Abstract:
A call control system for controlling testing in a mobile switching center (MSC) comprises an interface and a processing system. The interface is configured to receive a test call from a test device to a tone card internal to the MSC. The processing system is configured to determine a primary route for routing the test call to the tone card for a first duration, generate first routing instructions indicating the primary route, after the first duration determine a secondary route for routing the test call to the tone card during a second duration, and generate second routing instructions indicating the secondary route.

Description:
RELATED APPLICATIONS 
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     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
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     MICROFICHE APPENDIX 
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     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to wireless telecommunication technologies, and in particular, to wireless telecommunication service testing. 
     2. Description of the Prior Art 
     In wireless telecommunication networks, mobile switching centers (MSCs) provide call control and switching for calls placed by wireless customers using wireless handsets. The wireless handsets communicate wirelessly with base stations, which in turn are coupled to MSCs over hardwired connections, such as T-1 lines. MSCs are commonly capable of terminating calls to other wireless customers, as well as to destinations on the public switched telephone network (PSTN). 
     Often times, it is desirable to test the performance of MSCs. One prior art solution for testing MSC performance is to use a wireless test set to dial a local test number. In such a case, the MSC routes the test call to a switch in the local exchange carrier (LEC) network. The switch terminates the call to a specialized port that provides audio feedback to allow an test engineer to determine the quality of the connection to the MSC. One drawback to this solution is that the LECs frequently change local test numbers without providing updates to wireless operators. Another drawback is that the LECs charge local access fees to the wireless operators when test calls are terminated to their networks. 
     One prior art solution to the problems associated with terminating test calls to LEC switches involves installing specialized tone cards in MSCs.  FIG. 1  illustrates communication network  100  in an example of the prior art for performing wireless service testing. Communication network  100  includes test set  101 , base station  105 , MSC  110 , and public switched telephone network  120 . MSC  110  includes routing system  113 , call control system  115 , and tone card  114 .  FIG. 2  illustrates the operation of communication network  110  in a prior art example of service testing. 
     Referring to  FIG. 2 , a call is initiated by a test operator placing a call to a specialized telephone number. Call control system  113  processes the phone number using a group of database tables typically referred to as translation tables. The translation tables store routing information in association with phone numbers. Based on the routing information stored in association with the phone number for the tone card, call control system  113  directs routing system  112  to route the incoming call from test set  101  to tone card  114 . Call setup is performed between test set  101  and call control system  113  to establish a call connection between test set  101  and tone card  114 . 
     Once the test call is connected, tone card  114  provides tone to test set  101  to enable the test operator to check service quality. In this manner, wireless operators can maintain the test numbers themselves, rather than relying upon a LEC. This solution also eliminates the access charges incurred when terminating to a LEC. 
     In one problem, current tone cards only allow for testing for a limited amount of time, such as for 255 seconds. As a result, specialized processing elements of call control system  113  are typically programmed to monitor the duration of test calls to tone card  114  and end the calls at the expiration of a specific time period. Upon reaching the time limit, call control system  113  directs that a circuit busy signal be generated and provided to test set  101 . Call control system  113  also directs that the call connection to tone card  114  be torn down. The operator must then redial the phone number if it is desired to continue testing. 
     Unfortunately, prior art tone cards are designed and manufactured by third parties and affecting a change in the design to allow for extended testing would therefore be impractical. In many cases, this time limit significantly hinders the ability of wireless operators to test MSC performance. For example, in such a small amount of time it is not possible for a test operator to move across multiple cells to test how well an MSC handles handoffs between base stations. The specialized processing elements of call control system  114  could be modified to eliminate or bypass the time limits that are set at the beginning of a test call. However, such modifications must be implemented by the MSC manufacturer in response to a request for feature by the wireless operators and are typically prohibitively expensive. 
     SUMMARY OF THE INVENTION 
     An embodiment of the invention helps solve the above problems and other problems by providing systems, methods, and software that allows for sustaining a wireless test call to a tone card internal to an MSC for an unlimited period of time. In addition, an embodiment of the invention eliminates the need for an expensive request for feature and the need for a redesigned tone card. 
     In an embodiment of the invention, a call control system for controlling testing in a mobile switching center (MSC) comprises an interface and a processing system. The interface is configured to receive a test call from a test device to a tone card internal to the MSC. The processing system is configured to determine a primary route for routing the test call to the tone card for a first duration, generate first routing instructions indicating the primary route, after the first duration determine a secondary route for routing the test call to the tone card during a second duration, and generate second routing instructions indicating the secondary route. 
     In an embodiment of the invention, the interface is configured to transfer the first routing instructions and the second routing instructions to a routing system internal to the MSC. 
     In an embodiment of the invention, the interface is configured to receive the test call from a first base station in communication with the test device and wherein the processing system is configured to handoff the test call from the first base station to a second base station during the test call. 
     In an embodiment of the invention, the test call is connected to the interface over a first leg and wherein the test call remains connected to the interface over the first leg during the first duration and the second duration. 
     In an embodiment of the invention, the tone card is configured to provide tone to the test device during the test call. 
     In an embodiment of the invention, the processing system is configured to determine the secondary route in response to the end of the first duration. 
     In an embodiment of the invention, a method of operating a call control system for controlling testing in a mobile switching center (MSC) comprises receiving a test call from a test device to a tone card internal to the MSC, determining a primary route for routing the test call to the tone card during a first duration, generating first routing instructions indicating the primary route, after the first duration, determining a secondary route for routing the test call to the tone card during a second duration, and generating second routing instructions indicating the secondary route. 
     In an embodiment of the invention, a software product for operating a call control system to control testing in a mobile switching center (MSC) comprises software and a storage medium configured to store the software. The software is operational when executed by a computer system to direct the computer system to receive a test call from a test device to a tone card internal to the MSC, process the test call to determine a primary route for routing the test call to the tone card during a first duration, generate first routing instructions indicating the primary route, after the first duration determine a secondary route for routing the test call to the tone card during a second duration, and generate second routing instructions indicating the secondary route. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The same reference number represents the same element on all drawings. 
         FIG. 1  illustrates a communication network in an example of the prior art. 
         FIG. 2  illustrates the operation of a communication network in an example of the prior art. 
         FIG. 3  illustrates a communication network in an embodiment of the invention. 
         FIG. 4  illustrates a call control system in an embodiment of the invention. 
         FIG. 5  illustrates a call flow diagram in an embodiment of the invention. 
         FIG. 6A  illustrates a translation table in an embodiment of the invention. 
         FIG. 6B  illustrates a translation table in an embodiment of the invention. 
         FIG. 7  illustrates a process for the operation of a call control system in an embodiment of the invention. 
         FIG. 8  illustrates a communication network in an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIGS. 3-8  and the following description depict specific embodiments of the invention to teach those skilled in the art how to make and use the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these embodiments that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple embodiments of the invention. As a result, the invention is not limited to the specific embodiments described below, but only by the claims and their equivalents. 
     Configuration and Operation— FIGS. 3-8   
       FIG. 3  illustrates communication network  300  in an embodiment of the invention. Communication network  300  includes MSC  310 , test set  301 , base stations  305 ,  306 , and  307 , base station controller (BSC) and  311 . MSC  310  includes routing system  313 , call control system  315 , and tone card  314 . 
     Test set  301  operatively communicates wirelessly with base station  306  in accordance with wireless protocols well known in the art, such as general service mobile (GSM), code division multiple access (CDMA), and wireless fidelity (WiFi). Other wireless protocols are possible. Test set  301  could be, for example, a wireless phone, as well as other types of test sets. Base station  306  is coupled to BSC  311  by a well known backhaul link. BSC controls base station  306  and is further coupled to MSC  310  by a well known backhaul link. Routing system  313  could include interface systems that provide interface capabilities for MSC  310  for interfacing bearer traffic and signaling traffic. Similarly, routing system  313  could include interface systems to provide interface capabilities to control system  315  and tone card  314 . Routing system  313  is any routing system capable of routing communications between interface systems  312  and  311 . Routing system  313  is additionally any routing system capable of internally routing communications for call control system  315  and tone card  314 . 
     Call control system  315  could be any system capable of controlling calls incoming and outgoing to and from MSC  310 . For example, call control system  315  is capable of providing call control over calls placed by wireless customers to destinations on PSTN  320 . Call control is well understood in the art. Call control system  315  could be further capable of controlling test calls to tone card  314 . Tone card  314  could be any tone card capable of receiving a test call and providing tone in response to the call. 
       FIG. 4  illustrates call control system  315  in further detail. Call control system  315  includes processing system  317 , interface  316 , and database system  318 . Database system  318  could comprise translation tables and a database engine capable of processing the translation tables. Processing system  317  could be any processing system capable of interfacing with database system  318  to provide call control for MSC  310 . Processing system  317  could comprise hardware, software, firmware, or special purpose circuitry, or any combination thereof capable of providing call control. Processing systems and database systems are well known in the art. Interface  316  could be any interface capable of providing interface functions between call control system  315  and other elements of MSC  310 . 
     The following describes an example of a typical wireless phone call handled by MSC  310 . An end user using a wireless device places a phone call to a destination on PSTN  320 . The user dials a series of digits. The dialed digits are transmitted over the wireless backhaul to MSC  310 . Routing system  313  receives the dialed digits and passes the digits to call control system  315 . Call control system  315  applies well known call control processes, such as call validation, to the dialed digits. The dialed digits are eventually passed to database system  318  to determine a route for the call. The database engine of database system  318  access the translation tables of database system  318  to look-up the primary route for the call based on the dialed digits. Routing instructions are passed back to call control system  315 . 
     Call control system  315  provides the routing instructions to routing system  313 . The routing instructions could be provided in the form of control messages, signals, or the like. The call could be incoming to a particular port on routing system  313 . In accordance with the routing instruction, routing system  313  could route the incoming call to an appropriate outgoing port on interface system  311 . The outgoing port links the incoming leg of the call to an appropriate destination on PSTN  320 , such as a telecommunication switch. Call signaling for the call can also be passed by interface system  311 . External signaling channels are also possible. 
     In some cases, the primary route to a destination is unavailable. In such a case, control system  315  accesses the same translation tables to determine a secondary route to the destination. Assuming the secondary route is available, the call can be connected over the secondary route. 
       FIG. 5  illustrates a call flow diagram in an embodiment of the invention. In this embodiment, test set  301  and call control system  315  engage in call setup, including transmittal of dialed digits to call control system  315 . Call control system  315  determines routing instructions for the call and transfers the routing instructions to routing system  313 . Routing system  313  connects the test call to tone card  314 . Importantly, the incoming leg of the call from test set  301  traverses base station  306  and BSC  311 . Tone card  314  provides test tone to test set  301  during a first time period. 
     Internal to call control system  315 , a timer monitors the duration of the test call against a time limit. At the end of the time limit, call control system  315  releases tone card  314  from the call. Tone card  314  would otherwise cease providing tone at the expiration of a hard coded time limit, such as 255 seconds. Upon releasing tone card  314  from the call, call control system  315  proceeds to determine a secondary route for the call rather than tearing down the incoming call leg from test set  301 . Upon determining the secondary route, routing instructions are transferred to routing system  313 . Routing system  313  establishes a new connection internally to tone card  314 . Tone card  314  perceives that a new call has been established and responsively provides tone to test set  301 . 
       FIG. 6A  illustrates translation table  600 A in an embodiment of the invention. Translation table  600 A could be an example of a translation table stored in database system  318 . Translation table  600 A depicts two columns, although more columns are possible. From left to right, the first column stores phone numbers in the XXX-XXX-XXXX format. The second column holds keys associated with the phone numbers. 
       FIG. 6B  illustrates translation table  600 B in an embodiment of the invention. Translation table  600 B could be an example of a translation table stored in database system  318 . Translation table  600 B depicts three columns, although more columns are possible. From left to right, the first column stores keys. The keys are used as an index to routing commands. The second column stores a primary route. The third column stores a secondary route. As indicated in  FIG. 3 , key  1  has a primary route A and a secondary route X. Key  2  has a primary route B and a secondary route Y. 
     As further indicated in  FIG. 6B , key  800  indicates a primary route as tone card  314 . The secondary route for key  800  is a pointer to key  801 . The primary route associated with key  801  is again tone card  314 . The secondary route associated with key  801  is a pointer to key  800 . In this manner, a loop is created in translation table  600 B. 
       FIG. 7  illustrates process  700  for the operation of control system  315  in an embodiment of the invention. To begin, MSC  310  receives a test call from test set  301  (Step  710 ). The test call includes dialed digits. The dialed digits are passed to call control system  315 . Call control system  315  determines the primary route for the test call (Step  720 ). Internal to call control system  315 , processing system  317  queries database system  318  with the dialed digits. The database engine of database system  318  accesses translation table  600 A to determine the key associated with the dialed digits. In this case, the dialed digits are XXX-XXX-XXXC, and the key is  800 . 
     Next, the database engine accesses translation table  600 B to determine the primary route based on the key  800 . The primary route indicates that the call should be routed internally to tone card  314 . Database system  318  passes the primary route back to processing system  317 . Processing system  317  responsively generates routing instructions indicating the primary route and transfers the routing instructions to routing system  313  (Step  730 ). The call is then connected to tone card  314 . Tone card  314  responsively provides audible tone to test set  301  over the connection. 
     Upon connecting the call to tone card  314 , processing system  317  initiates a timer to limit the duration of the call. Upon expiration of the duration (Step  740 ), processing system  318  proceeds to determine the secondary route for the call (Step  750 ). Processing system queries database system  318  with the dialed digits and an indicator that the primary route is unavailable. The database engine of database system  318  accesses translation table  600 B using the key to determine the secondary route associated with the key. In this case, the secondary route associated with key  800  points to key  801 . The database engine jumps to key  801  and reads the primary route. In this case, the primary route for key  801  is tone card  314 . The database engine passes an identifier for tone card  314  back to processing system  317 . Processing system  317  responsively generates routing instructions for the call to be routed internally to tone card  314  (Step  760 ). The routing instructions are transferred to routing system  313 . The routing instructions direct routing system  313  to route the call to tone card  314 . 
     Processing system  317  can again initiate a timer to limit the duration of the call. Upon expiration of the duration (Step  770 ), processing system  317  transfers a query to database system  318  indicating the dialed digits and that the primary route is unavailable. In response, the database engine accesses translation table  600 B to determine the secondary route associated with key  801 . In this case, the secondary route associated with key  801  points to key  800 . The database engine responsively reads the primary route associated with key  800 , which in this case is tone card  314 . A response is transferred back to processing system  317  indicating that the call should be connected to tone card  314 . 
     Advantageously, process  700  could be repeated indefinitely to allow an operator using test set  101  to conduct test operations beyond the timed duration allowed for calls to tone card  314 . The loop created by translation table  600 B allows the incoming leg of the test call from test set  301  to remain up. In addition, the loop created in translation table  600 B allows the internal route to tone card  314  can be re-established at the end of each predetermined or preprogrammed duration. In this manner, the need for a request for feature is eliminated and the configuration of processing system  317  remains unchanged. In addition, the configuration of tone card  314  remains unchanged. 
       FIG. 8  illustrates a roaming example with respect to communication network  300 . In this example, an operator using test set  301  is able to roam between base stations  305 ,  306 , and  307  due to the ability of call control system  315  to continuously re-establish connections internally to test card  314 . In this manner, sustained wireless service testing is possible.