Patent Publication Number: US-8983046-B2

Title: Method and apparatus for providing end-to-end call completion status

Description:
This application is a continuation of U.S. patent application Ser. No. 13/595,725, filed Aug. 27, 2012, which is currently allowed and is a continuation of U.S. patent application Ser. No. 12/550,183, filed Aug. 28, 2009, now U.S. Pat. No. 8,254,540, which is a continuation of U.S. patent application Ser. No. 11/018,007, filed on Dec. 21, 2004, now U.S. Pat. No. 7,583,794, all of which are herein incorporated by reference in their entirety. 
    
    
     The present invention relates generally to communication networks and, more particularly, to a method and apparatus for providing end-to-end call completion status in packet-switched networks, e.g., Voice over Internet Protocol (VoIP) networks. 
     BACKGROUND OF THE INVENTION 
     Network providers often measure defects in their network to evaluate service quality and availability. Conventional counters of defects sometimes produce data that suggest many more defects than what have actually occurred. For example, when VoIP gateways, such as Border Elements, attempt to use a congested PRI, a defect code is generated even though the call is successfully routed to another PRI for final call completion. Calls being placed over least cost routing mechanisms also can generate false defect codes since a non-least-cost route may have been used instead of the least-cost route to complete the call setup. 
     Therefore, a need exists for a method and apparatus for enabling end-to-end call completion status in packet-switched networks, e.g., Voice over Internet Protocol (VoIP) networks. 
     SUMMARY OF THE INVENTION 
     In one embodiment, the present invention enables a method for following the state of a call and generating defects as function of call completion success as opposed to discrete events that happen at individual network elements during the call. The invention uses Call Detail Records (CDR) to analyze the end-to-end completion status to measure per call basis defects instead of using defect codes generated by network elements on a per equipment basis. CDR is data associated with a telephone call, including the calling and the called numbers, the date and timestamp, the duration, the call setup delay, and the final handling code of the telephone call. The final handling code is the code that indicates whether a call has been completed successfully, blocked or cut off. Defect codes generated during the call setup that are not reflecting the true end-to-end call completion status of a call will be ignored and the final handling code will be used instead. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The teaching of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which: 
         FIG. 1  illustrates an exemplary Voice over Internet Protocol (VoIP) network related to the present invention; 
         FIG. 2  illustrates an example of collecting CDR data to enable end-to-end call completion status in a VoIP network of the present invention; 
         FIG. 3  illustrates a flowchart of a method for collecting end-to-end call completion status in a VoIP network of the present invention; 
         FIG. 4  illustrates a flowchart of a method for consolidating end-to-end call completion status in a VoIP network of the present invention; and 
         FIG. 5  illustrates a high level block diagram of a general purpose computer suitable for use in performing the functions described herein. 
     
    
    
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. 
     DETAILED DESCRIPTION 
     To better understand the present invention,  FIG. 1  illustrates an example network, e.g., a packet-switched network such as a VoIP network related to the present invention. The VoIP network may comprise various types of customer endpoint devices connected via various types of access networks to a carrier (a service provider) VoIP core infrastructure over an Internet Protocol/Multi-Protocol Label Switching (IP/MPLS) based core backbone network. Broadly defined, a VoIP network is a network that is capable of carrying voice signals as packetized data over an IP network. An IP network is broadly defined as a network that uses Internet Protocol to exchange data packets. 
     The customer endpoint devices can be either Time Division Multiplexing (TDM) based or IP based. TDM based customer endpoint devices  122 ,  123 ,  134 , and  135  typically comprise of TDM phones or Private Branch Exchange (PBX). IP based customer endpoint devices  144  and  145  typically comprise IP phones or PBX. The Terminal Adaptors (TA)  132  and  133  are used to provide necessary interworking functions between TDM customer endpoint devices, such as analog phones, and packet based access network technologies, such as Digital Subscriber Loop (DSL) or Cable broadband access networks. TDM based customer endpoint devices access VoIP services by using either a Public Switched Telephone Network (PSTN)  120 ,  121  or a broadband access network via a TA  132  or  133 . IP based customer endpoint devices access VoIP services by using a Local Area Network (LAN)  140  and  141  with a VoIP gateway or router  142  and  143 , respectively. 
     The access networks can be either TDM or packet based. A TDM PSTN  120  or  121  is used to support TDM customer endpoint devices connected via traditional phone lines. A packet based access network, such as Frame Relay, ATM, Ethernet or IP, is used to support IP based customer endpoint devices via a customer LAN, e.g.,  140  with a VoIP gateway and router  142 . A packet based access network  130  or  131 , such as DSL or Cable, when used together with a TA  132  or  133 , is used to support TDM based customer endpoint devices. 
     The core VoIP infrastructure comprises of several key VoIP components, such the Border Element (BE)  112  and  113 , the Call Control Element (CCE)  111 , and VoIP related servers  114 . The BE resides at the edge of the VoIP core infrastructure and interfaces with customers endpoints over various types of access networks. A BE is typically implemented as a Media Gateway and performs signaling, media control, security, and call admission control and related functions. The CCE resides within the VoIP infrastructure and is connected to the BEs using the Session Initiation Protocol (SIP) over the underlying IP/MPLS based core backbone network  110 . The CCE is typically implemented as a Media Gateway Controller and performs network wide call control related functions as well as interacts with the appropriate VoIP service related servers when necessary. The CCE functions as a SIP back-to-back user agent and is a signaling endpoint for all call legs between all BEs and the CCE. The CCE may need to interact with various VoIP related servers in order to complete a call that require certain service specific features, e.g. translation of an E.164 voice network address into an IP address. 
     For calls that originate or terminate in a different carrier, they can be handled through the PSTN  120  and  121  or the Partner IP Carrier  160  interconnections. For originating or terminating TDM calls, they can be handled via existing PSTN interconnections to the other carrier. For originating or terminating VoIP calls, they can be handled via the Partner IP carrier interface  160  to the other carrier. 
     In order to illustrate how the different components operate to support a VoIP call, the following call scenario is used to illustrate how a VoIP call is setup between two customer endpoints. A customer using IP device  144  at location A places a call to another customer at location Z using TDM device  135 . During the call setup, a setup signaling message is sent from IP device  144 , through the LAN  140 , the VoIP Gateway/Router  142 , and the associated packet based access network, to BE  112 . BE  112  will then send a setup signaling message, such as a SIP-INVITE message if SIP is used, to CCE  111 . CCE  111  looks at the called party information and queries the necessary VoIP service related server  114  to obtain the information to complete this call. If BE  113  needs to be involved in completing the call; CCE  111  sends another call setup message, such as a SIP-INVITE message if SIP is used, to BE  113 . Upon receiving the call setup message, BE  113  forwards the call setup message, via broadband network  131 , to TA  133 . TA  133  then identifies the appropriate TDM device  135  and rings that device. Once the call is accepted at location Z by the called party, a call acknowledgement signaling message, such as a SIP-ACK message if SIP is used, is sent in the reverse direction back to the CCE  111 . After the CCE  111  receives the call acknowledgement message, it will then send a call acknowledgement signaling message, such as a SIP-ACK message if SIP is used, toward the calling party. In addition, the CCE  111  also provides the necessary information of the call to both BE  112  and BE  113  so that the call data exchange can proceed directly between BE  112  and BE  113 . The call signaling path  150  and the call data path  151  are illustratively shown in  FIG. 1 . Note that the call signaling path and the call data path are different because once a call has been setup up between two endpoints, the CCE  111  does not need to be in the data path for actual direct data exchange. 
     Note that a customer in location A using any endpoint device type with its associated access network type can communicate with another customer in location Z using any endpoint device type with its associated network type as well. For instance, a customer at location A using IP customer endpoint device  144  with packet based access network  140  can call another customer at location Z using TDM endpoint device  123  with PSTN access network  121 . The BEs  112  and  113  are responsible for the necessary signaling protocol translation, e.g., SS7 to and from SIP, and media format conversion, such as TDM voice format to and from IP based packet voice format. 
     Network providers often measure defects in their network to evaluate service quality and availability. Conventional counters of defects sometimes produce data that suggest many more defects than what have actually occurred. For example, when VoIP gateways, such as Border Elements, attempt to use a congested PRI, a defect code is generated even though the call is successfully routed to another PRI for final call completion. Calls being placed over least cost routing mechanisms also can generate false defect codes since a non-least-cost route may have been used instead of the least-cost route to complete the call setup. 
     To address this criticality, the present invention enables a method for following the state of a call and generating defects as function of call completion success as opposed to discrete events that happen at individual network elements during the call. The invention uses Call Detail Records (CDR) to analyze the end-to-end completion status to measure per call basis defects instead of using defect codes generated by network elements on a per equipment basis. CDR is data associated with a telephone call, including the calling and the called numbers, the date and timestamp, the duration, the call setup delay, and the final handling code of the telephone call. The final handling code is the code that indicates whether a call has been completed successfully, blocked or cut off. Defect codes generated during the call setup that are not reflecting the true end-to-end call completion status of a call will be ignored and the final handling code will be used instead. 
       FIG. 2  illustrates an example of collecting CDR data to enable end-to-end call completion status in a VoIP network. Various network elements or components in a VoIP network continuously collect per call CDR data for every call processed within the network. These network elements include CCE, BE, and AS. CDR is data associated with a telephone call, including the calling and the called numbers, the date and timestamp, the duration, the call setup delay, and the final handling code of the telephone call. The final handling code is the code that indicates whether a call has been completed successfully, blocked or cut off. Every call made using the VoIP network creates one CDR at each network element involved in the call. A CDR created at BEs  212  and  213  for a particular telephone call contain signaling and media information more related to the edge of the network for the call, while a CDR created at CCE  211  for the same telephone call contains signaling information more related to the core of the network for the call. CDR is created on a per call basis. In other words, there is only one CDR created for a telephone call for each network element involved in the call. 
     In order to monitor end-to-end call completion status of a call, all network elements within network  200  forward completed CDR data of each call to the Performance Server  214  for further analysis and processing. Flow  220  shows the collected CDR flow from BE  212 , BE  213 , CCE  211  and AS  215  to PS  214 . PS  214  processes and analyzes all collected CDR data from all network elements to provide an end-to-end view of call completion status of each call on a per call basis within the network. Particularly, PS  214  will consolidate all CDR data associated with a particular call to construct the end-to-end completion view of the call. PS  214  will put together CDR data with views from different network elements within the network to construct an end-to-end call completion view of the call. With the end-to-end completion view in place, the call completion data can be presented showing detailed call completion performance reflecting a much more accurate picture of the overall call completion performance. Defect codes generated during the call setup that are not reflecting the true end-to-end call completion status of a call will be ignored and the final handling code will be used instead. In other words, the present invention instead uses the final handling code as an indication or measure of a defect in the communication network, thereby reducing the number of falsely reported defects. 
       FIG. 3  illustrates a flowchart of a method for collecting end-to-end call completion status in a VoIP network. The method is executed by all CCEs, BEs, and ASs within the network. Method  300  starts in step  305  and proceeds to step  310 . 
     In step  310 , the method collects CDR data associated with a call. Namely CDR data from each and every network components involved in the call will be collected. 
     In step  320 , the method forwards the collected completed CDR data of the call to the PS. Method  300  ends in step  330 . 
       FIG. 4  illustrates a flowchart of a method for consolidating CDRs to construct end-to-end call completion status in a VoIP network. The method is performed by the Performance Server. Method  400  starts in step  405  and proceeds to step  410 . 
     In step  410 , the method receives CDRs collected by all VoIP network elements within the network. In step  420 , the method consolidates related CDRs based on a per call basis. Namely, the method identifies all CDRs associated with a particular call and uses the data with these related CDRs to construct the end-to-end call status view from the beginning of the call to the end of the call. 
     In step  430 , the method uses the end-to-end call status view to decide if the call is completed successfully or provides a reason for the failure of the call if the call has failed. Method  400  ends in step  440 . 
       FIG. 5  depicts a high level block diagram of a general purpose computer suitable for use in performing the functions described herein. As depicted in  FIG. 5 , the system  500  comprises a processor element  502  (e.g., a CPU), a memory  504 , e.g., random access memory (RAM) and/or read only memory (ROM), an end-to-end call completion status module  505 , and various input/output devices  506  (e.g., storage devices, including but not limited to, a tape drive, a floppy drive, a hard disk drive or a compact disk drive, a receiver, a transmitter, a speaker, a display, a speech synthesizer, an output port, and a user input device (such as a keyboard, a keypad, a mouse, and the like)). 
     It should be noted that the present invention can be implemented in software and/or in a combination of software and hardware, e.g., using application specific integrated circuits (ASIC), a general purpose computer or any other hardware equivalents. In one embodiment, the present end-to-end call completion status module or process  505  can be loaded into memory  504  and executed by processor  502  to implement the functions as discussed above. As such, the present end-to-end call completion status process  505  (including associated data structures) of the present invention can be stored on a computer readable medium or carrier, e.g., RAM memory, magnetic or optical drive or diskette and the like. 
     While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of a preferred embodiment should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.