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Title:
DATA RETENTION FOR S8 HOME ROUTED ROAMING
Document Type and Number:
WIPO Patent Application WO/2017/063668
Kind Code:
A1
Abstract:
The present invention provides apparatuses, methods, computer programs, computer program products and computer-readable media regarding data retention for S8 home routed roaming. The present invention comprises receiving a request for initiating a communication session, the request including at least information regarding a calling party, a called party, and information for deriving a communication type, extracting session information related to the communication session from the received request, the extracted session information including at least one of information regarding the calling party, the called party, the communication type and a time when the request is received, and forwarding the session information to a policy and charging rules function.

Inventors:
BELLING THOMAS (DE)
LEIS PETER (DE)
Application Number:
PCT/EP2015/073612
Publication Date:
April 20, 2017
Filing Date:
October 13, 2015
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
NOKIA SOLUTIONS & NETWORKS OY (FI)
International Classes:
H04L29/06
Foreign References:
EP1770915A12007-04-04
US20110302289A12011-12-08
EP2056570A12009-05-06
Other References:
None
Download PDF:
Claims:
CLAIMS

1 . A method for use in a call session control function, comprising:

receiving a request for initiating a communication session, the request including at least information regarding a calling party, a called party, and information for deriving a communication type,

extracting session information related to the communication session from the received request, the extracted session information including at least one of information regarding the calling party, the called party, the communication type and a time when the request is received, and

forwarding the session information to a policy and charging rules function.

2. The method according to claim 1 , wherein

the session information is forwarded to the policy and charging rules function in an authentication request message.

3. The method according to claim 1 or 2, further comprising:

extracting service information from the request and from a session initiation answer message received by the call session control function, and

forwarding the service information to the policy and charging rules function in an authentication request message.

4. The method according to any one of claims 1 to 3, wherein

the session information and the service information is encapsulated in a transparent container, the transparent container being added to an authentication request message forwarded to the policy and charging rules function.

5. The method according to any one of claims 1 to 4, further comprising:

receiving a request for terminating the communication session, and

recording a time when the request for terminating the communication session is received.

6. The method according to claim 5, further comprising: calculating a duration of the communication session based on the time when the request for initiating the communication session is received and the time when the request for terminating the communication session is received.

7. The method according to claim 5 or 6, further comprising:

forwarding the time when the request for terminating the communication session is received or the calculated duration to the policy and charging rules function.

8. The method according to claim 7, wherein

the time or the duration is forwarded to the policy and charging rules function in a session termination request.

9. The method according to claim 8, wherein

the time or the duration is encapsulated in a transparent container, the transparent container being added to the session termination request forwarded to the policy and charging rules function.

10. A method for use in a serving gateway, comprising:

receiving a bearer request message from a packet data network gateway, extracting session information from the bearer request message, the extracted session information including at least one of information regarding a calling party, a called party, and a communication type, and

storing or forwarding the extracted session information.

1 1. The method according to claim 10, further comprising:

recording a first time based on a time when the bearer request message is received or a time indicated in the session information extracted from the bearer request message indicating when a request for initiating a communication session has been received by a call session control function.

12. The method according to claim 10 or 1 1 , further comprising:

receiving a bearer delete message from the packet data network gateway.

13. The method according to claim 12, further comprising: extracting a second time included in the bearer delete message indicating when a request for terminating a communication session has been received by the call session control function, and

calculating a duration of the communication session based on the first time and the second time extracted from the bearer delete message, and

storing or forwarding the calculated duration.

14. The method according to claim 12, further comprising:

recording a second time when the bearer delete message is received, and calculating a duration of the communication session based on the first time and the second time recorded when the bearer delete message is received, and

storing or forwarding the calculated duration.

15. The method according to claim 12, further comprising:

extracting a duration of a communication session from the bearer delete message, and

storing or forwarding the extracted duration.

16. The method according to any one of claims 10 to 15, wherein

the bearer request message is a request for creating a new bearer or a request for modifying an existing bearer.

17. An apparatus for use in a call session control function, comprising:

at least one processor,

and

at least one memory for storing instructions to be executed by the processor, wherein the at least one memory and the instructions are configured to, with the at least one processor, cause the apparatus at least to perform:

receiving a request for initiating a communication session, the request including at least information regarding a calling party, a called party, and information for deriving a communication type,

extracting session information related to the communication session from the received request, the extracted session information including at least one of information regarding the calling party, the called party, the communication type and a time when the request is received, and

forwarding the session information to a policy and charging rules function.

18. The apparatus according to claim 17, wherein

the session information is forwarded to the policy and charging rules function in an authentication request message.

19. The apparatus according to claim 17 or 18, wherein the at least one memory and the instructions are further configured to, with the at least one processor, cause the apparatus at least to perform:

extracting service information from the request and from a session initiation answer message received by the call session control function, and

forwarding the service information to the policy and charging rules function in an authentication request message.

20. The apparatus according to any one of claims 17 to 19, wherein

the session information and the service information is encapsulated in a transparent container, the transparent container being added to an authentication request message forwarded to the policy and charging rules function.

21. The apparatus according to any one of claims 17 to 20, wherein the at least one memory and the instructions are further configured to, with the at least one processor, cause the apparatus at least to perform:

receiving a request for terminating the communication session, and

recording a time when the request for terminating the communication session is received.

22. The apparatus according to claim 21 , wherein the at least one memory and the instructions are further configured to, with the at least one processor, cause the apparatus at least to perform:

calculating a duration of the communication session based on the time when the request for initiating the communication session is received and the time when the request for terminating the communication session is received.

23. The apparatus according to claim 21 or 22, wherein the at least one memory and the instructions are further configured to, with the at least one processor, cause the apparatus at least to perform: forwarding the time when the request for terminating the communication session is received or the calculated duration to the policy and charging rules function.

24. The apparatus according to claim 23, wherein

the time or the duration is forwarded to the policy and charging rules function in a session termination request.

25. The apparatus according to claim 24, wherein

the time or the duration is encapsulated in a transparent container, the transparent container being added to the session termination request forwarded to the policy and charging rules function.

26. An apparatus for use in a serving gateway, comprising:

at least one processor,

and

at least one memory for storing instructions to be executed by the processor, wherein the at least one memory and the instructions are configured to, with the at least one processor, cause the apparatus at least to perform:

receiving a bearer request message from a packet data network gateway, extracting session information from the bearer request message, the extracted session information including at least one of information regarding a calling party, a called party, and a communication type, and

storing or forwarding the extracted session information.

27. The apparatus according to claim 26, wherein the at least one memory and the instructions are further configured to, with the at least one processor, cause the apparatus at least to perform:

recording a first time based on a time when the bearer request message is received or a time indicated in the session information extracted from the bearer request message indicating when a request for initiating a communication session has been received by a call session control function.

28. The apparatus according to claim 26 or 27, wherein the at least one memory and the instructions are further configured to, with the at least one processor, cause the apparatus at least to perform:

receiving a bearer delete message from the packet data network gateway.

29. The apparatus according to claim 28, wherein the at least one memory and the instructions are further configured to, with the at least one processor, cause the apparatus at least to perform:

extracting a second time included in the bearer delete message indicating when a request for terminating a communication session has been received by the call session control function, and

calculating a duration of the communication session based on the first time and the second time extracted from the bearer delete message, and

storing or forwarding the calculated duration.

30. The apparatus according to claim 28, wherein the at least one memory and the instructions are further configured to, with the at least one processor, cause the apparatus at least to perform:

recording a second time when the bearer delete message is received, and calculating a duration of the communication session based on the first time and the second time recorded when the bearer delete message is received, and

storing or forwarding the calculated duration.

31. The apparatus according to claim 28, wherein the at least one memory and the instructions are further configured to, with the at least one processor, cause the apparatus at least to perform:

extracting a duration of a communication session from the bearer delete message, and

storing or forwarding the extracted duration.

32. The apparatus according to any one of claims 26 to 31 , wherein

the bearer request message is a request for creating a new bearer or a request for modifying an existing bearer.

33. A computer program product including a program for a processing device, comprising software code portions for performing the method of any one of claims 1 to 16 when the program is run on the processing device.

34. The computer program product according to claim 33, wherein the computer program product comprises a computer-readable medium on which the software code portions are stored.

35. The computer program product according to claim 33, wherein the program is directly loadable into an internal memory of the processing device.

36. An apparatus, comprising:

means for receiving a request for initiating a communication session, the request including at least information regarding a calling party, a called party, and information for deriving a communication type,

means for extracting session information related to the communication session from the received request, the extracted session information including at least one of information regarding the calling party, the called party, the communication type and a time when the request is received, and

means for forwarding the session information to a policy and charging rules function.

37. An apparatus, comprising:

means for receiving a bearer request message from a packet data network gateway, means for extracting session information from the bearer request message, the extracted session information including at least one of information regarding a calling party, a called party, and a communication type, and

means for storing or forwarding the extracted session information.

Description:
DESCRIPTION

DATA RETENTION FOR S8 HOME ROUTED ROAMING

Field of the invention

The present invention relates to apparatuses, methods, systems, computer programs, computer program products and computer-readable media regarding data retention for S8 home routed roaming.

Abbreviations

3GPP 3 rd Generation Partnership Project

AAR Authentication and Authorization Request (see IETF RFC 4005)

BBERF Bearer Binding and Event Reporting Function

BSS Base Station System

CSCF Call Session Control Function

GTP GPRS Tunneling Protocol

GPRS General Packet Radio Service

IBCF Interconnection Border Control Function

IMS Internet Protocol Multimedia Subsystem

IP Internet Protocol

HPLMN Home Public Land Mobile Network

HSS Home Subscriber Server

IMS IP Multimedia Subsystem

MME Mobility Management Entity

PCC Policy and Charging Control

PCRF Policy and Charging Rules Function

PLMN Public Land Mobile Network

PMIP Proxy Mobile IP

P-GW PDN Gateway

P-CSCF Proxy Call Session Control Function

RAR RE-Auth Request (see IETF RFC 3588)

S-CSCF Serving Call Session Control Function

SDP Session Description Protocol

SIP Session Initiation Protocol STR Session Termination Request (see IETF RFC 3588)

S-GW Serving Gateway

TAS Telecommunication Application Server

TrGW Trunking Gateway

URI Uniform Resource Identifier

VoLTE Voice over LTE

VPLMN Visited Public Land Mobile Network

Background of the invention

The Internet Protocol Multimedia Subsystem (IMS) is the standardized solution for Multimedia telephony over IP based networks, e.g. Voice over LTE (VoLTE) is utilizing IMS. It thus sees increased interest from the operator community. One requirement for VoLTE is to support roaming into visited PLMNs (Public Land Mobile Networks).

This invention is dealing with the so called S8/home routing based roaming model that has been selected by GSMA as one recommended roaming model for VoLTE. 3GPP SA2 is now studying technical impacts of S8HR in document [1 ].

More specific, this invention describes that the visited network can support so called data retention in case S8HR is used.

Fig. 1 is a diagram illustrating the reference architecture for S8/home routing based roaming model. In Fig. 1 , solid lines indicate the user plane and dashed lines indicate the signaling plane.

Regulatory requirements in the country of the VPLMN (Visited PLMN) can require that the VPLMN operator has to support so called data retention. For instance, data retention is required by regulations of the European Union. Data retention means that the VPLMN operator has to record data that is related to the traffic via his network nodes.

In case of VoLTE of a roaming UE this means that the S-GW will have to store data related to VoLTE calls, for instance the identities of the source of the communications (calling party) and the destination of the communication (called party), and the date, time and duration of the call. However, such data is part of the application layer protocol, and the S-GW has no understanding of any signalling above GTP-U, i.e. it has no understanding of Application Layer protocols, as can be seen from Fig. 2 showing the involved protocol stacks. The application layer protocol can even be encrypted, e.g. via IPsec.

In case of VoLTE, the data to be retained are encoded in SIP (Session Initiation Protocol) as application layer protocol. The data contains:

- Originating Identity

- Target Identity

- Time and duration of call

- Type of communication (e.g. voice call, video call, messaging session).

Technical details of S8HR is only about to be standardized, so the problem is not yet solved.

One alternative solution would be to provide deep inspection capabilities in the S-GW. In case of VoLTE this means that the S-GW would have to implement a SIP stack. From dynamics point of view, however, this is disadvantageous. Further it requires additional computing power.

References:

[1 ]: 3GPP TR 23.749

[2]: 3GPP TS 29.214

[3]: 3GPP TS 29.212

[4]: 3GPP TS 29.274

Summary of the Invention

It is therefore an object of the present invention to overcome the above mentioned problems and to provide apparatuses, methods, systems, computer programs, computer program products and computer-readable media regarding data retention for S8 home routed roaming.

According to an aspect of the present invention there is provided a method for use in a call session control function, comprising:

receiving a request for initiating a communication session, the request including at least information regarding a calling party, a called party, and information for deriving a communication type, extracting session information related to the communication session from the received request, the extracted session information including at least one of information regarding the calling party, the called party, the communication type and a time when the request is received, and

forwarding the session information to a policy and charging rules function.

According to another aspect of the present invention there is provided a method for use in a serving gateway, comprising:

receiving a bearer request message from a packet data network gateway, extracting session information from the bearer request message, the extracted session information including at least one of information regarding a calling party, a called party, and a communication type, and

storing or forwarding the extracted session information.

According to another aspect of the present invention there is provided an apparatus for use in a call session control function, comprising:

at least one processor,

and

at least one memory for storing instructions to be executed by the processor, wherein the at least one memory and the instructions are configured to, with the at least one processor, cause the apparatus at least to perform:

receiving a request for initiating a communication session, the request including at least information regarding a calling party, a called party, and information for deriving a communication type,

extracting session information related to the communication session from the received request, the extracted session information including at least one of information regarding the calling party, the called party, the communication type and a time when the request is received, and

forwarding the session information to a policy and charging rules function.

According to another aspect of the present invention there is provided an apparatus for use in a serving gateway, comprising

at least one processor,

and

at least one memory for storing instructions to be executed by the processor, wherein the at least one memory and the instructions are configured to, with the at least one processor, cause the apparatus at least to perform:

receiving a bearer request message from a packet data network gateway, extracting session information from the bearer request message, the extracted session information including at least one of information regarding a calling party, a called party, and a communication type, and

storing or forwarding the extracted session information.

According to another aspect of the present invention there is provided a computer program product comprising code means adapted to produce steps of any of the methods as described above when loaded into the memory of a computer.

According to a still further aspect of the invention there is provided a computer program product as defined above, wherein the computer program product comprises a computer- readable medium on which the software code portions are stored.

According to a still further aspect of the invention there is provided a computer program product as defined above, wherein the program is directly loadable into an internal memory of the processing device.

According to a still further aspect of the present invention there is provided an apparatus comprising:

means for receiving a request for initiating a communication session, the request including at least information regarding a calling party, a called party, and information for deriving a communication type,

means for extracting session information related to the communication session from the received request, the extracted session information including at least one of information regarding the calling party, the called party, the communication type and a time when the request is received, and

means for forwarding the session information to a policy and charging rules function.

According to a still further aspect of the present invention there is provided an apparatus comprising:

means for receiving a bearer request message from a packet data network gateway, means for extracting session information from the bearer request message, the extracted session information including at least one of information regarding a calling party, a called party, and a communication type, and

means for storing or forwarding the extracted session information.

Brief Description of the Drawings

These and other objects, features, details and advantages will become more fully apparent from the following detailed description of aspects/embodiments of the present invention which is to be taken in conjunction with the appended drawings, in which:

Fig. 1 is a diagram illustrating the reference architecture for S8/home routing based roaming model.

Fig. 2 is a diagram illustrating the involved protocol stacks.

Fig. 3 is a diagram illustrating an overview of architecture for illustration of the involved nodes according to certain aspects of the present invention.

Fig. 4 is a signaling diagram illustrating an example call flow for data retention according to certain aspects of the present invention.

Fig. 5 is a flowchart illustrating an example of a method according to certain aspects of the present invention.

Fig. 6 is a flowchart illustrating another example of a method according to certain aspects of the present invention.

Fig. 7 is a block diagram illustrating an example of an apparatus according to certain aspects of the present invention.

Detailed Description

In the following, certain aspects of the disclosure and embodiments of the present invention are described with reference to the drawings. For illustrating the present invention, the examples and embodiments will be described in connection with a cellular communication network based on a 3GPP based communication system, for example an LTE/LTE-A based system. However, it is to be noted that the present invention is not limited to an application using such types of communication systems or communication networks, but is also applicable in other types of communication systems or communication networks, like for example 2G and 3G communication networks or other wireless communication networks and the like.

The following examples versions and embodiments are to be understood only as illustrative examples. Although the specification may refer to "an", "one", or "some" example version(s) or embodiment(s) in several locations, this does not necessarily mean that each such reference is to the same example version(s) or embodiment(s), or that the feature only applies to a single example version or embodiment. Single features of different embodiments may also be combined to provide other embodiments. Furthermore, words "comprising" and "including" should be understood as not limiting the described embodiments to consist of only those features that have been mentioned and such example versions and embodiments may also contain also features, structures, units, modules etc. that have not been specifically mentioned.

The basic system architecture of a communication network where examples of embodiments of the invention are applicable may comprise a commonly known architecture of one or more communication systems comprising a wired or wireless access network subsystem and a core network. Such an architecture may comprise one or more communication network control elements, access network elements, radio access network elements, access service network gateways or base transceiver stations, such as a base station (BS), an access point or an eNB, which control a respective coverage area or cell and with which one or more communication elements or terminal devices such as a UE or another device having a similar function, such as a modem chipset, a chip, a module etc., which can also be part of a UE or attached as a separate element to a UE, or the like, are capable to communicate via one or more channels for transmitting several types of data. Furthermore, core network elements such as gateway network elements, policy and charging control network elements, mobility management entities, operation and maintenance elements, and the like may be comprised.

The general functions and interconnections of the described elements, which also depend on the actual network type, are known to those skilled in the art and described in corresponding specifications, so that a detailed description thereof is omitted herein. However, it is to be noted that several additional network elements and signaling links may be employed for a communication to or from a communication element or terminal device like a UE and a communication network control element like a radio network controller, besides those described in detail herein below.

The communication network is also able to communicate with other networks, such as a public switched telephone network or the Internet. The communication network may also be able to support the usage of cloud services. It should be appreciated that BSs and/or eNBs or their functionalities may be implemented by using any node, host, server or access node etc. entity suitable for such a usage.

Furthermore, the described network elements and communication devices, such as terminal devices or user devices like UEs, communication network control elements of a cell, like a BS or an eNB, access network elements like APs and the like, as well as corresponding functions as described herein may be implemented by software, e.g. by a computer program product for a computer, and/or by hardware. In any case, for executing their respective functions, correspondingly used devices, nodes or network elements may comprise several means, modules, units, components, etc. (not shown) which are required for control, processing and/or communication/signaling functionality. Such means, modules, units and components may comprise, for example, one or more processors or processor units including one or more processing portions for executing instructions and/or programs and/or for processing data, storage or memory units or means for storing instructions, programs and/or data, for serving as a work area of the processor or processing portion and the like (e.g. ROM, RAM, EEPROM, and the like), input or interface means for inputting data and instructions by software (e.g. floppy disc, CD-ROM, EEPROM, and the like), a user interface for providing monitor and manipulation possibilities to a user (e.g. a screen, a keyboard and the like), other interface or means for establishing links and/or connections under the control of the processor unit or portion (e.g. wired and wireless interface means, radio interface means comprising e.g. an antenna unit or the like, means for forming a radio communication part etc.) and the like, wherein respective means forming an interface, such as a radio communication part, can be also located on a remote site (e.g. a radio head or a radio station etc.). It is to be noted that in the present specification processing portions should not be only considered to represent physical portions of one or more processors, but may also be considered as a logical division of the referred processing tasks performed by one or more processors. Certain aspects of the present invention relate to the so called S8/home routing based roaming model as one recommended roaming model for VoLTE. In particular, certain aspects of the present invention describe that the visited network can support so called data retention in case S8HR is used.

Fig. 3 is a diagram illustrating an overview of architecture for illustration of the involved nodes according to certain aspects of the present invention.

One the right side of Fig. 3, there is shown the Home PLMN of party A (HPLMN A) 31 including the P-CSCF 31 1 and the PCRF 312 which are connected to each other via the Rx- interface. The PCRF 312 is further connected to the P-GW 313 via the Gx-interface and the P-GW 313 is also connected to the P-CSCF 31 1 .

On the left side of Fig. 3, there is shown the Visited PLMN of party A (VPLMN A) 32 including the S-GW 321 which is connected to the P-GW of the HPLMN A 31 via the S8- interface. The S-GW 321 is further connected to the MME 322 via the S1 1 interface and is also connected to E-UTRAN 323 via the S1 -U interface. The E-UTRAN 323 is also connected to the MME 322 and to a user equipment (UE) 324.

According to certain aspects of the present invention, it is proposed that the P-CSCF 31 1 in the home network HPLMN A 31 extracts data to be retained from SIP signaling related to the call establishment (e.g. Called and calling party identities, and time and type of communication).

Then, the P-CSCF 31 1 provides these data to the PCRF312 via the Rx interface (as defined in document [2]), for instance within a new transparent container, as part of the service information related to the call being established.

Further, the PCRF 312 forwards these data to the P-GW 313 via the Gx interface, or alternatively, to a BBERF (Bearer Binding and Event Reporting Function) via the Gxx interface (as defined in document [3]) (not illustrated in Fig. 3), for instance within the same transparent container, as part of the policy and charging information related to the call being established. (Both PCRF 312 and P-GW 313 or BBERF are home network nodes.)

The P-GW 313 forwards the data, for instance within the same transparent container, in GTP (as defined in document [4]) via the S8 interface to the S-GW 321 in the VPLMN A 32 as part of the signaling to establish a bearer for the call being established. Alternatively, the BBERF (not shown) forwards the data, for instance within the same transparent container, via PMIP (Proxy Mobile IP) to the S-GW 321.

Finally, the S-GW 321 stores this data, i.e. provides data retention capabilities. The S-GW 321 can also add further data related to the radio bearer, for instance the location of mobile communication equipment, to the data to be retained.

In order to derive the duration of the call, which also needs to be retained by the S-GW, two alternatives are possible.

According to the first alternative, the S-GW records when the bearer, for which it obtained retention data within GTP during its establishment, is terminated, and calculates the duration between the establishment and the termination of the bearer.

According to the second alternative, the P-CSCF derives the duration of the call and/or the time of the call termination from SIP signaling at call termination. The P-CSCF forwards this information to the PCRF as part of the update of the session information at call termination, for instance again within a transparent container. The PCRF forwards this information to the P-GW as part of the update of the policy and charging control information at IP CAN session termination. The P-GW forwards this information to the S-GW via GTP signaling to update or terminate the bearer for the call. The S-GW stores this information as part of the retained data.

Fig. 4 is a signaling diagram illustrating an example call flow for data retention according to certain aspects of the present invention. The signaling elements and procedures according to certain aspects of the present invention are marked with italic font.

In step S41 , the P-CSCF 31 1 receives a SIP INVITE request. (For a mobile originated call, the INVITE is received from the served UE. For a mobile terminated call, the INVITE is received from the remote peer, which are both not illustrated in Fig. 4.) Within the INVITE request for a mobile originated call, the called party identity is designated via the request URI, and the SDP (Session Description Protocol) offer contains information about the desired media that can be used to derive the type of the communication. For a mobile originating call, the P-CSCF has knowledge about the identity of the served UE acting as caller and inserts the P-Asserted-ldentity header, which then contains the calling party identity. Within the INVITE request for a terminating call, the calling party identity is designated in the P- Asserted Identity header field, and the called party identity is designated in the P-Called- Party-ID header field.

In step S42, the P-CSCF 31 1 extracts at least one of information about the media for the service information, information about the calling and called parties and the type of the communication (e.g. voice call) and records the time.

Then, the P-CSCF 31 1 forwards the SIP INVITE request to the called party in step S43 and receives a SIP message containing the SDP answer in step S44.

In step S45, the P-CSCF 31 1 extracts further service information from the SDP answer received in step S44.

Then, the P-CSCF 31 1 sends a Diameter AA-Request containing the extracted service information to the PCRF 312 in step S46. According to certain aspects of the present invention, the P-CSCF 311 also adds the calling and called party identities, the type of the communication and possibly the recorded time. According to some example versions of the present invention, the P-CSCF 31 1 uses a transparent container to encapsulate this added information.

In step S47, the P-CSCF forwards the SIP message containing the SDP answer.

Upon reception of message in step S46, the PCRF 312 derives PCC rules from the service information and sends them in a Diameter RA-Request to the P-GW 313 in step S48. According to certain aspects of the present invention, the PCRF 312 also adds the received calling and called party identities, the type of the communication and the possibly recorded time to the RAR. If this information is embedded in a transparent container, the PCRF 312 adds the transparent container to the RAR. The added information or transparent container is added to a PCC rule derived from the service information to achieve that the P-GW 313 will add this information to the bearer corresponding to the PCC rule in step S49.

Thus, the P-GW 313 inspects the PCC rule and decides that a dedicated bearer is required for the media. It sends a GTP "Create Bearer Request" message in step S49 to set up the bearer. The P-GW 313 may also find that a suitable bearer towards the served UE already exists, but will then need to modify the bearer to provide information towards the served UE where to send media and will then send a GTP "Modify Bearer Request" message (not illustrated in Fig. 4). According to certain aspects of the present invention, the P-GW 313 also adds the received calling and called party identities, the type of the communication and the possibly recorded time to the GTP message. If this information is embedded in a transparent container, the P-GW 313 adds the transparent container to the GTP message.

The S-GW 321 receives the GTP message sent in step S49. According to certain aspects of the present invention, in step S410 the S-GW 321 extracts the contained calling and called party identities, the type of the communication and the possibly recorded time. If no time is contained, the S-GW 321 records the time when it receives the GTP message. The S-GW 321 stores this information and possibly adds additional information about the location (e.g. cell ID) and the type and/or identity of the mobile equipment that the S-GW 321 can obtain from other nodes in the radio access network. The S-GW 321 can also forward this stored information to other network nodes for a centralized storage.

When the call is being terminated, the P-CSCF 31 1 will receive a SIP "BYE" message from the calling party in step S41 1 .

In step S412, the P-CSCF 31 1 can record the time and calculate the duration of the call using the previously stored time when the INVITE message was received. Then, the P-CSCF 311 forwards the SIP BYE message to the called party in step S413.

The P-CSCF 31 1 further sends a Diameter ST-Request to the PCRF 312 in step S414. According to certain aspects of the present invention, the P-CSCF 31 1 can add the possibly recorded time or the calculated duration. According to some example versions of the present invention, the P-CSCF 31 1 uses a transparent container to encapsulate this added information.

Upon reception of message sent in step S414, the PCRF 312 derives PCC rule(s) to be removed from the service information and sends a request to remove those PCC rule(s) in a Diameter RA-Request to the P-GW 313 in step S415. According to certain aspects of the present invention, the PCRF 312 also adds the possibly received time or duration to the RAR. If this information is embedded in a transparent container, the PCRF 312 adds the transparent container to the RAR. The added information or transparent container is added to the request to delete a PCC rule derived from the service information to achieve that the P-GW 313 will add this information to the bearer corresponding to the PCC rule in step S416. The P-GW 313 inspects the PCC rule(s) to be removed and decides that the dedicated bearer for the media needs to be terminated. It sends a GTP "Delete Bearer Request" message in step S416 to terminate that bearer. The P-GW 313 may also decide to retain that bearer towards the served UE for other media, but will then need to modify the bearer to provide information towards the served UE where to send media and will then send a GTP "Modify Bearer Request" message (not illustrated in Fig. 4). According to certain aspects of the present invention, the P-GW 313 also adds the possibly received time or duration to the GTP message. If this information is embedded in a transparent container, the P-GW 313 adds the transparent container to the GTP message.

The S-GW 321 receives the GTP message sent in step S416. According to certain aspects of the present invention, the S-GW 321 extracts the possibly received time or duration. If a time is contained, the S-GW 321 calculates the duration of the call by comparing the time with the time stored in step S410. If no time or duration is contained, the S-GW 321 records the time when it received the GTP message and calculates the duration of the call by comparing the time with the time stored in step S410. The S-GW 321 stores this information. The S-GW 321 can also forward this stored information to other network nodes for a centralized storage.

In summary, as set out above, due to regulatory requirements, the VPLMN needs to retain the calling and called party identities for voice calls. This information is only available in IMS nodes in the HPLMN. Thus, according to certain aspects of the present invention as set out above, the P-CSCF in the HPLMN sends this information via PCC interfaces to the P-GW, which forwards it to the S-GW in the VPLMN that stores the data for retention purposes.

It is an advantage according to certain aspects of the present invention that existing signaling messages at the Rx, Gx and S8 interfaces can be used to transport the new information. This avoids an increase in the signaling load and reduces implementation efforts. Implementation impacts at the PCRF and P-GW can be further reduced via a transparent data container that merely needs to be forwarded.

In the following, a more general description of some example version of embodiments of the present invention is made with respect to Figs. 5 to 7. Fig. 5 is a flowchart illustrating an example of a method according to example versions of the present invention.

According to example versions of the present invention, the method may be implemented in or may be part of a proxy call session control function or the like. The method comprises receiving a request for initiating a communication session in a step S51 . The request includes at least information regarding a calling party, a called party, and information for deriving a communication type. Further, the method comprises extracting session information related to the communication session from the received request in a step S52, the extracted session information including at least one of information regarding the calling party, the called party, the communication type and a time when the request is received. Furthermore, the method comprises forwarding the session information to a policy and charging rules function in a step S53.

According to some example versions of the present invention, the session information is forwarded to the policy and charging rules function in an authentication request message.

According to some example versions of the present invention, the method further comprises extracting service information from the request and from a session initiation answer message received by the call session control function, and forwarding the service information to the policy and charging rules function in an authentication request message.

According to some example versions of the present invention, the session information and the service information is encapsulated in a transparent container, the transparent container being added to an authentication request message forwarded to the policy and charging rules function.

According to some example versions of the present invention, the method further comprises receiving a request for terminating the communication session, and recording a time when the request for terminating the communication session is received.

According to some example versions of the present invention, the method further comprises calculating a duration of the communication session based on the time when the request for initiating the communication session is received and the time when the request for terminating the communication session is received. According to some example versions of the present invention, the method further comprises forwarding the time when the request for terminating the communication session is received or the calculated duration to the policy and charging rules function.

According to some example versions of the present invention, the time or the duration is forwarded to the policy and charging rules function in a session termination request.

According to some example versions of the present invention, the time or the duration is encapsulated in a transparent container, the transparent container being added to the session termination request forwarded to the policy and charging rules function.

Fig. 6 is a flowchart illustrating another example of a method according to example versions of the present invention.

According to example versions of the present invention, the method may be implemented in or may be part of a serving gateway or the like. The method comprises receiving a bearer request message from a packet data network gateway in a step S61 , and extracting session information from the bearer request message in a step S62, the extracted session information including at least one of information regarding a calling party, a called party, and a communication type. Further, the method comprises storing or forwarding the extracted session information in a step S63.

According to some example versions of the present invention, the extracted session information may be stored in the serving gateway and/or may be forwarded for storage to an external entity.

According to some example versions of the present invention, the method further comprises recording a first time based on a time when the bearer request message is received or a time indicated in the session information extracted from the bearer request message indicating when a request for initiating a communication session has been received by a call session control function.

According to some example versions of the present invention, the method further comprises receiving a bearer delete message from the packet data network gateway. According to some example versions of the present invention, the method further comprises extracting a second time included in the bearer delete message indicating when a request for terminating a communication session has been received by the call session control function, and calculating a duration of the communication session based on the first time and the second time extracted from the bearer delete message, and storing or forwarding the calculated duration.

According to some example versions of the present invention, the method further comprises recording a second time when the bearer delete message is received, and calculating a duration of the communication session based on the first time and the second time recorded when the bearer delete message is received, and storing or forwarding the calculated duration.

According to some example versions of the present invention, the method further comprises extracting a duration of a communication session from the bearer delete message, and storing or forwarding the extracted duration.

According to some example versions of the present invention, the bearer request message is a request for creating a new bearer or a request for modifying an existing bearer.

Fig. 7 is a block diagram illustrating an example of an apparatus according to some example versions of the present invention.

In Fig. 7, a block circuit diagram illustrating a configuration of an apparatus 70 is shown, which is configured to implement the above described aspects of the invention. It is to be noted that the apparatus 70 shown in Fig. 7 may comprise several further elements or functions besides those described herein below, which are omitted herein for the sake of simplicity as they are not essential for understanding the invention. Furthermore, the apparatus may be also another device having a similar function, such as a chipset, a chip, a module etc., which can also be part of an apparatus or attached as a separate element to the apparatus, or the like.

The apparatus 70 may comprise a processing function or processor 71 , such as a CPU or the like, which executes instructions given by programs or the like. The processor 71 may comprise one or more processing portions dedicated to specific processing as described below, or the processing may be run in a single processor. Portions for executing such specific processing may be also provided as discrete elements or within one or further processors or processing portions, such as in one physical processor like a CPU or in several physical entities, for example. Reference sign 72 denotes transceiver or input/output (I/O) units (interfaces) connected to the processor 71 . The I/O units 72 may be used for communicating with one or more other network elements, entities, terminals or the like. The I/O units 72 may be a combined unit comprising communication equipment towards several network elements, or may comprise a distributed structure with a plurality of different interfaces for different network elements. The apparatus 70 further comprises at least one memory 73 usable, for example, for storing data and programs to be executed by the processor 71 and/or as a working storage of the processor 71.

The processor 71 is configured to execute processing related to the above described aspects.

In particular, the apparatus 70 may be implemented in or may be part of a proxy call session control function or the like, and may be configured to perform a method as described in connection with Fig. 5. Thus, the processor 71 is configured to perform receiving a request for initiating a communication session, the request including at least information regarding a calling party, a called party, and information for deriving a communication type, extracting session information related to the communication session from the received request, the extracted session information including at least one of information regarding the calling party, the called party, the communication type and a time when the request is received, and forwarding the session information to a policy and charging rules function.

According to some example versions of the present invention, the apparatus 70 may be implemented in or may be part of a serving gateway or the like, and may be configured to perform a method as described in connection with Fig. 6. Thus, the processor 71 is configured to perform receiving a bearer request message from a packet data network gateway, extracting session information from the bearer request message, the extracted session information including at least one of information regarding a calling party, a called party, and a communication type, and storing or forwarding the extracted session information.

For further details regarding the functions of the apparatus 70, reference is made to the description of the methods according to some example versions of the present invention as described in connection with Figs. 5 and 6. Thus, it is noted that the apparatus for use in a proxy call session control function, and the apparatus for use in a serving gateway, generally have the same structural components, wherein these components are configured to execute the respective functions of the network elements, i.e. the proxy call session control function and the serving gateway, respectively, as set out above.

In the foregoing exemplary description of the apparatus, only the units/means that are relevant for understanding the principles of the invention have been described using functional blocks. The apparatus may comprise further units/means that are necessary for its respective operation, respectively. However, a description of these units/means is omitted in this specification. The arrangement of the functional blocks of the apparatus is not construed to limit the invention, and the functions may be performed by one block or further split into sub-blocks.

When in the foregoing description it is stated that the apparatus (or some other means) is configured to perform some function, this is to be construed to be equivalent to a description stating that a (i.e. at least one) processor or corresponding circuitry, potentially in cooperation with computer program code stored in the memory of the respective apparatus, is configured to cause the apparatus to perform at least the thus mentioned function. Also, such function is to be construed to be equivalently implementable by specifically configured circuitry or means for performing the respective function (i.e. the expression "unit configured to" is construed to be equivalent to an expression such as "means for").

For the purpose of the present invention as described herein above, it should be noted that

- method steps likely to be implemented as software code portions and being run using a processor at an apparatus (as examples of devices, apparatuses and/or modules thereof, or as examples of entities including apparatuses and/or modules therefore), are software code independent and can be specified using any known or future developed programming language as long as the functionality defined by the method steps is preserved;

- generally, any method step is suitable to be implemented as software or by hardware without changing the idea of the aspects/embodiments and its modification in terms of the functionality implemented;

- method steps and/or devices, units or means likely to be implemented as hardware components at the above-defined apparatuses, or any module(s) thereof, (e.g., devices carrying out the functions of the apparatuses according to the aspects/embodiments as described above) are hardware independent and can be implemented using any known or future developed hardware technology or any hybrids of these, such as MOS (Metal Oxide Semiconductor), CMOS (Complementary MOS), BiMOS (Bipolar MOS), BiCMOS (Bipolar CMOS), ECL (Emitter Coupled Logic), TTL (Transistor-Transistor Logic), etc., using for example ASIC (Application Specific IC (Integrated Circuit)) components, FPGA (Field- programmable Gate Arrays) components, CPLD (Complex Programmable Logic Device) components or DSP (Digital Signal Processor) components;

- devices, units or means (e.g. the above-defined apparatuses, or any one of their respective units/means) can be implemented as individual devices, units or means, but this does not exclude that they are implemented in a distributed fashion throughout the system, as long as the functionality of the device, unit or means is preserved;

- an apparatus may be represented by a semiconductor chip, a chipset, or a (hardware) module comprising such chip or chipset; this, however, does not exclude the possibility that a functionality of an apparatus or module, instead of being hardware implemented, be implemented as software in a (software) module such as a computer program or a computer program product comprising executable software code portions for execution/being run on a processor;

- a device may be regarded as an apparatus or as an assembly of more than one apparatus, whether functionally in cooperation with each other or functionally independently of each other but in a same device housing, for example.

In general, it is to be noted that respective functional blocks or elements according to above- described aspects can be implemented by any known means, either in hardware and/or software, respectively, if it is only adapted to perform the described functions of the respective parts. The mentioned method steps can be realized in individual functional blocks or by individual devices, or one or more of the method steps can be realized in a single functional block or by a single device.

Generally, any method step is suitable to be implemented as software or by hardware without changing the idea of the present invention. Devices and means can be implemented as individual devices, but this does not exclude that they are implemented in a distributed fashion throughout the system, as long as the functionality of the device is preserved. Such and similar principles are to be considered as known to a skilled person.

Software in the sense of the present description comprises software code as such comprising code means or portions or a computer program or a computer program product for performing the respective functions, as well as software (or a computer program or a computer program product) embodied on a tangible medium such as a computer-readable (storage) medium having stored thereon a respective data structure or code means/portions or embodied in a signal or in a chip, potentially during processing thereof.

It is noted that the aspects/embodiments and general and specific examples described above are provided for illustrative purposes only and are in no way intended that the present invention is restricted thereto. Rather, it is the intention that all variations and modifications which fall within the scope of the appended claims are covered.