User equipment timestamps for offline charging in IMS networks
View Patent ↗Communication networks and associated methods are disclosed that provide offline charging in IMS networks. One of the methods includes receiving call signaling for a call from an access network serving user equipment for the call. The call signaling includes an access network identifier for the access network. The method further includes identifying location information related to the access network identifier. The method further includes determining a local time for the user equipment based on the location information. The method further includes generating a charging message for the call, and inserting a timestamp in the charging message based on the local time for the user equipment. The timestamp in the charging message provides the billing system with the local time for the user equipment to allow for variable-rate billing.
1. A system comprising:
a Serving-Call Session Control Function (S-CSCF) for an IP Multimedia Subsystem (IMS) core network that is configured to:
receive a session-related message for user equipment (UE) from an access network that is serving the UE, wherein the session-related message includes an identifier for the access network that provides service to the UE for accessing the IMS core network;
identify location information related to the access network identifier in the session-related message;
determine a time zone where the UE is located based on the location information;
identify a local time for the S-CSCF based on an internal clock;
adjust the local time for the S-CSCF based on the time zone of the UE to determine a local time for the UE;
generate a Diameter charging message for the session;
insert a timestamp in an Attribute Value Pair (AVP) of the Diameter charging message based on the local time for the UE; and
transmit the Diameter charging message to an offline charging function.
2. The system of claim 1 wherein:
the access network identifier is inserted in the session-related message by the UE.
3. The system of claim 1 wherein:
the Diameter charging message comprises a Diameter Accounting Request (ACR).
4. The system of claim 1 wherein:
the access network identifier is inserted in the session-related message by the access network.
5. The system of claim 1 wherein:
the S-CSCF is configured to query a location server based on the network access identifier to identify the location information.
6. The system of claim 1 wherein:
the access network identifier comprise a MAC address of an access point in the access network.
7. The system of claim 1 wherein:
the session-related message comprises a Session Initiation Protocol (SIP) message that includes the access network identifier.
8. A method comprising:
receiving, in a Serving-Call Session Control Function (S-CSCF) of an IP Multimedia Subsystem (IMS) core network, a session-related message for user equipment (UE) from an access network that is serving the UE, wherein the session-related message includes an identifier for the access network that provides service to the UE for accessing the IMS core network;
identifying location information in the S-CSCF that is related to the access network identifier in the session-related message;
determining, in the S-CSCF, a time zone where the UE is located based on the location information;
identifying a local time for the S-CSCF based on an internal clock;
adjusting the local time for the S-CSCF based on the time zone of the UE to determine a local time for the UE;
generating a Diameter charging message for the session;
inserting a timestamp in an Attribute Value Pair (AVP) of the Diameter charging message based on the local time for the UE; and
transmitting the Diameter charging message from the S-CSCF to an offline charging function.
9. The method of claim 8 wherein:
the Diameter charging message comprises a Diameter Accounting Request (ACR).
10. The method of claim 8 wherein identifying location information related to the access network identifier comprises:
querying a location server with the S-CSCF based on the network access identifier to identify the location information.
11. The method of claim 8 wherein:
the access network identifier comprise a MAC address of an access point in the access network.
12. The method of claim 8 wherein:
the access network identifier is inserted in the session-related message by the UE.
13. A system comprising:
an offline charging server configured to receive a Diameter charging message from a node of an IP Multimedia Subsystem (IMS) core network, and to process the Diameter charging message to identify an access network identifier in an Attribute Value Pair (AVP) of the Diameter charging message, wherein the access network identifier comprises data that indicates an access network that provides service to the UE for accessing the IMS core network;
the offline charging server is configured to identify location information related to the access network identifier in the Diameter charging message, to determine a time zone where the UE is located based on the location information, to identify a local time for the offline charging server based on an internal clock, to adjust the local time for the offline charging server based on the time zone of the UE to determine a local time for the UE, to
generate a Charging Data Record (CDR) for the session, to insert a timestamp in the CDR based on the local time for the UE, and to transmit the CDR to a billing system.
14. The system of claim 13 wherein:
the Diameter charging message comprises a Diameter Accounting Request (ACR) message.
15. The system of claim 13 wherein:
the offline charging server is configured to query a location server based on the network access identifier to identify the location information.
16. The system of claim 13 wherein:
the access network identifier comprise a MAC address of an access point in the access network.
17. The system of claim 13 wherein:
the offline charging server includes a Charging Data Function (CDF) and a Charging Gateway Function (CGF).