busy. In step  412 , SCP checks to see if the expected responses have been received before the Response_Timer expires. If so, call processing continues to step  413  where, if SSP  215  reports that wireline  213  is busy, SCP  216  determines that no simultaneous ringing is necessary. In this case, SCP  216  moves on to steps  405  and  406  and normal call processing is provided. Similarly, if wireless line  222  is either busy or inactive (as reported by HLR  221 ) SCP  216  determines that no simultaneous ringing is necessary and sends an Authorize_Termination message to SSP  215  (steps  405  and  406 ). Call processing continues after step  414  at point C in FIG. 4 b , as described below. 
     If, in step  412 , the Response_Timer has expired before receiving responses from either of HLR  221  or SSP  215 ,SCP  216  moves on to step  415 . In step  415 , SCP  216  assumes that both wireline  213  and wireless line  222  are available (i.e., active and not busy). Call processing continues after this step at point C in FIG. 4 b.    
     Continuing on in step  416 , SCP  216  responds to SSP  215  by sending a Forward_Call message to direct the call to SN  224 . In this embodiment, the redirecting party number field is simply the subscriber&#39;s primary line number, i.e., the number originally dialed by caller  210 . In step  418 , SSP  215  complies with the service control point&#39;s instructions and forwards the call to SN  224 . In step  420 , SN  224  answers the call an sets the Call_Timer to 60 seconds and Wireless_Timer to four seconds. Alternatively, when SN  224  answers the call, it may play an announcement to caller  210  informing the caller that the simultaneous ring service is attempting to reach the subscriber before setting the timers as described. In an another variation of this embodiment, the caller may be offered an opportunity to skip the simultaneous ring service and the service node acts accordingly. 
     Once the timers have been set in step  420 , SN  224  places an outbound call in step  422  to wireline  213  using the number retrieved from the redirecting party number field of the inbound call. Moreover, in step  422 , SN  224  inserts the code “1111111111” into the original called party number field of the outbound call to identify this call as a request for the subscriber&#39;s wireless line telephone. After the Wireless_Timer has expired (step  428 ) SN  224  places a second outbound call to wireline  213  in step  430 . This second call has the code “2222222222” in the original called party number field to identify it as a request to connect to the subscriber&#39;s wireline  213 . Both of these outbound calls encounter a trigger on SSP  225 , the switch service SN  224  as described below. 
     In this embodiment PRI trunk group  226  is provisioned with a Channel Setup PRI/Off-Hook Delayed (“OHD”) trigger on SSP  225 . Accordingly, when SN  224  originates any calls on the B channels of the PRI interface, the OHD trigger is encountered. In step  424 , in response to the OHD trigger SSP  225  sends an Info_Collected query to SCP  216  for call processing instructions. In response to this query, SCP  216  returns an Analyze_Route response in step  436 . Prior to sending this response, SCP  216  determines the appropriate calling parameters by examining the information provided by SN  224  in the call query message, as described below. 
     In this embodiment, the original called party number field indicates which call is being placed by SN  224 . In step  426 , SCP  216  retrieves the original called party number and determines which telephone number is required from database  219  in step  432 . In this example, when the first outbound call from SN  224  encountered the trigger, the original called party number field contains “1111111111” and SCP  216  moves on to step  434 . In step  434 , SCP  216  inserts the telephone number for subscriber  212 &#39;s wireless line  222  as indicated in database  219 . The second outbound call from SN  224  does not contain “1111111111” in the original called party field (in this example the field contains “2222222222”) so SCP  216  moves on to step  438 . In step  438  SCP  216  sets the redirecting party number field to a code, such as e.g., “1111111111” and leaves the wireline telephone number in the called party field. This code in the redirecting party number field is used in step  403  to determine the appropriate response to the TAT on wireline  213  as described above. 
     Using the parameters as set in either steps  434  or  436 , SCP  216  moves on the step  436  and sends the Analyze_Route response to SSP  225 . In step  440 , SSP  225  completes each call according to the instructions provided in SCP  216 &#39;s response message. In step  442 , SN  224  determines whether or not either telephone call has been answered. If so, SN  224  connects caller  210  to the answered call in step  446  and drops the unanswered in step  448 . If neither call has been answered (in step  442 ) SN  224  checks to see if Call_Timer has expired. If not, SN  224  returns to step  442  and checks to see if one of the calls has been answered. Otherwise, SN  224  plays a message to caller  210  in step  452 . The message could inform the caller that the subscriber could not be located or was not available to take the call. SN  224  then drops all of the calls is step  448  and the service is completed. 
     Using the Channel Setup PRI/OHD trigger in this embodiment allows SCP  216  to supply the wireless number to route the call and at the same time allows the caller&#39;s caller ID information to be displayed to the end-user. SN  224  provides the caller ID if it is “available” or marks the caller ID as “private/restricted” or “unavailable,” as appropriate. 
     Service Activation/Deactivation Menu 
     In one embodiment, the subscriber can turn the simultaneous ring service on and off by dialing an administration number on a central office switch (not shown in FIG.  2 ). A TAT trigger is assigned to the administration number on that switch. When the subscriber&#39;s call reaches the switch, the TAT is encountered causing the switch to launch a query to SCP  216 . SCP  216  looks up the calling party ID in database  219  to retrieve subscriber  212 &#39;s information. If the calling party ID information is not delivered (e.g., the line is marked private), SCP  216  issues a Send_to_Resource message to the switch directing the switch to play an announcement and collect the end-user subscriber ID and personal identification number (“PIN”). The subscriber ID is the number for wireline  213  or some other unique number associated with subscriber  212 . 
     An interactive menu is provided by the switch under SCP  216 &#39;s direction via Send_To_Resource and Resource_Clear messages. The end-user may hear an announcement stating the status of the service such as “Your Simultaneous Ring service is now on.” The menu allows the end-user to enable or disable the service as desired. In an alternate embodiment, a service node may be used to interact with the subscriber and the SCP instead of a switch. In this embodiment, the service node can be selected by the SCP in response to a TAT on the administration number at the switch. Thus, the programming logic for requesting information from the subscriber can be customized and placed on multiple service node to accommodate systems workloads. 
     Heart Beat Call 
     In one embodiment, SN  224  regularly communicates its status to SCP  216 . SN  224  periodically calls a telephone number set up for this purpose. The periodic call is known as a “heartbeat” call because as long as SCP  216  receives a status message, it assumes that SN  224  is “alive,” i.e., available to provide the simultaneous ring service. The interval between heart beat calls can be set as appropriate given the amount of congestion or other factors affecting performance of the SN. In one embodiment, the timer is set to 30 seconds. When the timer expires, SN  224  makes a PRI call by dialing the pre-defined heart beat number. SN  224  inserts various codes into the redirecting party number field to convey its status information to SCP  216 . The status information conveyed includes the time interval indicating when SCP  216  should receive the next heartbeat call. 
     Because SN  224  uses the PRI lines, the PRI Channel Setup/OHD trigger is encountered at SSP  225 . SSP  225  sends a query to SCP  216  which recognizes the call as a heartbeat call, based on the called party number field. SCP  216  retrieves the status information and updates SN  224 &#39;s status in database  219  and returns an appropriate response message to SSP  225 . In one embodiment, the response message is a Send_to_Resource message instructing SSP  225  to send a Release message to SN  224 . When SN  224  receives this message, it resets the timer for the next heartbeat call and ends the call. Moreover, SCP  216  coordinates with its mated SCP (not shown in FIG. 2) via an X.25 interface. In this manner, either SCP can serve the simultaneous ring service without interruption. 
     The foregoing disclosure of embodiments of the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many variations and modifications of the embodiments described herein will be obvious to one of ordinary skill in the art in light of the above disclosure. The scope of the invention is to be defined only by the claims appended hereto, and by their equivalents.