Charging for roaming users in ims networks

Abstract

Communication networks and methods are disclosed for sharing charging information between a home IMS network and a visited IMS network. If a signaling message for a session is received in the visited IMS network, the visited IMS network assigns a visited charging identifier (e.g., ICID), and shares the visited charging identifier with the home IMS network through signaling messages. Similarly, the home IMS network assigns a home charging identifier, and shares the home charging identifier with the visited IMS network through signaling messages. When CDRs are generated in the home IMS network and the visited IMS network, the networks include the home charging identifier and the visited charging identifier in the CDRs so that billing systems may more easily correlate the CDRs from the different IMS networks.

1 . A system comprising:
 a network element of a visited IMS network adapted to receive a first signaling message for a session from a user roaming in the visited IMS network, to identify a visited charging identifier assigned to the session in the visited IMS network, to insert the visited charging identifier in the first signaling message, and to transmit the first signaling message to a home IMS network for the roaming user;   the network element further adapted to receive a second signaling message for the session from the home IMS network, to process the second signaling message to identify a home charging identifier assigned to the session in the home IMS network, to process the second signaling message to identify additional charging information for the session, to insert the home charging identifier, the visited charging identifier, and the additional charging information in a visited charging message for the session, and to transmit the visited charging message to a charging system of the visited IMS network.   
     
     
         2 . The system of  claim 1  wherein:
 the additional charging information includes an access network charging identifier. 
 
     
     
         3 . The system of  claim 1  wherein:
 the additional charging information includes service delivery timestamps. 
 
     
     
         4 . The system of  claim 1  wherein:
 the additional charging information includes inter-operator identifiers (MI). 
 
     
     
         5 . The system of  claim 1  wherein:
 the first signaling message comprises a SIP message; and 
 the network element is further adapted to insert the visited charging identifier in a new AVP defined in a P-Charging-Vector of the SIP message. 
 
     
     
         6 . The system of  claim 1  wherein:
 the second signaling message comprises a SIP message; and 
 the network element is further adapted to process a new AVP defined in a P-Charging-Vector of the SIP message to identify the home charging identifier. 
 
     
     
         7 . The system of  claim 1  wherein:
 the second signaling message comprises a SIP message; and 
 the network element is further adapted to process a new AVP defined in a P-Charging-Vector of the SIP message to identify the additional charging information. 
 
     
     
         8 . The system of  claim 1  wherein:
 the visited charging message comprises a Diameter Accounting Request (ACR); and 
 the network element is further adapted to insert the additional charging information in a new AVP defined in the ACR. 
 
     
     
         9 . The system of  claim 1  wherein:
 the network element comprises a Proxy-Call Session Control Function (P-CSCF) adapted to assign the visited charging identifier to the session. 
 
     
     
         10 . A method of sharing charging information between a home IMS network of a user and a visited IMS network that is providing service for the user that is roaming, the method comprising:
 receiving a first signaling message for a session in a visited network element of the visited IMS network from the roaming user;   identifying a visited charging identifier for the session;   inserting the visited charging identifier in the first signaling message;   transmitting the first signaling message to the home IMS network;   receiving a second signaling message for the session from a home network element in the home IMS network;   processing the second signaling message to identify a home charging identifier assigned to the session in the home IMS network;   processing the second signaling message to identify additional charging information for the session;   inserting the home charging identifier, the visited charging identifier, and the additional charging information in a visited charging message for the session; and   transmitting the visited charging message to a charging system in the visited IMS network.   
     
     
         11 . The method of  claim 10  wherein:
 the additional charging information includes an access network charging identifier. 
 
     
     
         12 . The method of  claim 10  wherein:
 the additional charging information includes service delivery timestamps. 
 
     
     
         13 . The method of  claim 10  wherein:
 the additional charging information includes inter-operator identifiers (MI). 
 
     
     
         14 . The method of  claim 10  wherein:
 the first signaling message comprises a SIP message; and 
 inserting the visited charging identifier in the first signaling message comprises inserting the visited charging identifier in a new AVP defined in a P-Charging-Vector of the SIP message. 
 
     
     
         15 . The method of  claim 10  wherein:
 the second signaling message comprises a SIP message; and 
 processing the second signaling message to identify a home charging identifier comprises processing a new AVP defined in a P-Charging-Vector of the SIP message to identify the home charging identifier. 
 
     
     
         16 . The method of  claim 10  wherein:
 the second signaling message comprises a SIP message; and 
 processing the second signaling message to identify additional charging information comprises processing a new AVP defined in a P-Charging-Vector of the SIP message to identify the additional charging information. 
 
     
     
         17 . The method of  claim 10  wherein:
 the visited charging message comprises a Diameter Accounting Request (ACR); and 
 inserting the additional charging information in a visited charging message comprises inserting the additional charging information in a new AVP defined in the ACR. 
 
     
     
         18 . The method of  claim 10  further comprising:
 assigning the visited charging identifier to the session in a Proxy-Call Session Control Function (P-CSCF) of the visited IMS network. 
 
     
     
         19 . A system comprising:
 a charging system of a visited IMS network adapted to receive a charging message from a network element serving a session involving a user roaming in the visited IMS network, to process the charging message to identify a home charging identifier assigned to the session in a home IMS network for the roaming user, to process the charging message to identify a visited charging identifier assigned to the session in the visited IMS network, and to process the charging message to identify additional charging information for the session;   the charging system is further operable to generate a visited Charging Data Record (CDR) for the session, to insert the home charging identifier, the visited charging identifier, and the additional charging information in the visited CDR, and to transmit the visited CDR to a visited billing system.   
     
     
         20 . The system of  claim 19  wherein:
 the charging message comprises a Diameter Accounting Request (ACR); and 
 the charging system is further adapted to process a new AVP defined in the ACR to identify the additional charging information.