Abstract:
A method and system enables distributed transaction oriented telephony functionality for telephony services in a broadband packet network. Exemplary distributed transaction oriented telephony functionality includes Intelligent Network (IN) and Advanced Intelligent Network (AIN) functionality accessed through the legacy Common Channel Signaling (CCS) network using transaction-based messaging protocols, such as Intelligent Network Application Part (INAP) and/or Transaction Capability Application Part (TCAP) protocols. A functional content of a transaction message, such as a TCAP message, is encapsulated in a Protocol Data Unit (PDU) of the broadband packet network. The PDU is forwarded through the broadband packet network to a second network element. The functionality is then invoked using the encapsulated transaction message functional content. In preferred embodiments the PDU is a Session Initiation Protocol (SIP) envelope, into which TCAP message functional content can be mapped.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is the first application filed for the present invention. 
     MICROFICHE APPENDIX 
     Not Applicable. 
     TECHNICAL FIELD 
     The present invention relates to intelligent network/advanced intelligent network (IN/AIN) services, and, in particular, to a method of enabling IN/AIN functionality for telephony services deployed in a broadband packet network. 
     BACKGROUND OF THE INVENTION 
     Modern telephony services deployed in the Public Switched Telephone Network (PSTN) commonly rely on distributed transaction oriented telephony functionality, such as, for example Intelligent Network and/or Advanced Intelligent Network (IN/AIN) functionality in order to deliver sophisticated call control services to subscribers. Typically, this distributed functionality involves various network elements (e.g. Service Control Points (SCP&#39;s), Intelligent Peripherals (IPe&#39;s) and Interactive Voice Response (IVR) servers) and transaction-based protocols (such as Intelligent Network Application Part (INAP), and Transaction Capability-Application Part (TCAP)) deployed in the Common Channel Signaling (CCS) network. INAP and TCAP operate over conventional Signaling System 7 (SS7) infrastructure, and supplements legacy Integrated Services Digital Network-User Part (ISUP) signaling by providing a query/response protocol for accessing routing information and telephony services provided by IN/AIN capable network elements within the CCS network. 
     A deficiency of the current PSTN/CCS network is that its monolithic architecture and slow (64 kbs) signaling speed reduces network scalability. As the amount of telephony traffic increases, network service providers have increasing difficulty provisioning sufficient CCS network resources to handle the associated ISUP and INAP/TCAP signaling. In this respect, one particular difficulty is the need to provide each network element (e.g. an SCP) with sufficient SS7 signaling ports. Typically, the number of SS7 signaling ports is limited by both the hardware and software of the network element implementation. In the case of legacy CCS network elements, the monolithic design of both the hardware and software tends to make the addition of new SS7 signaling ports difficult, and therefore expensive. However, failure to provision sufficient SS7 signaling ports can lead to port exhaustion, and consequent reduction in services as the affected network element is unable to accept any new ISUP or TCAP messages until a port becomes available. 
     Another limitation of the legacy CCS network is that its monolithic design, and the high cost of CCS network elements, create significant barriers to the entry of network service providers who lack CCS network infrastructure. 
     In order to address issues of scalability within the PSTN, various efforts have been made to deploy telephony services in a broadband packet network such as an internet protocol (IP) network. Various protocols have been proposed to enable this functionality, including various Voice over IP (VoIP) protocols for carrying bearer traffic, as well as session set-up and routing protocols (such as Multi-protocol Label Switched Path (MPLS) and Session Initiation Protocol (SIP)) for establishing communications sessions and for routing the bearer traffic through the network. In general, it is also possible to deploy resources in a broadband packet network that enable services similar to those provided by the legacy CCS network. However, in order to establish telephone connections between points in the PSTN and a packet network, interaction between resources of the broadband packet and CCS networks is essential. One method of accomplishing this has been proposed by V. Gurbani in an Internet Engineering Task Force (IETF) draft entitled “Accessing IN services from SIP networks”.  FIG. 1  is a block diagram illustrating the system of Gurbani for enabling IN/AIN functionality for telephony services deployed in a SIP network  2 . As shown in  FIG. 1 , Gurbani teaches an IN state machine  4  overplayed on the conventional SIP state machine  6  within a SIP server  8  of the SIP network  2 . The IN state machine  4  operates to generate conventional TCAP messages reflecting the state of the SIP state machine  6 , and forwards these messages though the legacy CCS network  10  to an IN/AIN capable device  12  (e.g. an SCP and/or an IPe). TCAP messages (e.g. response messages) are received over the CCS network  10  by the IN state machine  4  and passed to the SIP state machine  6  to control call setup through the SIP network  2 . 
     Thus, in the system of Gurbani, the IN state machine  4  operates as an interface between the SIP network  2  and the conventional CCS network  10 , which enables a SIP server  8  to emulate a Service Switch Point (SSP) of the PSTN for the purposes of accessing IN/AIN functionality. However, this system suffers from the limitation that it increases the amount of TCAP traffic in the CCS network  10 , and thus increases the risk of signaling port exhaustion in the CCS network element  12 . This risk increases as the amount of telephony traffic in the SIP network  2  increases. 
     Accordingly, a method and apparatus that enables access to distributed transaction oriented telephony functionality for telephony services deployed in a broadband packet network while mitigating the risk of signaling port exhaustion in CCS network elements, remains highly desirable. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a method and apparatus that enables access to distributed transaction oriented telephony functionality for telephony services deployed in a broadband packet network while avoiding signaling port exhaustion in CCS network elements. 
     Accordingly, an aspect of the present invention provides a method of enabling distributed transaction oriented telephony functionality for telephony services in a broadband packet network. A functional content of a transaction message is encapsulated in a Protocol Data Unit (PDU) of the broadband packet network. The PDU is forwarded through the broadband packet network to a second network element. The functionality is then invoked using the encapsulated transaction functional content. 
     Another aspect of the present invention provides a system adapted for enabling distributed transaction oriented telephony functionality for telephony services in a broadband packet network. The system comprises: a first network element adapted to encapsulate at least a functional content of a transaction message in a Protocol Data Unit (PDU) of the broadband packet network; and a second network element adapted to invoke the functionality using the enncapsulated transaction functional content. 
     Another aspect of the present invention provides a network node adapted to enable distributed transaction oriented telephony functionality for telephony services in a broadband packet network. The node comprises: means for encapsulating at least a functional content of a transaction message in a Protocol Data Unit (PDU) of the broadband packet network; and means for forwarding the PDU through the broadband packet network to a network element adapted to provide the functionality. 
     The broadband packet network comprises any one or more of: an Asynchronous Transfer Mode (ATM) network; an internet Protocol (IP) network; a Frame Relay (FR) network; and an Integrated Services Digital Network (ISDN). In preferred embodiments of the invention, the broadband packet network comprises an IP Network, and the PDU comprises a Session Initiation Protocol (SIP) message envelope. In such cases, the functional content of an IN/AIN message may be inserted into a Multipurpose Internet Mail Extension (MIME) part of the SIP envelope. 
     Each network element may comprise a media gateway controller adapted to enable telephony signal traffic through the broadband packet network, or an application server adapted to invoke IN/AIN functionality using IN/AIN functional content. An application server may be either: a CCS network element adapted to send and receive PDU&#39;s of the broadband packet network; or a network element of the broadband packet network. 
     Encapsulation of the functional content of the transaction message may comprise the steps of: formulating a conventional transaction message; and inserting the formulated transaction message into a payload portion of the PDU. 
     Alternatively, encapsulation of the functional content of the transaction message may comprise mapping a transaction message onto the PDU. In some embodiments, the transaction message is a Transaction Capability-Application part (TCAP) message. In such cases, a TCAP message type is mapped onto a respective message type of the PDU. The TCAP message type may comprise any of: query; response; conversation; unidirectional and abort. In other embodiments, the transaction message is an Intelligent Network-Application part (INAP) message. In such cases, an INAP message type is mapped onto a respective message type of the PDU. The INAP message type may comprise any of: begin; end; continue; unidirectional and abort. 
     A transaction message parameter may also be mapped onto a respective PDU message parameter. The message parameter may comprise any one or more of: an origination address and a destination address, and may be mapped to a respective overhead field of the PDU. Finally, an encoded transaction message payload may be mapped into a payload of the PDU. The encoded message payload may be mapped into a payload portion of a MIME part of the PDU. 
     In embodiments of the invention, the transaction message comprises two or more encoded payload portions. Each encoded payload portion may be mapped to a respective individual MIME payload. Alternatively, the encoded payload portions may be mapped to a common MIME payload. 
     An advantage of the present invention is that conventional TCAP message functional content can be transported across the broadband packet network to an Application Server to invoke IN/AIN functionality, without utilizing legacy CCS network infrastructure. Consequently, IN/AIN functionality can be invoked in respect of telephony services deployed in the broadband packet network, without contributing to signaling port exhaustion in the CCS network. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and advantages of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which: 
         FIG. 1  is a block diagram schematically illustrating operations of a prior art system for accessing IN/AIN functionality for telephony services in a broadband packet network; 
         FIG. 2  is a block diagram schematically illustrating operations of a system for accessing IN/AIN functionality for telephony services in a broadband packet network, in accordance with an embodiment of the present invention; 
         FIG. 3   a  is a message flow diagram showing principle messages exchanged in a TCAP query/response transaction in accordance with the prior art; 
         FIG. 3   b  is a message flow diagram showing principle messages exchanged in the query/response transaction of  FIG. 3   a  utilizing TCAP encapsulated within SIP in accordance with an embodiment of the present invention; 
         FIG. 4   a  is a message flow diagram showing principle messages exchanged in an AIN send-to-resource transaction in accordance with the prior art; 
         FIG. 4   b  is a message flow diagram showing principle messages exchanged in the AIN send-to-resource transaction of  FIG. 4   a  utilizing TCAP encapsulated within SIP in accordance with an embodiment of the present invention; 
         FIG. 5   a  is a message flow diagram showing principle messages exchanged in a TCAP Ring Again (RAG) transaction in accordance with the prior art; 
         FIG. 5   b  is a message flow diagram showing principle messages exchanged in the RAG transaction of  FIG. 5   a  utilizing TCAP encapsulated within SIP in accordance with an embodiment of the present invention; and 
         FIG. 6  is a block diagram schematically illustrating an exemplary model for a SIP envelope encapsulating TCAP functional content in accordance with an embodiment of the present invention. 
     
    
    
     It will be noted that throughout the appended drawings, like features are identified by like reference numerals. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention provides a method and apparatus for enabling Intelligent Network/Advanced Intelligent Network (IN/AIN) functionality for telephony services deployed in a broadband packet network.  FIG. 2  is a block diagram illustrating exemplary elements of a network  14  in which the present invention may be deployed. 
     As shown in  FIG. 2 , telephony services can be deployed within a broadband packet network  14  in a generally conventional manner. The broadband packet network  14  can be formed of one or more federated packet networks (e.g. Internet Protocol (IP), asynchronous transfer mode (ATM), frame relay (FR) and Integrated Services Digital network (ISDN)) with appropriate format adaptation at network boundaries. Communications sessions can be set up across the broadband packet network  14 , e.g. between media gateway controllers (MGCs)  16   a,   16   b  using any known session control protocol, such as, for example, Session Initiation Protocol (SIP), which may encapsulate legacy Integrated Services Digital Network-User Part (ISUP) messages to enable connections to be set up across the Public Switched Telephone Network (PSTN) (not shown). IN/AIN functionality is provided by an application server (AS)  18 , which may be provided as one or more legacy elements of the CCS network, such as, for example, Service Control Points (SCP&#39;s), Intelligent Peripherals (IPe&#39;s), and Interactive Voice Response (IVR) servers suitably adapted to enable signaling through the broadband packet network. Alternatively, the AS  18  may be provided as a server deployed in the broadband packet network  14 . In the embodiment illustrated in  FIG. 2 , a single AS  18  is provided for invoking IN/AIN functionality. It will be understood that IN/AIN functionality will normally be provided by two or more devices, working alone or in combination. For ease of description of the present invention, a simplified network topology is presented, in which the IN/AIN functionality is enabled by interaction between a single MGC  16   a  of the broadband packet network and a single AS  18 . It will be recognized, however, that the present invention is not limited to this simplified embodiment. 
     The present invention operates to enable Intelligent Network Application Part (INAP) and/or Transaction Capability-Application Part (TCAP) query/response transactions between MGCs  16  and application servers  18 , bypassing the CCS network infrastructure for message transport. This operation enables IN/AIN functionality for telephony services deployed in the broadband packet network  14 , without increasing the risk of port exhaustion in CCS network elements Thus in accordance with the present invention, at least the functional content of each INAP and/or TCAP message is encapsulated within a PDU of the broadband packet network, which is then used for message transport. In embodiments in which the AS  18  is provided by legacy CCS network elements (e.g. SCP&#39;s and IPe&#39;s), a logical connection between the broadband packet network  14  and the AS  18 , in order to facilitate transport of TCAP-encapsulating PDU&#39;s, can be established using existing IP, FR or ISDN ports of the AS  18 , which are commonly used for network management traffic. Alternatively, the AS  18  can be provisioned with new IP ports, in addition to and/or in place of existing SS7 ports. By virtue of the flexibility and scalability afforded by IP, it is typically easier and less expensive to add IP ports to an existing SCP, IVR, or IPe than it is to add equivalent SS7 ports. 
     The encapsulation of INAP and/or TCAP functional content within PDU&#39;s of the broadband packet network  14  will now be described in detail by way of an exemplary embodiment in which the broadband packet network  14  is an IP network (such as the public internet), and TCAP functional content is encapsulated within a SIP envelope. It will be appreciated that a closely similar method of encapsulation can be employed to encapsulate the functional content of INAP messages within PDU&#39;s of the broadband packet network  14 . Accordingly, the following description will focus on the encapsulation of TACP functional content, with the understanding that the present invention is not intended to be limited to TCAP, but rather also includes encapsulation of INAP functional content. 
     Encapsulation of TCAP functional content within a SIP envelope can be accomplished by either inserting a conventional TCAP message into a payload portion of the SIP envelope, or by mapping TCAP messages to corresponding SIP messages. An exemplary mapping between TCAP and SIP messages is described below. 
     In general, mapping between TCAP and SIP messages involves three mappings, namely: mapping TCAP message types to SIP message types; mapping TCAP parameters to SIP parameters; and mapping TCAP message content to SIP envelope payload. Each of these mappings will be treated, in turn, in the following description. 
     Mapping TCAP Message Types To SIP Message Types 
     The first aspect of mapping TCAP to SIP involves mapping TCAP message types to SIP message types and status codes. As is known in the art, SIP messages are either requests or responses. Tables 1 and 2 below show exemplary mappings between TCAP message types (for both ANSI and ITU-T versions of TCAP) and SIP request and response message types, respectively. 
     
       
         
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 SIP Request 
                 Description 
                 TCAP message type 
               
               
                   
                   
               
             
             
               
                   
                 INVITE 
                 Used to initiate a 
                 (ANSI) QUERY 
               
               
                   
                   
                 transaction 
                 (ITU-T) BEGIN 
               
               
                   
                   
                   
                 (ANSI and ITU-T) 
               
               
                   
                   
                   
                 UNIDIRECTIONAL 
               
               
                   
                 BYE 
                 Used to release a 
                 (ANSI and ITU-T) 
               
               
                   
                   
                 call that is 
                 ABORT 
               
               
                   
                   
                 currently 
               
               
                   
                   
                 connected 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 SIP Response/ 
                   
                   
               
               
                 Status Codes 
                 Description 
                 TCAP message type 
               
               
                   
               
             
             
               
                 1xx Informational 
                 Continuing to 
                 TCAP Message types 
               
               
                 100 Trying 
                 process the 
                 other than 
               
               
                 180/ 
                 request 
                 begin/end messages 
               
               
                 183 Ringing 
                 Phrases 
                 (ANSI) CONVERSATION 
               
               
                 182 Queued 
                 corresponding to 
                 (ITU-T) CONTINUE 
               
               
                 187 Processing 
                 the numeric 
               
               
                   
                 response codes may 
               
               
                   
                 be replaced with 
               
               
                   
                 local equivalents 
               
               
                   
                 without affecting 
               
               
                   
                 the protocol. 
               
               
                   
                 Additional codes 
               
               
                   
                 may be added as 
               
               
                   
                 desired. 
               
               
                 2xx Success 
                 A final response 
                 (ANSI) RESPONSE 
               
               
                 200 OK 
                 indicating session 
                 (ITU-T) END 
               
               
                   
                 has completed 
               
               
                   
                 successfully 
               
               
                 4xx Client Error 
                 The request 
                 used to indicate 
               
               
                   
                 contains bad 
                 problems with TCAP 
               
               
                   
                 syntax or cannot 
                 encoding in the SIP 
               
               
                   
                 be fulfilled at 
                 message 
               
               
                   
                 this server 
               
               
                 5xx Server Error 
                 The server failed 
                 used to indicate 
               
               
                   
                 to fulfill an 
                 problems with TCAP 
               
               
                   
                 apparently valid 
                 encoding in the SIP 
               
               
                   
                 request 
                 message 
               
               
                   
               
             
          
         
       
     
     Using the above mappings, SIP request/response transactions performing the functional equivalent of legacy TCAP query/response transactions can be accomplished.  FIGS. 3   a – 5   b  show message flows for three exemplary transactions, under TCAP and SIP. 
       FIG. 3   a  shows principle steps of a TCAP query/response transaction according to the prior art. As shown in  FIG. 3   a,  an SSP forwards a TCAP-Query with Permission (QwP) to an SCP (at step S 2 ), which responds by returning a TCAP-Response to the SSP (at step S 4 ). The functional equivalent of this transaction, using SIP in accordance with the present invention is illustrated in  FIG. 3   b . Thus a SIP-Invite message encapsulating the content (e.g. dialed digits) of the TCAP-QwP message is forwarded by an MGC  16  to the AS  18  (at step S 6 ), which responds, first with a SIP-Ack message (step S 8 ), and then, subsequently, a SIP-200 OK message (step S 10 ) encapsulating the content of the TCAP-Response message (e.g. analyzed route information). 
       FIG. 4   a  shows principle steps of a “send to resource” conversation according to the prior art. As shown in  FIG. 4   a,  an SSP forwards a TCAP-Query with Permission (QwP) to an SCP (at step S 12 ), which responds by returning a TCAP-Response (send to resource) to the SSP (step S 14 ). Based on the content of the TCAP-Response message, the SSP sets up a connection to an Intelligent Peripheral (IPe) (step S 16 ), which can then perform various functions, such as playing an announcement (step S 18 ), and/or collecting dialed digits (step S 20 ). The IPe then forwards a Facility message (step S 22 ) containing the results of its processing (e.g. dialed digits) to the SSP, which in turn forwards this data to the SCP in a TCAP-CwP (Call Information From Resource (CIFR)) message to the SCP (step S 24 ). The SCP returns a TCAP-CwP (Call Information To Resource (CITR)) message to the SSP (step S 26 ), which in turn forwards a Facility message containing the CITR information to the Intelligent Peripheral (step S 28 ). The Intelligent Peripheral then sends a Release message to the SSP (step S 30 ) to release the connection between the SSP and the IPe. Upon receipt of the Release message, the SSP sends a TCAP-CwP message indicating that the resource is clear to the SCP (step S 32 ), which returns a TCAP-Response message to the SSP (step S 34 ). As described above, the messages exchanged between the SCP and the SSP are TCAP messages. Conversely, messages exchanged between the SSP and the intelligent peripheral would normally be Private Rate Interface (PRI) protocol messages, conveyed over an Integrated Services Digital Network (ISDN) or ethernet link. 
       FIG. 4   b  illustrates the equivalent “send to resource” transaction using SIP encapsulating TCAP in accordance with the present invention. As shown in  FIG. 4   b,  an MGC  16  forwards a SIP-Invite message encapsulating the content of the TCAP-QwP message to the AS  18  (at step S 36 ), which responds by returning first a SIP-Ack (step S 38 ) and then a SIP-182 Queued message encapsulating the content of a TCAP “send to resource” message to the MGC  16  (step S 40 ). Based on the content of the SIP-182 Queued message, the MGC  16  sets up a connection to an Intelligent Peripheral (Ipe) (step S 42 ), which then performs various functions, such as playing an announcement (step S 44 ) and/or collecting dialed digits (step S 46 ). The Intelligent Peripheral then forwards a Facility message containing the results of its processing (e.g. dialed digits) to the MGC  16  (step S 48 ), which in turn forwards this data to the AS  18  in a SIP-182 Queued message (step S 50 ). The AS  18  returns a SIP-182 Queued message containing Circuit Information To Resource (CITR) information to the MGC  16  (step S 52 ), which in turn forwards a Facility message containing the CITR information to the Intelligent Peripheral (step S 54 ). The Intelligent Peripheral then sends a Release message to the MGC  16  (step S 56 ) to release the connection between the MGC  16  and the IPe. Upon receipt of the Release message, the MGC  16  sends a SIP-182 Queued message indicating that the resource is clear to the AS  18  (step S 58 ), which returns a SIP-200 OK message to the MGC  16  (step S 60 ). As described above in respect of  FIG. 4   a,  the signals between the MGC  16  and the intelligent peripheral would normally be in Private Rate Interface (PRI) messages, and may be conveyed over an Integrated Services Digital Network (ISDN) or ethernet link. 
       FIG. 5   a  shows principle TCAP messages exchanged in a prior art Ring AGain (RAG) transaction. As shown in  FIG. 5   a,  an attempt by a calling party to establish a telephone connection between phone A and a called party at phone B results in conventional ISUP-IAM messaging between SSP-A and SSP-B (step S 62 ), which detects phone B in use (off hook) and therefore returns a conventional ISUP-Rel message to SSP-A (step S 64 ). Upon receipt of the “busy” signal, the calling party activates the RAG feature and places phone A on-hook (step S 66 ). As a result, SSP-A forwards a TCAP-QwP (NRAG) message to SSP-B (step S 68 ), which responds with a TCAP-CwP message acknowledging the TCAP-QwP (NRAG) message (step S 70 ). When the called party places phone B on-hook (step S 72 ), SSP-B forwards a TCAP-CwP message to SSP-A (step S 74 ), which responds with a TCAP (NRAG complete) message (step S 76 ). SSP-A can then notify the calling party that the called party is now free (messaging not shown). 
       FIG. 5   b  illustrates the equivalent Ring AGain (RAG) transaction using SIP encapsulating TCAP in accordance with the present invention. As shown in  FIG. 5   b,  an attempt by a calling party to establish a telephone connection between phone A and a called party at phone B results in conventional SIP and/or SIP encapsulating ISUP messaging between MGC-A  16   a  and MGC-B  16   b  (step S 78 ), which detects phone B in use (off hook) and therefore returns a conventional SIP (release) message to MGC-A  16   a  (step S 80 ). Upon receipt of the “busy” signal, the calling party activates the RAG feature (step S 82 ) and places phone A on-hook. As a result, MGC-A  16   a  forwards a SIP-Invite message encapsulating the content of the TCAP-QwP (NRAG) message to MGC-B  16   b  (step S 84 ), which responds, first with a SIP-Ack message (step S 86 ), and then with a SIP-182 Queued message (step S 88 ) acknowledging the SIP-Invite message. When the called party places phone B on-hook (step S 90 ), MGC-B  16   b  forwards a SIP-182 Queued message to MGC-A  16   a  (step S 92 ), which responds with a SIP-200 OK message (step S 94 ). MGC-A  16   a  will then notify the calling party that the called party is now free (messaging not illustrated). 
       FIG. 6  is a block diagram schematically illustrating an exemplary model for a SIP envelope  20  encapsulating TCAP functional content in accordance with an embodiment of the present invention. In the embodiment of  FIG. 6 , the SIP envelope  20  contains identification information in a SIP header  22 , along with a Multipurpose Internet Mail Extension (MIME) part  24 , which includes Session Description Protocol (SDP) description information  26  and a TCAP binary message part  28 , separated by unique boundaries. The SIP envelope can be transported through the broadband packet network  14  using, for example, User Datagram Packet (UDP) protocol over IP. 
     The SIP header  22  and SDP part  26  provide for session control, while the MIME ports  24  provide a description language which adds differing file types to the SIP envelope  20 . Each of these parts share the following attributes:
         they are text-based (ASCII or ISO 10646);   each is used for a specific, unique purpose;   they can carry and/or encode information for that purpose; and   each is implemented following a distinct set of rules.       

     As is known in the art, SIP is an application-layer control protocol for creating, modifying and terminating sessions between two or more devices. For the purposes of encapsulating TCAP functional content in accordance with the present invention, SIP clients are used to communicate transaction information that may result in user agent behaviour. Table 3 below presents exemplary SIP header  22  field definitions and example values that may be used in the context of the present invention. For a basic level of session control, the SIP header  22  may include the ‘From’, ‘To’, ‘Call-ID’, ‘Content-Type’ and ‘Content-Length’ fields. Other known SIP header fields may be utilized, in a known manner, to provide an enhanced level of session control. 
     
       
         
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                 Field 
                 Field definition 
                 Accepted values 
               
               
                   
               
             
             
               
                 From: 
                 address of the 
                 username/machine ID and/or 
               
               
                   
                 “originating” machine 
                 IP address 
               
               
                 To: 
                 address of the 
                 username/machine ID and/or 
               
               
                   
                 “destination” machine 
                 IP address 
               
               
                 Call-ID: 
                 Uniquely identifies 
                 any combination of: 
               
               
                   
                 an invitation or all 
                 the unique call number; 
               
               
                   
                 registrations of a 
                 time-stamp; and 
               
               
                   
                 particular client, 
                 originating/terminating 
               
               
                   
                   
                 SIP Call Server. 
               
               
                 Content- 
                 Indicates the type of 
                 Any of: 
               
               
                 Type: 
                 material to follow. 
                 ‘application/multipart’ 
               
               
                   
                   
                 ‘application/sdp’, 
               
               
                   
                   
                 ‘text/html’ etc. 
               
               
                 Content 
                 Indicates the length 
                 Set to the size of the 
               
               
                 Length 
                 of the following 
                 MIME, SDP and TCAP data 
               
               
                   
                 data, the length of 
                 attached to the SIP 
               
               
                   
                 the message body 
                 header. 
               
               
                   
               
             
          
         
       
     
     Using the above field definitions, an exemplary SIP header  22  for use in the present invention is as follows:
     INVITE sip:callserverA@sipserver.nortelnetworks.com SIP/2.0   From: sip:callserverA@sipserver.nortelnetworks.com   To: sip:appserver123@sipserver.nortelnetworks.com   Call-ID: 1998122516401234@callserverA.nortelnetworks.com   Content-Type: Application/Multipart   Content-Length: 273   

     As its name suggests, the SDP part  26  is used to handle description information for a communications session (e.g. between the MGC  16  and the AS  18 ). The SDP part  26  provides endpoint and connection information, and is identified within the SIP header  22  by a Content-Type field statement of the form: 
     Content-Type: application/SDP; charset: ISO-10646. 
     Exemplary field definitions and contents of the SDP part  26  are provided in Table 4 below. 
     
       
         
               
               
               
             
           
               
                 TABLE 4 
               
               
                   
               
               
                 Field 
                 Description 
                 Example values 
               
               
                   
               
             
             
               
                 v 
                 Version: 
                 protocol version number 
               
               
                 o 
                 Origin: owner or 
                 o = &lt;username&gt;&lt;session 
               
               
                   
                 creator and session 
                 id&gt;&lt;version&gt; &lt;network 
               
               
                   
                 identifier 
                 type&gt;&lt;address type&gt;&lt;address&gt; 
               
               
                   
                 The value of this 
                 &lt;username&gt; is preferably the 
               
               
                   
                 field must uniquely 
                 Calling Party from the SCCP 
               
               
                   
                 identify the session 
                 global title. 
               
               
                 s 
                 Session Name: 
                 A text description 
               
               
                 m 
                 Media Description: 
                 m = &lt;media&gt; &lt;port&gt; &lt;transport&gt; 
               
               
                   
                 Name and Transport 
                 &lt;fmt list&gt; 
               
               
                   
                 address 
                 &lt;media&gt; may be any of 
               
               
                   
                   
                 “audio”, “video”, 
               
               
                   
                   
                 “application”, “data” or 
               
               
                   
                   
                 “control“ 
               
               
                 c 
                 Connection Data 
                 ‘IN’ (Internet) followed by 
               
               
                   
                 This is an optional 
                 the ‘IP4’ (identifying the 
               
               
                   
                 field 
                 IP version 4 method of IP 
               
               
                   
                   
                 address ID) followed by the 
               
               
                   
                   
                 connection IP address. 
               
               
                   
                   
                 Other variations exist, 
               
               
                   
                   
                 including TTL information 
               
               
                   
                   
                 for multicast addresses. 
               
               
                 e, p 
                 Email Address and 
                 This field may be used to 
               
               
                   
                 Phone Number 
                 reflect the Calling Party 
               
               
                   
                 e = &lt;email address&gt; 
                 address from the SCCP global 
               
               
                   
                 p = &lt;phone number&gt; 
                 title address. 
               
               
                   
                 These fields specify 
               
               
                   
                 contact information of 
               
               
                   
                 the person responsible 
               
               
                   
                 for the Conference. 
               
               
                   
                 This may not Be the 
               
               
                   
                 initiator of the 
               
               
                   
                 session. 
               
               
                   
                 These are an optional 
               
               
                   
                 field 
               
               
                   
               
             
          
         
       
     
     Using the above field definitions, an exemplary SDP port  26  for use in the present invention is as follows.
     --unique-boundary-1-   Content-Type: application/multipart; charset=ISO-10646
       v=0   o=jnicoletta 2890844526 2890842807 IN IP4 126.16.64.4   s=SDP seminar   c=IN IP4 MGCX.nortelnetworks.com   p=+1 613 722 1000   m=application/TCAP 9092 udp 0 3 4   
       

     As is known in the art, MIME was originally designed to attach files to email messages, but can be readily adapted for use in other transport systems. For the purposes of the present invention, the MIME part  24  is used to attach the TCAP binary message part  28  to the end of the SIP/SDP combination. MIME multipart payloads enable a SIP envelope  20  to carry any PSTN/CCS signaling information required to invoke IN/AIN functionality. The multipart body can consist of any combination of: SDP payload; TCAP payload; and/or any number of MIME types. 
     TCAP can contain multiple components. In accordance with the present invention, it is possible to encapsulate a multipart TCAP message in one MIME payload, or alternatively to encapsulate each TCAP component in a respective individual MIME payload. In general, the MIME header  30  follows the SIP header  22 , and will take the form of the following exemplary MIME header:
     MIME-Version: 1.0   Content-Type: multipart/mixed; boundary=unique-boundary-1   

     An exemplary MIME payload  28  carrying TCAP binary message payload in accordance with the present invention is as follows:
     --unique-boundary-1
       Content-type:application/TCAP;version=0;base=ansi88   Content-Transfer-Encoding: binary   89 8b 0e 95 1e 1e 1e 06 26 05 0d f5 01 06 10 04 00   
       --unique-boundary-1-   

     The above described mappings enable the functional content of TCAP messages to be encapsulated within SIP envelopes  20  for transport through a broadband packet network  14 . The encapsulation of TCAP functional content will now be further described by way of three exemplary SIP messages as follows: a SIP-INVITE message encapsulating a TCAP Query; a SIP-182 Queued message encapsulating a TCAP Conversation with Permission message; and a SIP-200 OK message encapsulating a TCAP response message. 
     The SIP message format requires the first line to be a ‘Request’ line, followed by a series of ‘Header’ lines, a &lt;CRLF&gt; separator, and, lastly, the message body. In the present example, the SDP Part  26  and MIME payload  28  are separated by a boundary parameter which, for this example, has the value of “unique-boundary-1”.
     INVITE sip:callserverA@sipserver.nortelnetworks.com SIP/2.0   From: sip:callserverA@sipserver.nortelnetworks.com   To: sip:appserver123@sipserver.nortelnetworks.com   Call-ID: 1998122516401234@callserverA.nortelnetworks.com   Content-Type: Application/Multipart   Content-Length: 273   MIME-Version: 1.0   Content-Type: multipart/mixed; boundary=unique-boundary-1   21 CRLF&gt;   -unique-boundary-1   Content-Type: application/SDP; charset=ISO-10646   v=0   o=markbos 1234567890 1234567890 IN IP4 190.3.109.6   s=SDP seminar   c=IN IP4 confserver.nortelnetworks.com   t=234567890 1234567890   p=+1 613 722 1000   m=application 9092 UDP 0 3 4   --unique-boundary-1   Content-type:application/TCAP;version=0;base=ansi88   Content-Transfer-Encoding: binary   89 8b 0e 95 1e 1e 1e 06 26 05 0d f5 01 06 10 04 00   --unique-boundary-1-   

       FIGS. 3   b,    4   b  and  5   b  illustrate the use of SIP-182 Queued messages for encapsulating the functional content of TCAP Conversation with Permission messages. An exemplary SIP-182 Queued message usable for this purpose is as follows:
     SIP[TCAP]/0.0 182 Queued   From: callserverB &lt;sip:callserverB.nortelnetworks.com&gt;   To: callserverA &lt;sip:callserverA.nortelnetworks.com&gt;   Call-ID: 1998122516401234@callserverB.nortelnetworks.com   Content-Length: 122   Cseq: 1   MIME-Version: 1.0   Content-Type: application/tcap;base=ansi92   Content-Transfer-Encoding: binary
       &lt;TCAP Binary message part encoded here&gt;   
       
       FIGS. 3   b,    4   b  and  5   b  also illustrate the use of SIP-200 OK messages for encapsulating the functional content of TCAP response messages. An exemplary SIP-200 OK message usable for this purpose is as follows:
     SIP[TCAP]/0.0 200 OK   From: callserverA &lt;sip:me.nortelnetworks.com&gt;   To: callserverB &lt;sip:callserverB.nrtelnetworks.com&gt;   Call-ID: 1998122516401234@callserverB.nortelnetworks.com   CSeq: 2 BYE   MIME-Version: 1.0   Content-Type: application/tcap;base=ansi92   Content-Transfer-Encoding: binary
       &lt;TCAP Binary message part encoded here&gt;   
       
     The embodiment(s) of the invention described above is(are) intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.