Description

Title

Providing charging related information in a communication system

Technical field of the invention

The invention relates to a method, a subscriber database, a control function, an application sever, a computer program product and a system for providing charging related information in a communication system.

Background of the invention

Within the IP (Internet Protocol) Multimedia Subsystem (IMS) as defined by 3 ^rd Generation Partnership Project (3GPP) Session Initiation Protocol (SIP) defined by Internet Engineering Task Force (IETF) is used for controlling communication. SIP is an application-layer control protocol for creating, modifying, and terminating sessions with one or more participants. These sessions may include Internet multimedia conferences, Internet telephone calls, and multimedia distribution. Members in a session can communicate via multicast or via a mesh of unicast relations, or a combination of these. IMS charging is being specified in 3GPP specification TS 32.260 and IP multimedia call control in general in TS 24.229.

An Advice of Charge (AoC) supplementary service used in communication systems announces the tariff/rate/cost of the requested service e.g. a phone call to the user,

either the expected rate before connecting the call, during the call the cumulated costs, or after the call the total costs. The AoC allows the user to terminate the service before costs emerge to the user. This service is required by many regulators for cost transparency reasons. Currently, in the 3GPP standardisation body the standardisation of the AoC service is ongoing and will be specified in TS 32.280.

Currently, in many public switched telephone network

(PSTN) and public land mobile network (PLMN) telephony networks the AoC service is offered, for example as announcements for premium rate services "This call costs you 2 Euro a minute...". In the future the regulators can request the AoC service also for voice over internet protocol (VoIP) phone calls either, e.g. calls switched via the IMS or other IMS services.

At the time being, the AoC service is requested by many operators in tenders for both user comfort and to fulfill expected regulatory issues.

Within 3GPP circuit switched (CS) and packet switched (PS) mobile networks different methods exist to differentiate for several charging criteria. Further solutions exist to indicate (CAMEL based) online charging. However, no solution for IMS based networks exists for further differentiation. Especially with introduction of AoC service support in IMS there has emerged a need for more detailed specification of charging services applied to a subscriber.

Therefore, the object of the invention is to provide a solution for a detailed charging feature specification in IMS based networks .

Summary of the invention

The present invention overcomes the above problem by providing a subscriber database and a method comprising storing charging related information in a subscriber database and providing charging related information to a first network element from the subscriber database. According to another aspect of the invention, the subscriber database and the method further provide receiving a user specific request from the first network element .

According to further refinements of the invention as defined under the above aspect: The storing comprises storing charging related information as a part of user profile in a subscriber database, and the providing comprises providing charging related information as a part of user profile information. The providing comprises providing the charging related information as an attribute value pair, providing the charging related information via Cx interface of an internet protocol multimedia subsystem, providing the charging related information as part of a user profile download operation, providing the charging related information while user registration in an internet protocol multimedia subsystem, and providing the charging related information via Sh interface of an internet protocol multimedia subsystem. The sending comprises sending charging related information from the

first network element to a second network element. The first network element comprises a call state control function in an internet protocol multimedia subsystem or an application server and the second network element comprises an application server, and the application server comprises an advice of charge application server or an internet protocol multimedia subsystem gateway function. The charging related information is sent in a header of a session initiation protocol message or in a P-Charging-Vector header. The subscriber database comprises a home subscriber server of an internet protocol multimedia subsystem or an authentication, authorization, and accounting server. The charging related information comprises charging specific settings for a user, settings list for offline charged user, a service list for online charged user, a charging address entry, or common charging settings. The charging address entry includes at least one of a charging collection function address for offline charging and an event charging function address for online charging. The settings list for offline charged users includes at least one of rating information, time interval, volume interval, budget control information, and FTP push host address. The service list for online charged users includes at least one of budget control information, type of advice of charge service, and rating information. The budget control information includes at least one of an indication of pre-paid service or an indication of cost limit supervision. The rating information includes an indication of whether centralized or de-centralized rating should be used for the user.

The invention further provides a control function and a method comprising requesting means for requesting charging related information from a subscriber database, and receiving means for receiving charging related information from the subscriber database. According to another aspect of the invention, the control function and the method further comprise sending means for sending charging related information to an application server.

According to further refinements of the invention as defined under the above aspect:

The control function comprises a call state control function in an internet protocol multimedia subsystem. The requesting means and the receiving means are configured to request and receive the charging related information via Cx interface of an internet protocol multimedia subsystem. The receiving charging related information comprises receiving charging related information as part of a user profile download operation. The application server comprises an advice of charge application server or an internet protocol multimedia subsystem gateway function. The charging related information includes at least one of a settings list for offline charged user, a service list for online charged user, a charging address entry, and common charging settings. The charging address entry includes at least one of a charging collection function address for offline charging and an event charging function address for online charging. The settings list for offline charged users includes at least one of

rating information, time interval, volume interval, budget control information, and FTP push host address. The service list for online charged users includes at least one of budget control information, type of advice of charge service, and rating information. The budget control information includes at least one of an indication of pre-paid service or an indication of cost limit supervision. The rating information includes an indication of whether centralized or de-centralized rating should be used for the user.

The invention further provides an application server and a method in a communication communication system, comprising receiving means for receiving charging related information. According to another aspect of the invention, the application server and the method further comprise requesting means for requesting charging related information from a subscriber database or from a control function.

According to further refinements of the invention as defined under the above aspect: The receiving means comprise receiving means for receiving charging related information from a control function, for receiving charging related information in a header of a session initiation protocol message, or in a P-Charging-Vector header. The requesting means and the receiving means are configured to request and receive the charging related information via Sh interface of an internet protocol multimedia subsystem. The application server comprises a session initiation protocol application server, an advice of charge application server or an internet protocol multimedia subsystem

gateway function. The charging related information includes at least one of a settings list for offline charged user, a service list for online charged user, a charging address entry, and common charging settings.

The invention further provides a computer program product comprising code means adapted to produce the steps of any one of methods described above when loaded into the memory of a computer.

The invention further provides a system comprising at least one of a subscriber database, a control function and an application server as described above.

The present invention has the advantage that detailed specification of charging services applied to a subscriber can be provided within a communication network, such as IMS.

Brief description of drawings :

Embodiments of the present invention are described herein below with reference to the accompanying drawings, wherein:

Figure 1 illustrates IMS charging architecture relevant for the invention.

Figure 2 illustrates interfaces and information flows within relevant network elements of the invention. Figures 3-7 illustrate example signaling flows for providing charging related information according to embodiments of the invention.

Figure 8 explains internal structures of a subscriber database, a control function and an application server (AS) according to embodiments of the invention. Figures 9 and 10 show methods according to embodiments of the invention.

Detailed description of the invention

Different types of network entities and functions exist in the IMS network. Call Session Control Functions (CSCF) implement a session control function in SIP layer. The CSCF can act as Proxy CSCF (P-CSCF), Serving CSCF (S-CSCF) or Interrogating CSCF (I-CSCF) . The P-CSCF is the first contact point for the User Equipment (UE) within the IMS; the S-CSCF actually handles the session states in the network; the I-CSCF is mainly the contact point within an operator's network for all IMS connections destined to a subscriber of that network operator, or a roaming subscriber currently located within that network operator's service area.

The functions performed by the I-CSCF are, for example, assigning an S-CSCF to a user performing SIP registration and routing SIP requests received from another network towards the S-CSCF. The S-CSCF performs the session control services for the UE. It maintains a session state as needed by the network operator for support of the services and may be acting as registrar, i.e. it accepts registration requests and makes its information available through a location server. The S- CSCF is the central point to users that are hosted by this S-CSCF. The S-CSCF provides services to registered and unregistered users when it is assigned to these

users. This assignment is stored in the Home Subscriber Server (HSS) .

The HSS is the master database for a given user. It is the entity containing the subscription-related information to support the network entities actually handling calls/sessions. As an example, the HSS provides support to the call control servers (CSCFs) in order to complete the routing/roaming procedures by solving authentication, authorization, naming/addressing resolution, location dependencies, etc. For IMS a certain service is typically assigned to a subscriber by a filter criteria within its HSS data set, this filter criteria forces a serving CSCF of a certain subscriber to route SIP messages that belongs to this subscriber and service via a SIP application servers (SIP-AS) that matches to this filter criteria.

The HSS is responsible for holding for example the following user related information:

User Identification, Numbering and addressing information

User Security information: Network access control information for authentication and authorization, such as password information

User Location information at inter-system level: the HSS supports the user registration, and stores inter-system location information, etc.

User profile information.

Cx reference point or Cx interface is an interface between a CSCF and a HSS, supporting the transfer of data between them. The Cx reference point is based on the diameter protocol with 3GPP standard diameter

applications. Sh interface is a corresponding interface between the HSS and an application server (AS) . Diameter is an authentication, authorisation, and accounting (AAA) protocol defined by the IETF and used for network access services, such as dial-up and mobile IP.

An application server (AS) is offering value added IP multimedia (IM) services to users of the IMS network and resides either in the IMS user's home network or in a third party location. The third party could be a network or simply a stand-alone AS. The AS may host and execute various services and can influence and impact a SIP session on behalf of the services. The IP multimedia Subsystem Service Control Interface (ISC) interface is between the S-CSCF and the service platforms (i.e. ASs). The ISC interface offers extended services to subscribers. ASs that are connected to the IMS are controlled via ISC interface. The protocol used on the ISC interface is the SIP. Examples of an AS include e.g. AoC AS or AoC function and IMS-gateway function (IMS- GWF) .

An HSS can communicate with an application server over Sh interface. The Sh interface enables data handling procedures, for example, download of data from the HSS to an AS, or update of data in the HSS.

An AS can subscribe to receive notifications from the

HSS of changes in data. The HSS can notify an AS of changes in data for which the AS previously had subscribed. Diameter protocol can be used in Sh interface .

Charging is a function within the telecommunications network and the associated charging elements whereby information related to a chargeable event is collected, formatted, transferred and evaluated in order to make it possible to determine usage for which the charged party may be billed (offline charging) or the subscribers account balance may be debited

(online charging). Offline charging is applied to users who pay for their services periodically (e.g., at the end of the month). Online charging, also known as credit-based charging, is used for prepaid services, or real-time credit control of postpaid services. Both may be applied to the same session.

In offline charging, all the SIP network entities involved in the session can use the Diameter Rf interface to send accounting information to a Charging Collector Function (CCF) located in the same domain. The CCF can collect all this information, and build a Call Detail Record (CDR) , which can sent to the billing system (BS) of the domain. Each session can carry an IMS Charging Identifier (ICID) as a unique identifier. Inter Operator Identifier (IOI) parameters define the originating and terminating networks. Each domain can have its own charging network. Billing systems in different domains can also exchange information, so that roaming charges can be applied.

In online charging, the S-CSCF can communicate with a Session Charging Function (SCF) which looks like a regular SIP application server. The SCF can signal the S-CSCF to terminate the session when the user runs out of credits during a session. The AS and MRFC can use the Diameter Ro interface towards an Event Charging Function (ECF) . When Immediate Event Charging (IEC) is used, a number of credit units can immediately be deducted from the user's account by the ECF and the MRFC or AS is then authorized to provide the service. The service may not

be authorized when not enough credit units are available. When Event Charging with Unit Reservation (ECUR) is used, the ECF can first reserve a number of credit units in the user's account and then authorizes the MRFC or the AS. After the service is over, the number of spent credit units can be reported and deducted from the account; the reserved credit units are then cleared.

An Advice of Charge (AoC) supplementary service used in communication systems announces the tariff/rate/cost of the requested service e.g. a phone call to the user, either the expected rate before connecting the call, during the call the cumulated costs, or after the call the total costs. The AoC allows the user to terminate the service before costs emerge to the user.

Three types of AOC service exist: a) Charging information at communication set-up time (AOC-S)

The AOC-S service enables a user to receive information about the charging rates at communication set-up time and also to receive further information during the communication if there is a change of charging rates. b) Charging information during the communication (AOC- D)

The AOC-D service enables a user to receive information on the recorded charges for a communication during the active phase of the communication. c) Charging information at the end of the communication (AOC-E)

The AOC-E service enables a user to receive information on the recorded charges for a communication when the communication is terminated.

Fig. 1 is an overview of another structure to which embodiments of the present invention are applicable. Fig. 1 shows the specific parts of an IMS charging architecture that handles AoC and other charging information according to embodiments of the invention. Fig.1 shows also functional entities that are not directly involved in the present invention, for the sake of completeness.

The IMS charging architecture as shown in Fig. 1 comprises a Billing Domain, a charging collection function CCF involved with offline charging including a charging gateway function CGF and a charging data function CDF, a used equipment UE, a Proxy call session control function P-CSCF, a serving call session control function S-CSCF, and a home subscriber server HSS. The HSS stores filter criteria, in particular initial filter criteria (iFC) set for the users or UEs assigned to the respective HSS. The filter criteria determine the services that will be provided to each user. The architecture further comprises an IMS-GWF, online charging system OCS, an AoC function, and an interconnect border control function IBCF. The architecture in Fig. 1 also shows another application server AS.

PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described herein below with reference to the accompanying drawings.

In embodiments of the invention, detailed charging related information can be stored as a part of user profile in a subscriber database, such as an AAA server or a HSS, and a control function or an application server receives the charging related information from the subscriber database. The AAA server is a server that

handles user requests for access to computer resources and provides authentication, authorization, and accounting services. The AAA server can interact with network access and gateway servers and with databases and directories that contain user information. Devices and applications typically communicate with an AAA server by using the remote authentication dial-in user service (RADIUS) .

The interfaces and information flows within relevant network elements according to an embodiment of the invention are shown in Figure 2. The SIP AS (e.g. AoC AS or IMS-GWF) is connected via the ISC interface to the S- CSCF and via Sh interface to the HSS. The S-CSCF is connected to the HSS via Cx interface.

According to first embodiment of the invention a method is provided in which detailed charging related information is stored in a subscriber server and provided to a network element. The method provides separated indication of certain charging settings for online and offline charging services. The detailed charging related information may comprise charging function address for choosing the charging method that shall be applied for the subscriber, wherein an ECF address indicates online charging and a CCF address indicates offline charging. Both methods can be assigned in parallel.

The detailed charging related information may further comprise a list of online charging services, wherein the list may include e.g. budget control, also differentiating between that for prepaid subscribers and that for monthly cost limit supervision of postpaid subscribers (PrePaidService,

CostLimitSupervision), all known types of advice of charge services (for example AoC-S, AoC-D, AoC-E, AOCC, AOCI), information whether for the

user centralized or de-centralized rating shall be performed. The list may be prepared for operator specific use by some extension fields.

The configured service list may be downloaded via Cx query together with the initial filter criteria (iFC) and the charging function addresses to the S- CSCF. Further, the service list may be provided via the Sh interface, if requested by a particular SIP-AS (like the AoC AS). In that way the handling of charging processing while service execution become more flexible and easier to adapt to operators demands: A prepaid service may be combined with a balance check service (i.e. even if there is a budget available for a prepaid account, it shall not exceed a monthly limit), an AoC service may be provided without having a credit request dialog at the online charging interface, and other combinations of the service and the interface may be possible.

The information whether for this user centralized or de-centralized rating shall be performed may be combined with e.g. a SIP method or a SIP-AS. In such a case it is possible to inform e.g. the IMS-GWF whether centralized or de-centralized rating shall be performed for this user when a particular SIP method is used or a specific SIP-AS is used.

The detailed charging related information may further include a service or settings list for offline charger users, wherein the list may include rating information, time interval, volume interval, budget control information, and

FTP push host address. By using subscriber specific FTP-push hosts it is possible to transfer the CDRs generated by e.g. the S-CSCF to a particular FTP host, which is responsible for a specific group of IMS users or in case of IMS hosting, a specific hosted IMS operator.

P-charg ing-vector is a SIP private header which is used to share the charging correlation information among different IP multimedia subsystem (IMS) network elements and between the IMS and the access network. P- charg ing-vector consists of the IMS charging identifier, inter-operator

identifier, and access network charging information. To handle the new charging service related subscriber data entries, the P-Charg ing-Vector header may be extended by new parameters, indicating the relevant charging services and offline settings. By this extension it is for example possible to disable the budget request dialog at the online charging interface (Ro) if no such service entry exists.

The charging specific settings may be assigned to a subscriber within its HSS user profile. The access to charging specific HSS subscriber data entries may be done using the Cx interface while subscriber registration in the CSCF, but also by a SIP-AS using the Sh interface. But especially for the IMS-GW function (as a special SIP-AS that does online charging processing towards the OCS) there is no separate Sh interface defined within 3GPP architecture at the moment. If today an IMS-GWF is involved into a SIP route it assumes the prepaid online charging service and does a

Diameter credit control dialog via Ro interface towards the online charging system (OCS) to force a budget request for the specified service of this subscriber. According to the embodiment of the invention, to indicate any type of online or offline charging settings or services, charging setting indications (e.g. subscribed AoC types, budget control service used, reference to several offline charging settings) are added within the P- Charg ing-Vector header. The current P-Charg ing-Vector header may for example be extended according to the following:

P-Charging-Vector = "P-Charging-Vector" HCOLON icid-value* (SEMI charge-params) charge-params = icid-gen-addr / orig-ioi / term-ioi / ofl / onl / com / generic-param icid-value = "icid-value" EQUAL gen-value

icid-gen-addr = "icid-generated-at" EQUAL host orig-ioi = "orig-ioi" EQUAL gen-value term-ioi = "term-ioi" EQUAL gen-value onl = "online" EQUAL gen- value ofl = "offline" EQUAL gen-value com = "common" EQUAL gen-value

Where OfI' represents offline settings like flat rate or intermediate charge generation at certain timer or volume thresholds, and OnI' represents online settings like AoC types, budget control etc. The P-Charging-Function-

Addresses header remains within the operators trusted domain, thus its values can be agreed on an operator specific demand. An example of such settings is given:

P-Charg ing-Vector: icid-value=1234bc9876e; icid-generated-at=192.0.6.8; orig-ioi=home1.net; offline=900s,100k,bmd-1.operator.net; online=AoCC,AoC-S,PPS; common=INVITE,MESSAGE

For example the following meaning could be agreed: at "ofl" settings: a zero means no offline charge report is required, a numeric value added by 's' is an intermediate timer in seconds, a numeric value added by k or M is an intermediate volume threshold in kilo or mega bytes. At "onl" these strings could be agreed for example:

AoCC = Advice of Charge Charging

AoCI = Advice of Charge Information AoC-S = Advice of Charge at Start of session AoC-D = Advice of Charge During session AoC-E = Advice of Charge at End of session PPS = PrePaid Service

CBC = Credit Balance Check

The extended part of the Charging-Vector header may remain within the operator's domain, i.e. not sent towards the remote parties operator network.

In one aspect of the invention, the filter criteria, the charging function addresses, and the charging related information mentioned above may be downloaded to the S-CSCF from the HSS via Cx query when the subscriber registers at the IMS. According to another aspect of the invention, this information may be sent within SIP signalling messages via ISC interface from the S-CSCF to an AS while 3 ^rd party registration and while SIP service execution (e.g. via SIP:INVITE or SI P:M ESSAGE). The information may be sent within a charging related AVP to e.g. the SIP application servers that are involved into SIP service processing. According to a further aspect of the invention, the information may be provided to an AS directly from the HSS via Sh interface.

The call flows shown in Figures 3-7 illustrate where and how the described charging related information can be exchanged between the involved nodes according to embodiments of the invention. Figure 3 shows how the charging feature information may be transferred from the HSS to the S-CSCF while user registration. Figure 4 shows how an update of the HSS data set may be indicated to the affected S-CSCF. This may not influence any running SIP service. Figure 5 shows how the charging feature information may be sent via SIP from the S-CSCF to affected SIP-AS and may be retrieved by an SIP-AS

directly from the HSS. Figure 6 shows how an update of the HSS data may be signalled to affected SIP-AS. Figure 7 shows how charging information may be transferred to SIP-AS while 3 ^rd party registration.

Fig 8 shows an internal structure of a subscriber database 100, such as AAA server or HSS, according to an embodiment of the invention. The subscriber database can comprise a receiving unit 101 configured to receive a request associated with a user, and a providing unit

105 to provide charging related information to a network element which unit can be configured to receive the request and send the charging parameters via Cx interface or Sh interface of the IMS, for example to/from an CSCF or application server, such as advice of charge application server or IMS-GWF. The charging related information can comprise at least one of settings list for offline charged user, a service list for online charged user, a charging address entry, and common charging settings. The subscriber database can also have a storing unit 103 for storing charging related information. Providing the charging parameters by the providing unit 105 can comprise providing the charging parameters as part of a user profile download operation.

Fig 8 also shows an internal structure of a control function 200, such as S-CSCF, according to an embodiment of the invention. The S- CSCF can comprise a receiving unit 201 configured to receive charging related information from a subscriber database such as HSS or AAA server. . The receiving unit 201 can receive the charging parameters via Cx interface of the IMS, and can be received as part of a user profile download

operation. The S-CSCF can have sending unit 203 configured to send charging related information to a second network element, such as application server (AS) or to send a request to a subscriber database. According to an aspect of the invention, the application server can be a SIP AS such as AoC AS or IMS-GWF. The sending unit 203 can be configured to send the charging related information in SIP signaling messages. In one embodiment of the invention, the charging related information is sent in a P-Charging -Vector header. The charging related information can comprise at least one of settings list for offline charged user, a service list for online charged user, a charging address entry, and common charging settings. The S-CSCF can also comprise a storing unit 205 configured to store charging related data together with user profile information and initial filter criteria (iFC) .

Fig 8 also shows an internal structure of an application server 300, such as SIP AS, for example AoC AS or IMS- GWF according to an embodiment of the invention. The application server can comprise a receiving unit 301. The receiving unit 301 can receive the charging parameters via Sh interface of the IMS from a subscriber database, such as HSS or AAA server. According to an aspect of the invention, the receiving unit can be configured to receive the charging related information in SIP signaling messages from S-CSCF via ISC interface. In one embodiment of the invention, the charging related information is received in a P-Charging -Vector header. The charging related information can comprise at least one of settings list for offline charged user, a service list for online charged user, a charging address entry, and common charging settings. The AS can also comprise

a sending unit 303 configured to send SIP signaling messages .

All units described above may be implemented for example using microprocessors and/or other electrical components and/or by software.

A subscriber database, a control function and an application server may be physically implemented in a switch, router, server or other hardware platform or electronic equipment which can support data transmission and processing tasks, or can be implemented as a component of other existing device.

Figure 9 presents a method of providing charging related information in a communication system according to an embodiment of the invention. The method includes storing 1001 charging related information in a subscriber database such as HSS or AAA server, receiving 1002 a user specific request from a network element such as

CSCF, in particular S-CSCF or AS, in particular AoC AS or IMS-GWF, and providing 1003 charging related information from a subscriber database to the network element. Stroring charging related information can comprise for example pre-configuring the information by an operator or service provider who is controlling the HSS, or downloading the information from a further server .

Figure 10 presents another method of providing charging related information in a communication system according to an embodiment of the invention. The method includes storing 1001 charging related information in a subscriber database such as HSS or AAA server, receiving

1002 a user specific request from a first network element such as CSCF, in particular S-CSCF, providing

1003 charging related information from a subscriber database to the first network element, and sending 1005 charging related information to a second network element such as AS, in particular AoC AS or IMS-GWF, from the first network element. Stroring charging function address can comprise for example pre-configuring the address by an operator or service provider who is controlling the HSS, or downloading the address from a further server.

The invention is not limited to the IMS, but can also be applied in other types of networks providing AoC and having similar type of subscriber entity as in the IMS. In particular the invention is applicable also to fixed networks and fixed mobile convergence (FMC) networks, as well as next generation networks (NGN) . Therefore, the HSS/AAA, the AoC AS, the IMS-GWF and S-CSCF are only used here as examples of possible network elements.

Functions of a subscriber database, a control function and an application server described above may be implemented by code means, as software, and loaded into memory of a computer.