8 Scenarios relating to a level of service of application level

24.5233GPPArchitecture and functional descriptionCore and enterprise Next Generation Network (NGN) interaction scenariosRelease 17TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

8.1 General

For each of the scenarios presented in this clause, it is possible for the NGN to provide services either at the session establishment and control level or at the application level, as described in subclause 4.2. Some of the functional entity diagrams show the involvement of an AS. Where an AS is shown, this does not necessarily constitute provision of services at the application level, as described in subclause 4.1. It is possible to deploy an AS for realizing services at the session establishment and control level.

NOTE: Corporate networks can be connected in different arrangements. One is connecting them over an interface to a P-CSCF (subscription-based arrangement), the other is when it is connected over an interface to an IBCF (peering-based arrangement).

8.2 Scenario 4: Hosted Enterprise Services (HES)

8.2.1 Introduction

This scenario describes the provision of capabilities of the NGN to support end users directly attached to the NGN with services belonging to the enterprise network. Support of both the private network routeing capabilities and services delivered to the end enterprise user are provided within the AS supporting the HES application. In addition to the existing IMS capabilities, the HSS supports service profiles for SIP URIs with a URI parameter of user=phone and representing a PNP number.

8.2.2 Involved functional entities – originating

Figure 8.2.1: HES scenario originating functional entities (use of NASS and RACS)

Figure 8.2.1A: HES scenario originating functional entities (use of PCC)

NOTE 1: Figure 8.2.1 and figure 8.2.1A do not show the intermediate functions between the P-CSCF and the S-CSCF, or those between the S-CSCF and the terminating side.

NOTE 2: In addition to the scenarios shown in figure 8.2.1 and figure 8.2.1A, the HES application can be supported by an enterprise connected using an ISC gateway function.

See 3GPP TS 24.524 [4] for further information.

8.2.3 Involved functional entities – terminating

Figure 8.2.2: HES scenario terminating functional entities (use of NASS and RACS)

Figure 8.2.2A: HES scenario terminating functional entities (use of PCC)

NOTE 1: Figure 8.2.2 and figure 8.2.2A does not show the intermediate functions between the P-CSCF and the S-CSCF, or any intermediate functions before the S-CSCF from the originating side.

NOTE 2: In addition to the scenarios shown in figure 8.2.2 and figure 8.2.2A, the HES application can be supported by an enterprise connected using an ISC gateway function.

See 3GPP TS 24.524 [4] for further information.

8.2.4 Interoperability with other scenarios

The originating side HES scenario can interoperate with any other terminating scenario. A break-out function needs to be deployed when traffic leaves the enterprise environment and becomes public network traffic. This break-out function can form part of the HES application.

The terminating side HES scenario can interoperate with any other originating scenario. A break-in function needs to be deployed when public network traffic enters the enterprise environment. This break-in function can form part of the HES application.

8.2.5 Emergency calls

For a UE supported in the HES environment, citizen to authority calls are normally treated as if the UE was supported by the NGN in the normal public subscriber manner, see 3GPP TS 23.167 [1]. 3GPP TS 24.524 [4] for further information.

NOTE: Some enterprises may require alternative arrangements, whereby emergency calls are routed to a private PSAP.

8.2.6 Configuration / provisioning issues

HES users are configured in the HSS in the same manner as subscribers for the public NGN capabilities. The service profile and filter criteria relate to the provision of specialized HES by an application server. See 3GPP TS 24.524 [4] for further information. In addition to the existing IMS capabilities, the UPSF supports service profiles for SIP URIs with a URI parameter of user=phone and representing a PNP number.

The IMS routeing functions (e.g. BGCF, S-CSCF, I-CSCF) will require appropriate provisioning to route private network traffic, unless all calls originated from or terminated to the HES are public network traffic.

8.2.7 Security issues

3GPP TS 24.524 [4] shall apply to the interconnection between the NGCN UE and the NGN.

NOTE: The present document references 3GPP TS 33.203 [7].

8.2.8 Charging issues

Inter Operator Identifiers (IOI) specific to the NGCN shall be exchanged between the S-CSCF supporting the hosted enterprise users and the entities supporting the remote side. See 3GPP TS 24.524 [4] for further information.

NOTE: IOI usage is not fully defined for enterprise communication in this release.

8.2.9 Transport control issues

The NASS, RACS and transport processing functions are used in an identical fashion to a CND and CNG receiving NGN services. See 3GPP TS 24.524 [4] for further information.

8.3 Scenario 5: Business trunking (subscription based)

8.3.1 Introduction

This scenario describes the provision of capabilities of the NGN to support end users attached to an NGCN. In this case each site of the NGCN has a service subscription to the IMS, the private extensions behind the NGCN do not need their own service subscription, since they are owned and managed by the NGCN. The NGCN site interfaces to the NGN using SIP as the control protocol.

An AS is used to provide business trunking applications, e.g. those defined in 3GPP TS 22.519 [2], subclause 4.4. If such capabilities are not required, then the AS is not included in any request processing.

8.3.2 Involved functional entities – originating

Figure 8.3.1 shows the functional entities involved in the originating scenario in support subscription based business trunking.

Figure 8.3.1: Business trunking scenario originating functional entities

NOTE 1: Figure 8.3.1 does not show the intermediate functions between the P-CSCF and the S-CSCF, or those between the S-CSCF and the terminating side.

NOTE 2: In addition to the scenarios shown in figure 8.3.1, the business trunking application can be supported by an enterprise connected using an ISC gateway function.

See 3GPP TS 24.525 [5] for further information.

8.3.3 Involved functional entities – terminating

Figure 8.3.2 shows the functional entities involved in the terminating scenario in support subscription based business trunking.

Figure 8.3.2: Business trunking scenario terminating functional entities

NOTE 1: Figure 8.3.2 does not show the intermediate functions between the P-CSCF and the S-CSCF, or any intermediate functions before the S-CSCF from the originating side.

NOTE 2: In addition to the scenarios shown in figure 8.3.1, the business trunking application can be supported by an enterprise connected using an ISC gateway function.

See 3GPP TS 24.525 [5] for further information.

8.3.4 Interoperability with other scenarios

The originating side business trunking scenario can interoperate with any other terminating scenario. A break-out function needs to be deployed when traffic leaves the enterprise environment and becomes public network traffic.

The terminating side business trunking scenario can interoperate with any other originating scenario. A break-in function needs to be deployed when public network traffic enters the enterprise environment.

8.3.5 Emergency calls

For an NGCN site that has a subscription to the IMS, emergency calls ingressing to the NGN are normally treated as if the NGCN was supported by the NGN in the normal public subscriber manner, see 3GPP TS 23.167 [1]. See 3GPP TS 24.525 [5] for further information.

NOTE: Some enterprises may require alternative arrangements, whereby emergency calls are routed to a private PSAP.

8.3.6 Configuration / provisioning issues

NGCN sites are configured in the HSS in the same manner as subscribers for the public NGN capabilities. The service profile and filter criteria relate to the provision of specialized enterprise services by the business trunking application; it is these services that are supported on an AS. See 3GPP TS 24.525 [5] for further information.

8.3.7 Security issues

3GPP TS 24.525 [5] shall apply to the interconnection between the NGCN UE and the NGN.

NOTE: The present document references 3GPP TS 33.203 [7] which contains the required provisions.

8.3.8 Charging issues

Inter Operator Identifiers (IOI) specific to the enterprise subscription for the NGCN shall be exchanged between the
S-CSCF serving the NGCN site and the entities supporting the remote side. See 3GPP TS 24.525 [5] for further information.

NOTE: IOI usage is not fully defined for enterprise communication in this release.

8.3.9 Transport control issues

The NGCN site interfaces to the NGN using the CNG which can be an integral part of the NGCN equipment.

The media requirements identified by the control protocol use the transport processing functions, and may be supported by functionality in the NASS and RACS.

Static IP address assignment is valid and does not need NASS. MACF provides DHCP server dynamic address which is part of NASS. UAF is for authentication.

8.4 Scenario 6: Business trunking (peering based)

8.4.1 Introduction

This scenario describes the provision of capabilities of the NGN to support end users attached to an NGCN. In this case the NGCN operator has a service level agreement with the IMS operator. Services are provided to the private extensions behind the NGCN using the NGCN. The NGCN sites interface to the NGN using SIP as the control protocol.

Intelligent routeing tables at the routeing function are used to provided business trunking applications, e.g. those defined in 3GPP TS 22.519 [2], subclause 4.4. One mechanism to support such functionality is to use an AS attached to a transit function (see 3GPP TS 23.218 [11]) using the ISC interface. If such capabilities are not required, then the AS is not included in any request processing.

8.4.2 Involved functional entities – originating

Figure 8.4.1 shows the functional entities involved in the originating scenario in support of peering-based business trunking.

NOTE: One or more routeing functional entities can appear in the originating side for this scenario.

Figure 8.4.1: Business trunking scenario originating functional entities

NOTE: For the functionality of the intelligent routeing tables see subclause 6.2.6 of 3GPP TS 24.525 [5]). One mechanism to support such functionality is to use an AS attached to a transit function (see 3GPP TS 23.218 [11]) using the ISC interface.

See 3GPP TS 24.525 [5] for further information.

8.4.3 Involved functional entities – terminating

Figure 8.4.2 shows the functional entities involved in the terminating scenario in support of peering-based business trunking.

NOTE: One or more routeing functional entities can appear in the originating side for this scenario.

Figure 8.4.2: Business trunking scenario terminating functional entities

See 3GPP TS 24.525 [5] for further information.

8.4.4 Interoperability with other scenarios

NOTE: The functionality provided by the routeing function is that of a SIP proxy, and the functionality provided by the IBCF is that of a session border controller, so interoperability can be provided with existing solutions not based on IMS. In this case, the procedures of 3GPP TS 29.162 [6] will apply at the interworking point. The possible functionalities of a session border controller are described in IETF RFC 5863 [9]. Such interworking may be limited by the SIP extensions that are supported across the interface. ETSI ES 282 001 [3] provides for an IWF which may also provide some appropriate functionality in this respect.

8.4.5 Emergency calls

None of the functional entities in this scenario have any functionality specific to the recognition of emergency calls or to the substitution of the Request-URI when such a call exists. Identification of emergency calls is therefore expected to be performed in the NGCN. However, the routeing tables are expected to be configured to route private network traffic in a manner different to public network traffic. Delivering emergency calls is integral to that routeing configuration.

NOTE: Some enterprises may require alternative arrangements, whereby emergency calls are routed to a private PSAP.

8.4.6 Configuration / provisioning issues

NGCN sites are configured in the same manner as service level agreements with other public network operators. See 3GPP TS 24.525 [5] for further information.

The IMS routeing functions will require appropriate provisioning to route private network traffic, and to provide the business trunking applications, unless all calls originated from or terminated to the business trunking are public network traffic.

8.4.7 Security issues

3GPP TS 24.525 [5] shall apply to the interconnection between the NGCN UE and the NGN.

NOTE: The present document references 3GPP TS 33.210 [10].

8.4.8 Charging issues

Inter Operator Identifiers (IOI) shall be exchanged between the NGCN and the NGN.

NOTE: IOI usage is not fully defined for enterprise communication in this release.

8.4.9 Transport control issues

NOTE: Definition of the transport control issues in this scenario is outside the scope of this release of the present document.