Patent Description:
Computer systems in a communications network may comprise one or more nodes, which may also be referred to simply as nodes. A node may comprise one or more processors which, together with computer program code may perform different functions and actions, a memory, a receiving and a sending port. A node may be, for example, a server.

The standardization organization 3GPP is currently in the process of specifying a New Radio Interface called New Radio (NR) or <NUM>-Universal Terrestrial Radio Access (UTRA), as well as a Fifth Generation (<NUM>) Packet Core Network, which may be referred to as Next Generation (NG) Core Network, abbreviated as NG-CN, NGC or <NUM> CN.

Currently, in the <NUM> architecture, the concept of network slicing has been introduced, which may be understood as "a set of network functions, and resources to run these network functions, forming a complete instantiated logical network to meet certain network characteristics required by the Service Instance(s). " An instantiated logical network may be understood as a dedicated set of instantiated network resources, software and hardware, that may be understood to form a complete network configuration isolated from other logical network instances, for a set of user terminals authorized to be connected to the logical network instance, that is, a network slice instance.

Network slicing may be understood to primarily comprise the following components: physical resource, logical resource, and network function.

Physical resource may be understood as a physical asset capable of performing computation, storage or transport including radio access. Logical resource may be understood as a partition of a physical resource, or grouping of multiple physical resources dedicated to a Network Function or shared between a set of Network Functions. A Network Function (NF) may be understood to refer to processing functions executing a dedicated task in a network. This may include, but is not limited to, telecommunication nodes functionality, as well as switching functions, e.g., Ethernet switching functions, and Internet Protocol (IP) routing functions.

A Network slice may be defined within a Public Land Mobile Network (PLMN) and may be understood to include a Core Network Control Plane and User Plane Network Functions, and, in the serving PLMN, at least one of the following: the NG Radio Access Network and the N3IWF functions to the non-3GPP Access Network.

In the home network, the PLMN Operator may manage and orchestrate the Network Slicing operations for the <NUM> subscribers. These slicing operations may include: design, instantiate, operate and decommission Network Slices for the <NUM> subscribers. The slice selection mechanism may be based on PLMN, Access Point Name (APN), UE Usage type, Single Network Slice Selection Assistance Information (S-NSSAI) etc..

The IP Multimedia Subsystem (IMS) may be understood as an architectural framework for delivering IP multimedia services, that is, IMS services, such as Voice over LTE (VoLTE) and Rich Communication Services (RCS) over a telecommunications network. VoLTE may be understood as a service that supports calls over a <NUM> LTE network, rather than over <NUM> or <NUM> connections which may be usually used. RCS may be understood as a communication protocol between mobile telephone carriers and between phone and carrier, which may provide SMS-type messages with a text-message system that may be understood to be richer, provides phonebook polling, and may transmit in-call multimedia.

Discussions are currently ongoing in 3GPP, see for example, TR <NUM> V1. <NUM>, on the impacts on the IMS domain in relation to 5GC network slicing, e.g., in the case where the IMS domain may offer different services to different 5GC network slices, see 3GPP <NUM> Annex AA. <NUM> Architectural Support.

IMS Voice over LTE (VoLTE) and Rich Communication Services (RCS) services as of Global System for Mobile Communications Association (GSMA) NG. <NUM> are to a large extent supported among mobile network operators (MNO).

Some operators may want their own dual IMS networks to perform different IMS services, e.g., in the case of VoLTE and RCS as IMS services, one for VoLTE, one for RCS. Reasons for separating the networks are many, for example to keep track of Operating Expenses (OPEX) benefits, ability to upgrade, modify, re-configure and regression test, an IMS network function belonging to one IMS slice without risking traffic disturbance in the other.

Hence one and the same subscriber and device, e.g., a smartphone, may be served by dual IMS networks and/or slices.

Currently, however, a technology and/or mechanism does not exist for dispatching terminating IMS service sessions, e.g., VoLTE and RCS, to the right IMS slice, that is, the one of the dual IMS slices that may be handling the service.

<CIT> discloses a method performed by a wireless device relating to registering with an IMS network slice or initiating a session using an IMS network slice, comprising sending a message to an IMS node via a radio access network, the message comprising an identifier of a desired IMS network slice. In this manner, IMS network slicing is enabled. <CIT> discloses an IMS slice selection manager implemented at an edge of the IMS network slices. The IMS slice selection manager receives an IMS slice selection policy, and receives an IMS service request for an IMS service. The IMS slice selection manager selects an IMS network slice to provide the IMS service based on the IMS slice selection policy, and causes routing of the IMS service request to the selected IMS network slice.

Further details are defined in the dependent claims.

It is an object of embodiments herein to provide a method for handling provision of an Internet IMS service in a communications network.

According to a first aspect of embodiments herein, the object is achieved by a method, performed by a first node. The first node operates in a communications network. The method is for handling provision of an Internet Protocol Multimedia Subsystem (IMS) service in the communications network. The communications network comprises a first slice handling a first IMS service, and a second slice handling a second IMS service. The first node obtains , from a second node operating in the communications network at least one of: a first indication and a second indication. The first indication is of a first routing service instance for a third node comprised in the first slice. The third node handles the first IMS service. The second indication is of a second routing service instance for a fourth node comprised in the second slice. The fourth node handles the second IMS service. The first node also routes a request, received from a fifth node operating in another communications network, to one of the third node and the fourth node. One of the following applies. With the proviso that the received request is for the first IMS service, the routing is based on the obtained first indication. With the proviso that the received request is for the second IMS service, the routing is based on the obtained second indication.

According to a second aspect of embodiments herein, the object is achieved by a method, performed by the second node. The second node operates in the second communications network. The method is for handling provision of an IMS service in the communications network. The communications network comprises the first slice handling the first IMS service, and the second slice handling the second IMS service. The second node provides, to the first node operating in the communications network, at least one of: the first indication and the second indication. The first indication of the first routing service instance for the third node comprised in the first slice. The third node handles the first IMS service. The first indication enables routing of the first request for the first IMS service to the third node. The second indication for the second routing service instance for the fourth node comprised in the second slice. The fourth node handles the second IMS service. The second indication enables routing of the second request for the second IMS service to the fourth node.

According to a third aspect of embodiments herein, the object is achieved by a method, performed by the seventh node. The seventh node operates in the first communications network. The method is for handling provision of an IMS service in the communications network. The seventh node manages a terminating_ IMS Call Session Control Function (ICSCF). The communications network comprises a slice handling an IMS service. The seventh node registers with the second node as a provider of an IMS service. The second node manages a Network Repository Function (NRF) in the communications network. The seventh node also provides the IMS service based on the registration.

According to a fourth aspect of embodiments herein, the object is achieved by the first node, configured to operate in the communications network. The first node is configured to provision an IMS service in the communications network. The communications network is configured to comprise a first slice configured to handle a first IMS service, and a second slice configured to handle a second IMS service. The first node is further configured to obtain, from the second node configured to operate in the communications network at least one of: the first indication and the second indication. The first indication is of the first routing service instance for the third node configured to be comprised in the first slice. The third node is configured to handle the first IMS service. The second indication is of the second routing service instance for the fourth node configured to be comprised in the second slice. The fourth node is configured to handle the second IMS service. The first node is also configured to route a request, configured to be received from the fifth node configured to operate in another communications network, to one of the third node and the fourth node. One of the following may apply. With the proviso that the request configured to be received is for the first IMS service, the routing is configured to be based on the first indication configured to be obtained. With the proviso that the request configured to be received is for the second IMS service, the routing is configured to be based on the second indication configured to be obtained.

According to a fifth aspect of embodiments herein, the object is achieved by the second node. The second node is configured to operate in the communications network. The second node is configured to handle provision of an IMS service in the communications network. The communications network is configured to comprise the first slice configured to handle the first IMS service, and the second slice configured to handle the second IMS service. The second node is further configured to provide, to the first node configured to operate in the communications network, at least one of the first indication and the second indication. The first indication is of the first routing service instance the third node configured to be comprised in the first slice. The third node is configured to handle the first IMS service. The first indication is configured to enable routing of a first request for the first IMS service to the third node. The second indication is for the second routing service instance for the fourth node configured to be comprised in the second slice. The fourth node is configured to handle the second IMS service. The second indication is configured to enable routing of the second request for the second IMS service to the fourth node.

According to a sixth aspect of embodiments herein, the object is achieved by the seventh node. The seventh node is configured to operate in the communications network. The seventh node is further configured to handle provision of an IMS service in the communications network. The seventh node is configured to manage a terminating_ ICSCF. The communications network is configured to comprise the slice handling an IMS service. The seventh node is further configured to register with the second node as a provider of an IMS service. The second node is configured to manage an NRF in the communications network. The seventh node is further configured to provide the IMS service based on the registration.

By the first node obtaining the first indication and/or the second indication, the first node is enabled to identify the appropriate node in the slice handling the IMS service associated with the received request, and then route the received request to the appropriate node in the slice handling the IMS service associated with the received request. This may be performed with a simplified architecture and processing with respect to existing methods, as for example, in a DNS based system, which require instead having to statically configure diameter links among the nodes, which would increase the work effort.

By the seventh node registering with the second node, the second node may be enabled to identify the appropriate node in the slice handling a particular IMS service, and then provide to the first node the first indication and/or the second indication accordingly. In turn, by doing so, the second node thereby enables the first node to later route any incoming requests to the appropriate node in the slice handling the IMS associated with the request the first node may receive.

Examples of embodiments herein are described in more detail with reference to the accompanying drawings, according to the following description.

As part of the development of embodiments herein, a problem with exiting methods will first be identified and discussed.

As mentioned earlier in the Background section, in the context of a communications network with a plurality of IMS slices, e.g., with dual IMS slices, there is currently no technology and/or mechanism for terminating IMS service sessions, such as VoLTE and RCS, to the right IMS slice, namely, the one of the IMS slices that may be handling the service.

In the communications network supporting such plurality of IMS slices, there may be nodes that are common to the plurality of slices. At some point, communications coming into the communications network related to a specific IMS service may need to be routed to the appropriate slice supporting that specific IMS service. However, existing methods, such selective routing is not possible.

To illustrate the problem of existing methods in further detail, two particular scenarios in <NUM> networks according to which the separation and/or slicing of IMS functions may be performed will be described below: Scenario <NUM> and Scenario <NUM>. Each one of these scenarios gives rise to specific routing problems, as explained next.

In Scenario <NUM>, the operator is separating and/or slicing all IMS functions, e.g., Session Initiation Protocol - Application Server (SIP-AS), Proxy-Call Session Control Function (P-CSCF), Serving-Call Session Control Function (S-CSCF), IMS- Home Subscriber Server (IMS-HSS), between the dual IMS slices, except for the operator's IMS network ingress and egress point of presence Interconnection Border Control Function (IBCF) entity with foreign IMS networks.

This common IBCF may receive a SIP Request for VoLTE or RCS from a node in a foreign network over a Network to Network Interface (NNI).

When the operator's dual IMS slices has one terminating, Interrogating-Call Session Control Function (I-CSCF) function each, the IBCF may be understood to need to route the SIP request only to one of them, but never to both.

A problem arises then for the common IBCF to know which one of them to select for onwards routing.

In Scenario <NUM>, the operator is separating and/or slicing all IMS functions between the dual IMS slices except for the aforementioned IMS IBCF entity, but also the IMS-HSS and the terminating_I-CSCF function. That is, in Scenario <NUM>, these three may be understood to be common resources serving the dual IMS slices.

Upon a received SIP Request for VoLTE or RCS over NNI, the common IBCF may route the SIP request to the common terminating_I-CSCF function.

When the operator's dual IMS slices have one Serving-CSCF (S-CSCF) function each, said terminating_I-CSCF may be understood to need to select a S-CSCF instance and route only to that selected S-CSCF, but never both.

A problem arises then for the common terminating_I-CSCF to know which one of the two service-CSCFs to select for routing purposes.

Several embodiments are comprised herein, which address these problems of the existing methods. Embodiments herein may be understood to relate to a terminating routing policy framework in dual IMS core networks and/or slices.

Embodiments herein may solve the problem of existing methods by utilizing the benefits of the currently defined 3GPP Service Based Architecture (SBA) based 5GC core network.

The embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which examples are shown. In this section, embodiments herein are illustrated by exemplary embodiments. It should be noted that these embodiments are not mutually exclusive. All possible combinations are not described to simplify the description. Components from one embodiment or example may be tacitly assumed to be present in another embodiment or example and it will be obvious to a person skilled in the art how those components may be used in the other exemplary embodiments.

<FIG> depicts two non-limiting examples, in panels "a" and "b", respectively, of a communications network <NUM>, in which embodiments herein may be implemented. In some example implementations, such as that depicted in the non-limiting example of <FIG>), the communications network <NUM> may be a computer network. In other example implementations, such as that depicted in the non-limiting example of <FIG>), the communications network <NUM> may be implemented in a telecommunications network <NUM>, sometimes also referred to as a cellular radio system, cellular network or wireless communications system. In some examples, the telecommunications network <NUM> may comprise network nodes which may serve receiving nodes, such as wireless devices, with serving beams.

In some examples, the telecommunications network <NUM> may for example be a network such as <NUM> system, or Next Gen network or an Internet service provider (ISP)-oriented network. The telecommunications network <NUM> may also support other technologies, such as a Long-Term Evolution (LTE) network, e.g. LTE Frequency Division Duplex (FDD), LTE Time Division Duplex (TDD), LTE Half-Duplex Frequency Division Duplex (HD-FDD), LTE operating in an unlicensed band, Wideband Code Division Multiple Access (WCDMA), Universal Terrestrial Radio Access (UTRA) TDD, GSM/Enhanced Data Rate for GSM Evolution (EDGE) Radio Access Network (GERAN) network, Ultra-Mobile Broadband (UMB), EDGE network, network comprising of any combination of Radio Access Technologies (RATs) such as e.g. Multi-Standard Radio (MSR) base stations, multi-RAT base stations etc., any 3rd Generation Partnership Project (3GPP) cellular network, Wireless Local Area Network/s (WLAN) or WiFi network/s, Worldwide Interoperability for Microwave Access (WiMax), IEEE <NUM>. <NUM>-based low-power short-range networks such as IPv6 over Low-Power Wireless Personal Area Networks (6LowPAN), Zigbee, Z-Wave , Bluetooth Low Energy (BLE), or any cellular network or system.

Although terminology from Long Term Evolution (LTE)/<NUM> has been used in this disclosure to exemplify the embodiments herein, this should not be seen as limiting the scope of the embodiments herein to only the aforementioned system. Other wireless systems, support similar or equivalent functionality may also benefit from exploiting the ideas covered within this disclosure. In future radio access, e.g., in the sixth generation (<NUM>), the terms used herein may need to be reinterpreted in view of possible terminology changes in future radio access technologies.

A plurality of nodes are depicted in <FIG>, a first node <NUM>, a second node <NUM>, a third node <NUM>, a fourth node <NUM>, a fifth node <NUM>, a sixth node <NUM>, and a seventh node <NUM>. The first node <NUM>, the second node <NUM>, the third node <NUM>, the fourth node <NUM>, the sixth node <NUM> and the seventh node <NUM> are comprised in the communications network <NUM>. The fifth node <NUM> is comprised in another communications network <NUM>. The another communications network <NUM> may be understood to be enabled to have a similar description to that of the communications network <NUM>.

Each of the first node <NUM>, the second node <NUM>, the third node <NUM>, the fourth node <NUM>, the fifth node <NUM>, the sixth node <NUM> and the seventh node <NUM> may be understood, respectively, as a first computer system or server, a second computer system or server, a third computer system or server, a fourth computer system or server, a fifth computer system or server, a sixth computer system or server, and a seventh computer system or server. Any of the first node <NUM>, the second node <NUM>, the third node <NUM>, the fourth node <NUM>, the fifth node <NUM>, the sixth node <NUM> and the seventh node <NUM> may be implemented as a standalone server in e.g., a host computer in the cloud <NUM>, as depicted in the non-limiting example of <FIG>). In other examples, any of the first node <NUM>, the second node <NUM>, the third node <NUM>, the fourth node <NUM>, the fifth node <NUM>, the sixth node <NUM> and the seventh node <NUM> may be a distributed node or distributed server, such as a virtual node in the cloud <NUM>, and may perform some of its respective functions being locally, e.g., by a client manager, and some of its functions in the cloud <NUM>, by e.g., a server manager. In other examples, any of the first node <NUM>, the second node <NUM>, the third node <NUM>, the fourth node <NUM>, the fifth node <NUM>, the sixth node <NUM> and the seventh node <NUM> may perform its functions entirely on the cloud <NUM>, or partially, in collaboration or collocated with a radio network node. Yet in other examples, any of the first node <NUM>, the second node <NUM>, the third node <NUM>, the fourth node <NUM>, the fifth node <NUM>, the sixth node <NUM> and the seventh node <NUM> may also be implemented as processing resource in a server farm. Any of the first node <NUM>, the second node <NUM>, the third node <NUM>, the fourth node <NUM>, the fifth node <NUM>, the sixth node <NUM> and the seventh node <NUM> may be under the ownership or control of a service provider, or may be operated by the service provider or on behalf of the service provider. Typically, first node <NUM>, the second node <NUM>, the third node <NUM>, the fourth node <NUM>, the sixth node <NUM>, and the seventh node <NUM> may be operated by a same service provider, whereas the fifth node <NUM> may be operated by another service provider.

Any of the first node <NUM>, the second node <NUM>, the third node <NUM>, the fourth node <NUM>, the sixth node <NUM>, and the seventh node <NUM> may be a core network node in a core network <NUM>, which may be e.g., a 3GPP SBA based 5GC core network. Any of the first node <NUM>, the second node <NUM>, the third node <NUM>, the fourth node <NUM>, the sixth node <NUM> and the seventh node <NUM> may be understood to have a capability to support provision of one or more IMS services.

The first node <NUM> may be understood to be common to a first slice handling a first IMS service, and a second slice handling a second IMS service, and have a capability to route communications within the communications network <NUM> to provide an IMS service. In some embodiments, such as those described later for the Scenario <NUM>, the first node <NUM>, may be an IBCF. In other embodiments, such as those described later for the Scenario <NUM>, the first node <NUM>, may be a terminating I-CSCF.

The second node <NUM> may be understood to be common to the first slice handling the first IMS service, and the second slice handling the second IMS service, and have a capability to provide information regarding IMS services supported in the communications network <NUM>. For example, the second node <NUM> may be a database, or repository function. In some embodiments, such as those described later for the Scenario <NUM>, the second node <NUM>, may be an NRF. In other embodiments, such as those described later for the Scenario <NUM>, the second node <NUM>, may be an IMS-HSS.

The third node <NUM> may be understood to be specific to the first slice handling the first IMS service in the communications network <NUM>. In some embodiments, such as those described later for the Scenario <NUM>, the third node <NUM>, may be a first terminating_ ICSCF. In other embodiments, such as those described later for the Scenario <NUM>, the third node <NUM>, may be a first S-CSCF.

The fourth node <NUM> may be understood to be specific to the second slice handling the second IMS service in the communications network <NUM>. In some embodiments, such as those described later for the Scenario <NUM>, the fourth node <NUM>, may be a second terminating_ ICSCF. In other embodiments, such as those described later for the Scenario <NUM>, the fourth node <NUM>, may be a second S-CSCF.

The seventh node <NUM> may be understood to refer to any of the third node <NUM> and the fourth node <NUM>.

The fifth node <NUM> may be a node having the capability of sending one or more requests to the communications network <NUM> for provision of one or more IMS services.

The sixth node <NUM> may be a node having the capability of storing information regarding IMS services supported in the communications network <NUM>. For example, the sixth node <NUM> may be a database, or repository function. In some embodiments, such as those described later for the Scenario <NUM>, the sixth node <NUM>, may be an NRF.

In some embodiments, any the first node <NUM>, the second node <NUM>, the third node <NUM>, the fourth node <NUM>, the sixth node <NUM> and the seventh node <NUM>, may be independent and separated nodes. In other embodiments, any the first node <NUM>, the second node <NUM>, the third node <NUM>, the fourth node <NUM>, the sixth node <NUM> and the seventh node <NUM> may be co-located, or be the same node.

It may be understood that any of the communications network <NUM> and the another communications network <NUM> may comprise additional nodes. All the possible combinations are not depicted in <FIG> to simplify the Figure.

The communications network <NUM> may comprise a plurality of communication devices, whereof a communication device <NUM> is depicted in the non-limiting example scenario of <FIG>. The communications network <NUM> may also comprise other communication devices. The communication device <NUM> may be a UE or a Customer Premises Equipment (CPE) which may be understood to be enabled to communicate data, with another entity, such as a server, a laptop, a Machine-to-Machine (M2M) device, device equipped with a wireless interface, or any other radio network unit capable of communicating over a wired or radio link in a communications system such as the communications network <NUM>. The communication device <NUM> may be also e.g., a mobile terminal, wireless device, wireless terminal and/or mobile station, mobile telephone, cellular telephone, or laptop, just to mention some further examples. The communication device <NUM> may be, for example, portable, pocket-storable, hand-held, computer-comprised, a sensor, camera, or a vehicle-mounted mobile device, enabled to communicate voice and/or data, via a RAN, with another entity, such as a server, a laptop, a Personal Digital Assistant (PDA), or a tablet computer, sometimes referred to as a tablet with wireless capability, or simply tablet, a Machine-to-Machine (M2M) device, a device equipped with a wireless interface, such as a printer or a file storage device, modem, Laptop Embedded Equipped (LEE), Laptop Mounted Equipment (LME), USB dongles or any other radio network unit capable of communicating over a wired or radio link in the communications network <NUM>. The communication device <NUM> may be enabled to communicate wirelessly in the communications network <NUM>. The communication may be performed e.g., via a RAN and possibly one or more core networks, comprised within the communications network <NUM>.

The communications network <NUM> may comprise a plurality of radio network nodes, whereof a radio network node <NUM>, e.g., an access node, or radio network node, such as, for example, the radio network node, depicted in <FIG>). The telecommunications network <NUM> may cover a geographical area, which in some embodiments may be divided into cell areas, wherein each cell area may be served by a radio network node, although, one radio network node may serve one or several cells. In the non-limiting example of <FIG>, the radio network node <NUM> serves a cell <NUM>. The radio network node <NUM> may be e.g., a gNodeB. That is, a transmission point such as a radio base station, for example an eNodeB, or a Home Node B, a Home eNode B or any other network node capable to serve a wireless device, such as the communications device <NUM> in the communications network <NUM>. The radio network node <NUM> may be of different classes, such as, e.g., macro eNodeB, home eNodeB or pico base station, based on transmission power and thereby also cell size. In some examples, the radio network node may serve receiving nodes with serving beams. The radio network node <NUM> may support one or several communication technologies, and its name may depend on the technology and terminology used. The radio network node <NUM> may be directly connected to one or more core networks in the telecommunications network <NUM>.

The first node <NUM> is configured to communicate within the communications network <NUM> with the second node <NUM> over a first link <NUM>. The first node <NUM> may be configured to communicate with the third node <NUM> within the communications network <NUM> over a second link <NUM>. The first node <NUM> may be configured to communicate with the fourth node <NUM> within the communications network <NUM> over a third link <NUM>. The second node <NUM> may be configured to communicate with the third node <NUM> within the communications network <NUM> over a fourth link <NUM>. The second node <NUM> may be configured to communicate with the fourth node <NUM> within the communications network <NUM> over a fifth link <NUM>. The first node <NUM> may be configured to communicate within the communications network <NUM> with the sixth node <NUM> over a sixth link <NUM>. The second node <NUM> may be configured to communicate within the communications network <NUM> with the fifth node <NUM> over an eighth link <NUM>. The core network <NUM> may be configured to communicate with the radio network node <NUM> over a ninth link <NUM>. The radio network node <NUM> may be configured to communicate with the communications device <NUM> over a tenth link <NUM>. The reference numerals for some of the links are only illustrated in panel a) to simplify <FIG>.

Any of the links just described may be e.g., a radio link, an infrared link, or a wired link.

Any of the links described may be a direct link or may be comprised of a plurality of individual links, wherein it may go via one or more computer systems or one or more core networks, which are not depicted in <FIG>, or it may go via an optional intermediate network. The intermediate network may be one of, or a combination of more than one of, a public, private or hosted network; the intermediate network, if any, may be a backbone network or the Internet; in particular, the intermediate network may comprise two or more sub-networks, which is not shown in <FIG>.

In general, the usage of "first", "second", "third", "fourth", "fifth", "sixth", "seventh", "eighth", "ninth" and/or "tenth" herein may be understood to be an arbitrary way to denote different elements or entities, and may be understood to not confer a cumulative or chronological character to the nouns they modify.

Embodiments of method performed by the first node <NUM>, will now be described with reference to the flowchart depicted in <FIG>. The method may be understood to be for handling provision of an Internet Protocol Multimedia Subsystem (IMS) service in the communications network <NUM>. The first node <NUM> operates in the communications network <NUM>.

The communications network <NUM> may be understood to support provision of multiple IMS services, and to handle each of these IMS services with a separate slice. Accordingly, the communications network <NUM> comprises a first slice handling a first IMS service, and a second slice handling a second IMS service.

In some embodiments, the first IMS service may be Voice Over Long Term Evolution (VoLTE). In some embodiments, the second IMS service may be Rich Communication Services (RCS).

It may be understood that the communications network <NUM> may support other IMS services, or further IMS services, and that each may be handled by a respective slice.

The method may comprise the actions described below. In some embodiments some of the actions may be performed. In some embodiments all the actions may be performed. In <FIG>, optional actions are indicated with dashed boxes. One or more embodiments may be combined, where applicable. All possible combinations are not described to simplify the description. It should be noted that the examples herein are not mutually exclusive. Components from one example may be tacitly assumed to be present in another example and it will be obvious to a person skilled in the art how those components may be used in the other examples.

As explained earlier in relation to <FIG>, the first node <NUM> may be understood to have a capability to route communications within the communications network <NUM> to provide or support an IMS service. In the course of operations of the communications network <NUM>, the first node <NUM> may receive requests for provision of different IMS services. The first node <NUM> may then need to appropriately route each of the received requests to the slice in the communications network <NUM> that may have been allocated to handle the particular IMS service associated with the received request.

In order for the first node <NUM> to eventually route incoming requests to a node within the slice dedicated to the IMS service the received request may be about, in this Action <NUM>, the first node <NUM> may send <NUM> a query, or a discovery request, to the second node <NUM>, for at least one of a first indication and a second indication.

The first indication may be of a first routing service instance for the third node <NUM> comprised in the first slice. The third node <NUM>, as described earlier, may be handling the first IMS service, e.g., VoLTE.

A service instance may be understood as a network function service instance, that is, an identifiable instance of a network function service. A particular, non-limiting description of an NF service instance may be found on 3GPP <NUM> Version <NUM>. <NUM>, section <NUM>.

A routing service may be understood as a function which may select a path for network traffic towards its destination, e.g., as a NF providing routing service.

Therefore, a routing service instance may be understood as an identifiable instance of the routing NF service.

The second indication may be of a second routing service instance for the fourth node <NUM> comprised in the second slice. The fourth node <NUM>, as described earlier, may be handling the second IMS service, e.g., RCS.

The query may have been sent after receiving a request for an IMS service from, e.g., the another communications network <NUM>.

In some examples, the received request, e.g., a SIP request, may comprise an identifier (ID) for the IMS service. For example, the identifier may be a service-ID. The service-ID may be in the format of an IMS Communication Service ID (ICSI), see 3GPP <NUM>, v, <NUM>, section <NUM>.

In some examples of the second group of embodiments, the received request may be the a SIP request e.g. SIP INVITE comprising an IMS service- identifier (ID) for either VoLTE or RCS.

Accordingly, in some examples, the query the first node <NUM> may send in this Action <NUM> may also comprise an identifier for one of the first IMS service and the second IMS service, which may be the service identifier that may have been comprised in the received request from the another communications network <NUM>.

In a first group of embodiments, such as those corresponding to Scenario <NUM>, the first node <NUM> may manage an Interconnection Border Control Function (IBCF), and the second node <NUM> may manage a Network Repository Function (NRF).

In some embodiments of the first group of embodiments, the third node <NUM> may be a first terminating_ ICSCF.

In some of the first group of embodiments, the fourth node <NUM> may be a second ICSCF.

In some embodiments, e.g., such as those of the first group of embodiments, the first indication may be a first routing service instance address and the second indication may be a second routing service instance address. Accordingly, in some embodiments, e.g., such as those pertaining to Scenario <NUM>, the discovery request may be for a routing service instance address of a terminating_I-CSCF for a particular IMS, e.g., for a routing service instance address of a terminating_I-CSCF VoLTE and/or for a routing service instance address of an RCS service instance address.

The address may be, e.g., an IP address or a Fully Qualified Domain Name (FQDN).

Accordingly, in some embodiments, e.g., such as those pertaining to Scenario <NUM>, the discovery request may be for a routing service instance address of a terminating_I-CSCF for a particular IMS, e.g., for a routing service instance address of a terminating_I-CSCF VoLTE and/or for a routing service instance address of an RCS service instance address.

In a second group of embodiments, such as those corresponding to Scenario <NUM>, the first node <NUM> may manage a terminating_I-CSCF, and the second node <NUM> may manage an IMS-HSS. In some examples, the first node <NUM>, e.g., the terminating_I-CSCF, may have discovered the service of the second node <NUM>, e.g., the IMS-HSS, from an NRF.

In some embodiments of the second group of embodiments, the query that may be sent in this Action <NUM> may be a location information query.

In some embodiments of the second group of embodiments, the third node <NUM> may be a first S-CSCF.

In some of the second group of embodiments, the fourth node <NUM> may be a second S-CSCF.

The sending in this Action <NUM> may be performed, via the first link <NUM>.

In some embodiments of the second group of embodiments, the sending in this Action <NUM> may be over one of: a) an SBI N70 interface, and b) a Cx/Diameter protocol operation. For example, if the communications network <NUM> is not upgraded for SBA interfaces, instead of using the N70 reference point, the first node <NUM> may use a legacy Cx/Diameter protocol operation 'LIR' towards the second node <NUM>.

By sending the query, or the discovery request, in this Action <NUM>, the first node <NUM> may be able to obtain the requested indications, and thereby be enabled to then route any incoming requests, e.g., a current session request, to the appropriate node in the slice handling the IMS associated with the received request.

In this Action <NUM>, the first node <NUM>, obtains, from the second node <NUM> operating in the communications network <NUM> at least one of: a) the first indication of the first routing service instance for the third node <NUM> comprised in the first slice, the third node <NUM> handling the first IMS service, and b) the second indication of the second routing service instance for the fourth node <NUM> comprised in the second slice, the fourth node <NUM> handling the second IMS service.

In some embodiments wherein Action <NUM> may have been performed, the obtaining in this Action <NUM> may be in response to the sent query.

In some embodiments, e.g., those of the second group of embodiments, one of the following alternatives may apply. According to a first alternative, with the proviso that the query that may have been sent in Action <NUM> may comprise an identifier for one of the first IMS service and the second IMS service, only the one of the first indication and the second indication corresponding to the IMS service identified by the sent identifier may be obtained. According to a second alternative, with the proviso that the query that may have been sent in Action <NUM> may lack an identifier for one of the first IMS service and the second IMS service, both of the first indication and the second indication may be obtained.

As mentioned earlier the identifier may be a service-ID.

For example, in some of the second group of embodiments, the first node <NUM> may or may not have included the service identifier which in the query. If not included, the second node <NUM> may return each serving-CSCF instances of the two dual IMS slices. The first indication and the second indication may then be set to indicate which IMS service, VoLTE or RCS, the third node <NUM>, and the fourth node <NUM> may be serving, respectively. If included, the second node <NUM> may return just the indication for the one of the third node <NUM>, and the fourth node <NUM> associated with the service identifier.

In examples wherein the communications network <NUM> may use non-SBA interfaces, if the service identifier is not included in request, the first node <NUM> may obtain each of the first indication and the second indication. Each of the first indication and the second indication may then be set to indicate which IMS service, VoLTE or RCS, the third node <NUM>, and the fourth node <NUM> may be serving, respectively.

If the service identifier is included in the request, the first node <NUM> may just obtain the indication for the one of the third node <NUM>, and the fourth node <NUM> associated with the service identifier.

Obtaining, may comprise receiving, collecting or gathering, e.g., via the first link <NUM>.

By obtaining the first indication and/or the second indication in this Action <NUM>, the first node <NUM> may be enabled to identify the appropriate node in the slice handling the IMS associated with the received request, and then route any incoming requests, e.g., the current session request, to the appropriate node in the slice handling the IMS associated with the received request.

In this Action <NUM>, the first node <NUM> may store, e.g., in a memory, the obtained at least one of the first indication and the second indication.

In this this Action <NUM>, the first node <NUM>, routes a request, received from the fifth node <NUM> operating in the another communications network <NUM>, to one of the third node <NUM> and the fourth node <NUM>. One of the following alternatives may apply: With the proviso that the received request is for the first IMS service, the routing in this Action <NUM> is based on the obtained first indication. With the proviso that the received request is for the second IMS service, the routing <NUM> is based on the obtained second indication.

In the embodiments wherein Action <NUM> may have been performed, the routing in this Action <NUM> may be based on the stored first indication and the second indication.

For example, in some embodiments of the first group of embodiments, wherein the first node <NUM> may be an IBCF, the received request may be a terminating VoLTE SIP request or a terminating RCS request from a foreign network such as the second communications network <NUM>. Upon reception of the request, the first node <NUM> may then, in this Action <NUM>, route the SIP request, to the first terminating_I-CSCF instance, or the second terminating_I-CSCF instance discovered in Action <NUM>, pertaining to the SIM service associated with the received request.

In other examples, in some of the embodiments of the second group of embodiments, wherein the first node <NUM> may be a terminating_I-CSCF, the received request may be the SIP request, e.g., the SIP INVITE comprising the IMS service-identifier (ID) for either VoLTE or RCS described earlier. The SIP request may have been initially received by an IBCF in the communications network <NUM>, and then onward routed to the first node <NUM>.

In this Action <NUM>, the first node <NUM> may onward route the received SIP request to the serving-CSCF instance, e.g., serving VoLTE or RCS, that may have been indicated by the second node <NUM> in Action <NUM>.

By routing the request based on the first indication or the second indication in this Action <NUM>, the first node <NUM> may be enabled to route the incoming requests, e.g., the current session request, to the appropriate node in the slice handling the IMS associated with the received request. This may be performed with a simplified architecture and processing with respect to existing methods, as for example, in a DNS based system, which require instead having to statically configure links among the nodes, which would increase the work effort.

For example, implementing the embodiments herein in the IBCF, as may be done in the embodiments of the first group of embodiments, such as those of Scenario <NUM>, may be understood to ensure that a single ingress point may be offered to foreign networks and/or IPXs thus reducing OPEX cost for the interworking partners.

Embodiments of a method performed by the second node <NUM>, will now be described with reference to the flowchart depicted in <FIG>. The second node <NUM> operates in the communications network <NUM>. The method is being for handling provision of an IMS service in the communications network <NUM>.

As stated earlier, the communications network <NUM> may be understood to support provision of multiple IMS services, and to handle each of these IMS services with a separate slice. Accordingly, the communications network <NUM> comprises the first slice handling the first IMS service, and the second slice handling the second IMS service.

The method comprises the following actions. Several embodiments are comprised herein. In <FIG>, optional actions are indicated with dashed boxes. One or more embodiments may be combined, where applicable. All possible combinations are not described to simplify the description. It should be noted that the examples herein are not mutually exclusive. Components from one example may be tacitly assumed to be present in another example and it will be obvious to a person skilled in the art how those components may be used in the other examples.

The detailed description of some of the following corresponds to the same references provided above, in relation to the actions described for the first node <NUM>, and will thus not be repeated here to simplify the description. For example, in some embodiments, the first IMS service may be VoLTE. In some embodiments, the second IMS service may be RCS.

In some embodiments, e.g., some embodiments of the first group of embodiments, the second node <NUM>, may, in this Action <NUM>, obtain at least one of: a first registration request and a second registration request. The first registration request may be from the third node <NUM> as a provider of the first IMS service. The second registration request may be from the fourth node <NUM> as a provider of the second IMS service.

The obtaining in this Action <NUM> may be implemented, e.g., via the fourth link <NUM>, for the first registration request, and via the fifth link <NUM>, for the second registration request.

By obtaining the first registration request and/or the second registration request, the second node <NUM> may be enabled to identify the appropriate node in the slice handling a particular IMS service, and then provide to the first node <NUM> the first indication and/or the second indication. In turn, by doing so, the second node <NUM> may thereby enable the first node <NUM> to later route any incoming requests to the appropriate node in the slice handling the IMS associated with the request the first node <NUM> may receive.

In this Action <NUM>, the second node <NUM> may determine at least one of the first indication and the second indication. This determination may be based, respectively, on the obtained first registration request and the obtained second registration request in Action <NUM>.

Determining may be understood as calculating, predicting, estimating, or similar.

In some embodiments of the first group of embodiments, the first node <NUM> may manage an IBCF, and the second node <NUM> may manage an NRF.

In the first group of embodiments, such as those corresponding to Scenario <NUM>, the third node <NUM> may be a first terminating_ ICSCF.

In some embodiments of the first group of embodiments, the first indication may be a first routing service instance address and the second indication may be a second routing service instance address.

In some embodiments of the second group of embodiments, the first node <NUM> may manage a terminating_I-CSCF, and the second node <NUM> may manage an IMS-HSS.

In the second group of embodiments, such as those corresponding to Scenario <NUM>, the third node <NUM> may be a first S-CSCF.

By determining the first indication and/or the second indication, the second node <NUM> may then be able to provide at least one of these indications to the first node <NUM>, and thereby enable the first node <NUM> to later route any incoming requests to the appropriate node in the slice handling the IMS associated with the request the first node <NUM> may receive.

In some embodiments, e.g., some embodiments of the second group of embodiments, the second node <NUM> may, in this Action <NUM>, register with the sixth node <NUM> operating in the communications network <NUM>. The second node <NUM> may be an IMS-HSS. The sixth node <NUM> may be, for example an NRF.

By registering with the sixth node <NUM>, the second node <NUM> may then enable the first node <NUM> to discover it via the sixth node <NUM>, and thereby also enable the first node <NUM> to query, or send the discovery request to, the second node <NUM> for the first indication and/or the second indication.

In some embodiments, the second node <NUM> may, in this Action <NUM>, receive the query or the discovery request from the first node <NUM>, for at least one of the first indication and the second indication.

As stated earlier, in some examples, the query may comprise an identifier (ID) for the IMS service. For example, the identifier may be a service-ID. The service-ID may be in the format of an ICSI.

In some embodiments, e.g., some embodiments of the second group of embodiments, the query may be for the location of at least one of the third node <NUM> and the fourth node <NUM>. The query may be received based on the registration performed in Action <NUM>.

The receiving in this Action <NUM> may be performed, via the first link <NUM>.

In some embodiments of the second group of embodiments, the receiving in this Action <NUM> may be over one of: a) the SBI N70 interface, and b) the Cx/Diameter protocol operation.

The second node <NUM>, in this Action <NUM>, provides, to the first node <NUM> operating in the communications network <NUM>, the at least one of the first indication and the second indication. As described earlier, the first indication is of the first routing service instance for the third node <NUM> comprised in the first slice. The third node <NUM> handles the first IMS service. The first indication enables routing of the first request for the first IMS service to the third node <NUM>. The second indication is for the second routing service instance for the fourth node <NUM> comprised in the second slice. The fourth node <NUM> handles the second IMS service. The second indication enables routing of the second request for the second IMS service to the fourth node <NUM>.

Providing, may comprise sending, e.g., via the first link <NUM>.

In embodiments wherein Action <NUM> may have been performed, the providing in this Action <NUM> may be performed in response to the received query.

In some embodiments, such as those of the second group of embodiments, one of the following alternatives may apply. According to a first alternative, with the proviso that the query that may have been received in Action <NUM> may comprise an identifier for one of the first IMS service and the second IMS service, only the one of the first indication and the second indication corresponding to the IMS service identified by the sent identifier may be provided. According to a second alternative, with the proviso that the query that may have been received in Action <NUM> may lack an identifier for one of the first IMS service and the second IMS service, both of the first indication and the second indication may be provided.

As mentioned earlier, the identifier may be a service-ID.

In embodiments wherein Action <NUM> may have been performed, the provided first indication may be based on the first registration request.

Similarly, the provided second indication may be based on the second registration request.

Embodiments of a method performed by the seventh node <NUM>, will now be described with reference to the flowchart depicted in <FIG>. The method is for handling provision of an IMS service in the communications network <NUM>. The seventh node <NUM> operates in the communications network <NUM>. The seventh node <NUM> manages a terminating_ ICSCF. The communications network <NUM> comprises at least a slice handling an IMS service.

The method comprises the following actions. Several embodiments are comprised herein. One or more embodiments may be combined, where applicable. All possible combinations are not described to simplify the description. It should be noted that the examples herein are not mutually exclusive. Components from one example may be tacitly assumed to be present in another example and it will be obvious to a person skilled in the art how those components may be used in the other examples.

The detailed description of some of the following corresponds to the same references provided above, in relation to the actions described for the first node <NUM>, and will thus not be repeated here to simplify the description. For example, it may be understood that the communications network <NUM> may support other IMS services, or further IMS services, and that each may be handled by a respective slice. Accordingly, the communications network <NUM> may comprise the first slice handling the first IMS service, and the second slice handling the second IMS service. In some embodiments, the first IMS service may be Voice Over Long Term Evolution (VoLTE). In some embodiments, the second IMS service may be Rich Communication Services (RCS). The communications network <NUM> may comprise one of the third node <NUM> and the fourth node <NUM>, different from the seventh node <NUM>. The other or the third node <NUM> and the fourth node <NUM> that may be additionally comprised in the communications network <NUM> may handle another IMS service not handled by the seventh <NUM>.

In this Action <NUM>, the seventh node <NUM> registers with the second node <NUM> as a provider of an IMS service. The second node <NUM> manages an NRF in the communications network <NUM>.

As indicated earlier, the seventh node <NUM> may be the third node <NUM>, which may be handling the first IMS service, e.g., VoLTE. In other example, the seventh node <NUM> may be the fourth node <NUM>, which may be handling the second IMS service, e.g., RCS.

In agreement with this, the registering in this Action <NUM> may comprise one of the following alternatives. In a first alternative, the registering may comprise sending the first registration request from the seventh node <NUM> as a provider of the first IMS service, the first IMS service being, e.g., VoLTE. In a second alternative, the registering may comprise, sending the second registration request from the seventh node <NUM> as a provider of the second IMS service, the second IMS service being, e.g., RCS.

Accordingly, in this Action <NUM>, an I-CSCF service instance of a VoLTE IMS slice may register its terminating routing service for VoLTE to the NRF. In other examples, another I-CSCF service instance, of the RCS IMS slice, may register its RCS terminating routing service for RCS to the NRF.

In this Action <NUM>, the seventh node <NUM> provides, that is, supports the provision of, the IMS service based on the registration. If the seventh node <NUM> registered for VoLTE, it may support provision of VoLTE, and it registered for RCS, it may support provision of RCS.

The methods just described as being implemented by the first node <NUM>, the second node <NUM> and the seventh node <NUM> will now be described in further detail with specific non-limiting examples in the next four figures, based on the already mentioned Scenario <NUM> and Scenario <NUM>.

<FIG> is a schematic block diagram depicting a non-limiting example of an architecture the communications network <NUM> may have in the first group of embodiments herein, in accordance with Scenario <NUM>. In this non-limiting example, the communications network <NUM> comprises the communications device <NUM>, a radio access network represented by the radio network node <NUM>, and the core network <NUM>. The communications network <NUM> is owned by an operator having dual IMS networks and comprises the first slice <NUM> handling VoLTE, depicted as the "VoLTE slice", and the second slice <NUM> handling RCS, depicted as the "RCS slice". Each of the first slice and the second slice comprises either the third node <NUM> or the fourth node <NUM> as a Terminal I-CSCF "Term. I-CSCF", and a respective P-CSCF <NUM>, the I-CSCF a user may have registered its RCS / VoLTE service in, represented as "Reg. I-CSCF" <NUM>, S-CSCF <NUM>, SIP-AS <NUM>, a Multimedia Resource Function Processor (MRFP) <NUM>, an Originating I-CSCF, represented as "Orig. _I-CSCF" <NUM>, and IMS-HSS <NUM>. The fifth node <NUM>, e.g., in the another communications network <NUM>, sends a SIP request for either VoLTE or RCS to the first node <NUM>, here an IBCF, which may then need to route the received request to one of the third node <NUM> and the fourth node <NUM>, based on the IMS service the received request is for. The routing is performed here through the appropriate Mx interface <NUM>. An example of how this may be performed is provided in the next Figure.

<FIG> is a signalling diagram depicting a non-limiting example of how embodiments herein may be implemented in the architecture depicted in <FIG>, that is, corresponding to Scenario <NUM>. First, at "<NUM>", the third node <NUM>, an I-CSCF service instance of a VoLTE IMS slice, may register, in accordance with Action <NUM>, its terminating routing service for VoLTE to the second node <NUM>, an NRF. This may be implemented by sending the first registration request, which may be in the form of "Nnrf _REGISTER-Service:Terminating-I-CSCF (VoLTE)-Instance:y". Similarly, the fourth node <NUM>, another I-CSCF service instance, of the RCS IMS slice, may register, in accordance with Action <NUM>, its RCS terminating routing service for RCS to the second node <NUM>. This may be implemented by sending the sending registration request, which may be in the form of "Nnrf_REGISTER-Service:Terminating-ICSCF(RCS)-Instance:. The second node <NUM> receives the first registration request and the second registration request, respectively, according to Action <NUM>. Second, at "<NUM>", the first node <NUM>, the IBCF, may at start-up, put a discovery request, in accordance with Action <NUM>, to the second node <NUM>, the NRF, for a terminating_I-CSCF VoLTE routing service instance address. The query may be in the form of "Nnrf_DISCOVERYService:Terminating-ICSCF(VoLTE)" or "Nnrf _DISCOVERYservice:Terminating-/CSCF(RCS)". The second node <NUM> receives the query in agreement with Action <NUM>. The IBCF may store, in accordance with Action <NUM>, the terminating_I-CSCF (VoLTE) instance address returned by NRF for later routing usage. The same IBCF may put another discovery request, also in accordance with Action <NUM>, to NRF for a terminating I-CSCF RCS service instance address. The IBCF would store, in accordance with Action <NUM>, the terminating_I-CSCF (RCS) instance address returned by NR for later routing usage. Third, at "<NUM>", after this, upon reception of a terminating VoLTE SIP request at <NUM> from the fifth node <NUM> in a foreign network such as the another communications network <NUM>, the IBCF would route, in accordance with Action <NUM>, the SIP request, to the terminating_I-CSCF instance discovered in Action <NUM>. Fourth, at "<NUM>", upon reception of a terminating RCS request at <NUM> from the fifth node <NUM> in a foreign network such as the another communications network <NUM>, the IBCF would do onward routing, in accordance with Action <NUM>, of the SIP request, to the terminating_I-CSCF instance discovered in Action <NUM>.

<FIG> is a schematic block diagram depicting a non-limiting example of an architecture the communications network <NUM> may have in the second group of embodiments herein, in accordance with Scenario <NUM>. In this non-limiting example, the communications network <NUM> comprises the communications device <NUM>, a radio access network represented by the radio network node <NUM>, and the core network <NUM>. The communications network <NUM> is owned by an operator having dual IMS networks and comprises the first slice <NUM> handling VoLTE, depicted as the "VoLTE slice", and the second slice <NUM> handling RCS, depicted as the "RCS slice". Each of the first slice and the second slice comprises either the third node <NUM> or the fourth node <NUM> as S-CSCF, and a respective P-CSCF <NUM>, Reg. I-CSCF <NUM>, SIP-AS <NUM>, MRFP <NUM>, and Orig. _I-CSCF <NUM>. In addition, the communications network <NUM> comprises the first node <NUM> as a Terminal I-CSCF "Term. I-CSCF", the second node <NUM> as a first IMS-HSS, an IBCF <NUM> and a second IMS-HSS <NUM>. The fifth node <NUM>, e.g., in the another communications network <NUM>, sends a SIP request for either VoLTE or RCS to the IBCF <NUM>. The IBCF <NUM> sends it forward to the first node <NUM>, which may then need to route the received request to one of the third node <NUM> and the fourth node <NUM>, based on the IMS service the received request is for. The routing is performed here through the appropriate interface <NUM>. An example of how this may be performed is provided in the next Figure.

<FIG> is a signalling diagram depicting a non-limiting example of how embodiments herein may be implemented in the architecture depicted in <FIG>, that is, corresponding to Scenario <NUM>. First, at "<NUM>", the second node <NUM>, a <NUM> IMS-HSS registers, in accordance with Action <NUM>, its service to the sixth node <NUM>, here an NRF. Second, at "<NUM>", the first node <NUM>, here a Terminating_I-CSCF, discovers the IMS-HSS service from the NRF. Third, at "<NUM>", a SIP request e.g., SIP INVITE containing an IMS service-ID for either VoLTE or RCS, is received in the IBCF <NUM>, which makes onward routing of it to the terminating_I-CSCF. Fourth , at "<NUM>", the terminating_I-CSCF makes a location information query, in accordance with Action <NUM>, to the IMS-HSS discovered as of step <NUM>, over the SBI N70 interface, see 3GPP <NUM> Annex AA. <NUM> Architectural Support. The second node <NUM> receives the query in accordance with Action <NUM>. The I-CSCF may or may not include the newly introduced service-ID which may be in the format of an ICSI, see 3GPP <NUM> V <NUM>, section <NUM>. <NUM>", in the query. If not included, the IMS-HSS may return each serving-CSCF instances of the two dual IMS slices. An indication of the first indication and the second indication may need to be set to indicate which IMS service, VoLTE or RCS, the serving-CSCF is serving. If included, the IMS-HSS may return, in accordance with Action <NUM>, just the serving-CSCF instance associated with the service-ID. Fifth, at "<NUM>", the terminating_I-CSCF does onward routing, in accordance with Action <NUM>, of the SIP request to the serving-CSCF instance, serving VoLTE or RCS, obtained, in accordance with, from IMS-HSS in step <NUM>.

It may be noted that if the IMS system of the communications network <NUM> is not upgraded for SBA interfaces, some steps above may be different as follows. Instead of steps <NUM> and <NUM>, the legacy IMS method may apply for terminating_I-CSCF to find the IMS-HSS. Instead of using the N70 reference point, the terminating_I-CSCF may use the legacy Cx/Diameter protocol operation 'LIR' towards IMS-HSS to get the serving-CSCF instance.

In case of using non-SBA interfaces, the following may apply. If the service-ID is not included in the LIR, the IMS-HSS may return a response message to LIR, each serving-CSCF instances of the two dual IMS slices. An indication of the first indication and the second indication may need to be set to indicate which IMS service, VoLTE or RCS, the serving-CSCF is serving. If Service-ID is included in the LIR, the IMS-HSS may return just the serving-CSCF instance associated with the service-ID.

As a simplified overview of the foregoing for Scenario <NUM>, according to some examples of embodiments herein, an IBCF instance may be able to query an 5GC Network Function Repository Function (NRF) entity for discovery of the terminating_I-CSCF instance serving VoLTE and RCS respectively. To enable this discovery, a terminating_I-CSCF instance may be able to register itself to a 5GC NRF.

As a simplified overview of the foregoing for Scenario <NUM>, according to some examples of embodiments herein, a common IMS-HSS in a dual IMS sliced system, may, upon a location query from a terminating_I-CSCF function, be able to return two serving-CSCF instances. Moreover, the IMS-HSS may indicate which of them is serving VoLTE and which of them is serving RCS.

The terminating_I-CSCF function may then select the one that serves the received SIP requested service.

It may be noted that an alternative method may be that the location query contains the IMS service ID (ICSI). This may be considered as an order for the IMS-HSS to return only one S-CSCF instance- the one associated with that service ID.

One advantage of embodiments herein may be understood to be that there are OPEX gains for an operator by using 3GPP SBA interfaces when configuring a dual IMS core sliced network, as otherwise a lot of static configurations of diameter links between IMS functions would increase the work effort.

Another advantage of using a 5GC SBA based architecture with the embodiments disclosed herein, is that it allows automatic discovery of an IMS service consumer, e.g. IBCF in Scenario <NUM> of IMS service producers, and/or terminating_I-CSCF in Scenario <NUM>, instead of having to statically configure diameter links as in a DNS based system.

Implementing the embodiments disclosed herein in the IBCF, as disclosed for example in Scenario <NUM>, ensures that a single ingress point may be offered to foreign networks and/or IPXs thus reducing OPEX cost for the interworking partners.

<FIG> depicts two different examples in panels a) and b), respectively, of the arrangement that the first node <NUM> may comprise to perform the method actions described above in relation to <FIG>. In some embodiments, the first node <NUM> may comprise the following arrangement depicted in <FIG>. The first node <NUM> is configured to operate in the first communications network <NUM>. The first node <NUM> is configured to handle provision IMS service in the communications network <NUM>. The communications network <NUM> is configured to comprise the first slice configured to handle the first IMS service, and the second slice configured to handle the second IMS service.

Several embodiments are comprised herein. Components from one embodiment may be tacitly assumed to be present in another embodiment and it will be obvious to a person skilled in the art how those components may be used in the other exemplary embodiments. In <FIG>, optional boxes are indicated by dashed lines. The detailed description of some of the following corresponds to the same references provided above, in relation to the actions described for the first node <NUM>, and will thus not be repeated here. For example, in some embodiments, the first IMS service may be configured to be VoLTE. In some embodiments, the second IMS service may be configured to be RCS.

The first node <NUM> is configured to, e.g. by means of an obtaining unit <NUM> within the first node <NUM> configured to, obtain, from the second node <NUM> configured to operate in the communications network <NUM> at least one of the first indication and the second indication. The first indication is configured to be of the first routing service instance for the third node <NUM> configured to be comprised in the first slice. The third node <NUM> is configured to handle the first IMS service. The second indication is configured to be of the second routing service instance for the fourth node <NUM> configured to be comprised in the second slice. The fourth node <NUM> is configured to handle the second IMS service.

The first node <NUM> is also configured to, e.g. by means of a routing unit <NUM> within the first node <NUM> configured to, route a request, configured to be received from the fifth node <NUM> configured to operate in the another communications network <NUM>, to one of the third node <NUM> and the fourth node <NUM>. One of the following may apply. With the proviso that the request configured to be received is for the first IMS service, the routing is configured to be based on the first indication configured to be obtained. With the proviso that the request configured to be received is for the second IMS service, the routing is configured to be based on the second indication configured to be obtained.

In some embodiments, the first node <NUM> may be configured to, e.g. by means of a sending unit <NUM> within the first node <NUM> configured to, send the query or the discovery request to the second node <NUM>, for at least one of the first indication and the second indication. To obtain may be configured to be in response to the query configured to be sent.

In some embodiments, such as those of the first group of embodiments, at least one of: a) the third node <NUM> may be configured to be a first terminating_ ICSCF, and b) the fourth node <NUM> may be configured to be a second terminating_ ICSCF.

In some of such embodiments, the first indication may be configured to be the first routing service instance address and the second indication may be configured to be the second routing service instance address.

In some embodiments, such as those of the first group of embodiments, the first node <NUM> may be configured to manage the IBCF, and the second node <NUM> may be configured to manage the NRF.

In some embodiments, such as those of the second group of embodiments, at least one of: a) the third node <NUM> may be configured to be the first S-CSCF, and b) the fourth node <NUM> may be configured to be a second S-CSCF.

In some embodiments, such as those of the second group of embodiments, one of the following may apply: a) with the proviso that the query configured to be sent may comprise an identifier for one of the first IMS service and the second IMS service, only the one of the first indication and the second indication corresponding to the IMS service identified by the sent identifier may be configured to be obtained, and b) with the proviso that the query configured to be sent may lack an identifier for one of the first IMS service and the second IMS service, both of the first indication and the second indication may be configured to be obtained.

In some embodiments, to send is configured to be over one of: a) the SBI N70 interface, and b) the Cx/Diameter protocol operation.

In some embodiments, such as those of the second group of embodiments, the first node <NUM> may be configured to manage a terminating_I-CSCF, and the second node <NUM> may be configured to manage an IMS-HSS.

In some embodiments, the first node <NUM> may be further configured to, e.g. by means of a storing unit <NUM> within the first node <NUM> configured to, store the at least one of the first indication and the second indication configured to be obtained. In such embodiments, to route may be configured to be based on the first indication and the second indication configured to be stored.

The embodiments herein may be implemented through one or more processors, such as a processor <NUM> in the first node <NUM> depicted in <FIG>, together with computer program code for performing the functions and actions of the embodiments herein. The program code mentioned above may also be provided as a computer program product, for instance in the form of a data carrier carrying computer program code for performing the embodiments herein when being loaded into the in the first node <NUM>. One such carrier may be in the form of a CD ROM disc. It is however feasible with other data carriers such as a memory stick. The computer program code may furthermore be provided as pure program code on a server and downloaded to the first node <NUM>.

The first node <NUM> may further comprise a memory <NUM> comprising one or more memory units. The memory <NUM> is arranged to be used to store obtained information, store data, configurations, schedulings, and applications etc. to perform the methods herein when being executed in the first node <NUM>.

In some embodiments, the first node <NUM> may receive information from, e.g., the second node <NUM>, the third node <NUM>, the fourth node <NUM>, the fifth node <NUM>, the sixth node <NUM>, and/or the seventh node <NUM> through a receiving port <NUM>. In some examples, the receiving port <NUM> may be, for example, connected to one or more antennas in first node <NUM>. In other embodiments, the first node <NUM> may receive information from another structure in the system of communications networks <NUM> through the receiving port <NUM>. Since the receiving port <NUM> may be in communication with the processor <NUM>, the receiving port <NUM> may then send the received information to the processor <NUM>. The receiving port <NUM> may also be configured to receive other information.

The processor <NUM> in the first node <NUM> may be further configured to transmit or send information to e.g., the second node <NUM>, the third node <NUM>, the fourth node <NUM>, the fifth node <NUM>, the sixth node <NUM>, and/or the seventh node <NUM>, through a sending port <NUM>, which may be in communication with the processor <NUM>, and the memory <NUM>.

Those skilled in the art will also appreciate that the obtaining unit <NUM>, the routing unit <NUM>, the sending unit <NUM>, and the storing unit <NUM> described above may refer to a combination of analog and digital circuits, and/or one or more processors configured with software and/or firmware, e.g., stored in memory, that, when executed by the one or more processors such as the processor <NUM>, perform as described above. One or more of these processors, as well as the other digital hardware, may be included in a single Application-Specific Integrated Circuit (ASIC), or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a System-on-a-Chip (SoC).

Any of the obtaining unit <NUM>, the routing unit <NUM>, the sending unit <NUM>, and the storing unit <NUM> described above may be the processor <NUM> of the first node <NUM>, or an application running on such processor.

Thus, the methods according to the embodiments described herein for the first node <NUM> may be respectively implemented by means of a computer program <NUM> product, comprising instructions, i.e., software code portions, which, when executed on at least one processor <NUM>, cause the at least one processor <NUM> to carry out the actions described herein, as performed by the first node <NUM>. The computer program <NUM> product may be stored on a computer-readable storage medium <NUM>. The computer-readable storage medium <NUM>, having stored thereon the computer program <NUM>, may comprise instructions which, when executed on at least one processor <NUM>, cause the at least one processor <NUM> to carry out the actions described herein, as performed by the first node <NUM>. In some embodiments, the computer-readable storage medium <NUM> may be a non-transitory computer-readable storage medium, such as a CD ROM disc, a memory stick, or stored in the cloud space. In other embodiments, the computer program <NUM> product may be stored on a carrier containing the computer program, wherein the carrier is one of an electronic signal, optical signal, radio signal, or the computer-readable storage medium <NUM>, as described above.

The first node <NUM> may comprise an interface unit to facilitate communications between the first node <NUM> and other nodes or devices, e.g., the second node <NUM>, the third node <NUM>, the fourth node <NUM>, the fifth node <NUM>, the sixth node <NUM>, and/or the seventh node <NUM>. In some particular examples, the interface may, for example, include a transceiver configured to transmit and receive radio signals over an air interface in accordance with a suitable standard.

In other embodiments, the first node <NUM> may comprise the following arrangement depicted in <FIG>. The first node <NUM> may comprise a processing circuitry <NUM>, e.g., one or more processors such as the processor <NUM>, in the first node <NUM> and the memory <NUM>. The first node <NUM> may also comprise a radio circuitry <NUM>, which may comprise e.g., the receiving port <NUM> and the sending port <NUM>. The processing circuitry <NUM> may be configured to, or operable to, perform the method actions according to <FIG>, in a similar manner as that described in relation to <FIG>. The radio circuitry <NUM> may be configured to set up and maintain at least a wireless connection with the second node <NUM>, the third node <NUM>, the fourth node <NUM>, the fifth node <NUM>, the sixth node <NUM>, and/or the seventh node <NUM>. Circuitry may be understood herein as a hardware component.

Hence, embodiments herein also relate to the first node <NUM> operative to handle provision of an IMS service in the communications network <NUM>, the first node <NUM> being operative to operate in the communications network <NUM> wherein the communications network <NUM> comprises the first slice handling the first IMS service, and the second slice handling the second IMS service. The first node <NUM> may comprise the processing circuitry <NUM> and the memory <NUM>, said memory <NUM> containing instructions executable by said processing circuitry <NUM>, whereby the first node <NUM> is further operative to perform the actions described herein in relation to the first node <NUM>, e.g., in <FIG>.

<FIG> depicts two different examples in panels a) and b), respectively, of the arrangement that the second node <NUM> may comprise to perform the method actions described above in relation to <FIG>. In some embodiments, the second node <NUM> may comprise the following arrangement depicted in <FIG>. The second node <NUM> is configured to operate in the first communications network <NUM>. The second node <NUM> is configured to handle provision IMS service in the communications network <NUM>. The communications network <NUM> is configured to comprise the first slice configured to handle the first IMS service, and the second slice configured to handle the second IMS service.

Several embodiments are comprised herein. Components from one embodiment may be tacitly assumed to be present in another embodiment and it will be obvious to a person skilled in the art how those components may be used in the other exemplary embodiments. In <FIG>, optional boxes are indicated by dashed lines. The detailed description of some of the following corresponds to the same references provided above, in relation to the actions described for the second node <NUM>, and will thus not be repeated here. For example, in some embodiments, the first IMS service may be configured to be VoLTE. In some embodiments, the second IMS service may be configured to be RCS.

The second node <NUM> is configured to, e.g. by means of a providing unit <NUM> within the second node <NUM> configured to, provide, to the first node <NUM> configured to operate in the communications network <NUM>, at least one of: the first indication and the second indication. The first indication is configured to be of the first routing service instance for the third node <NUM> configured to be comprised in the first slice. The third node <NUM> is configured to handle the first IMS service. The first indication is configured to enable routing of the first request for the first IMS service to the third node <NUM>. The second indication is configured to be of the second routing service instance for the fourth node <NUM> configured to be comprised in the second slice. The fourth node <NUM> is configured to handle the second IMS service. The second indication is configured to enable routing of a second request for the second IMS service to the fourth node <NUM>.

The second node <NUM>, in some embodiments, may also be configured to, e.g. by means of a receiving unit <NUM> within the second node <NUM> configured to, receive the query or the discovery request from the first node <NUM>, for at least one of the first indication and the second indication. In some of such embodiments, to provide may be in response to the query configured to be received.

In some embodiments, the second node <NUM> may be configured to, e.g. by means of an obtaining unit <NUM> within the second node <NUM> configured to, obtain at least one of: a) the first registration request from the third node <NUM> as a provider of the first IMS service, wherein the first indication configured to be obtained may be configured to be based on the first registration request, and b) the second registration request from the fourth node <NUM> as a provider of the second IMS service, wherein the second indication configured to be provided may be configured to be based on the second registration request.

In some embodiments, the second node <NUM> may be configured to, e.g. by means of a determining unit <NUM> within the second node <NUM> configured to, determine at least one of the first indication and the second indication, based, respectively, on the first registration request configured to be obtained and the second registration request configured to be obtained.

In some embodiments, such as those of the first group of embodiments, at least one of the following may apply: a) the third node <NUM> may be configured to be a first terminating_ ICSCF, and b) the fourth node <NUM> may be configured to be a second terminating_ ICSCF.

In some embodiments, the first indication may be configured to be the first routing service instance address and the second indication may be configured to be the second first routing service instance address.

In some embodiments, such as those of the first group of embodiments, the first node <NUM> may be configured to manage an IBCF, and the second node <NUM> may be configured to manage an NRF.

In some embodiments, such as those of the second group of embodiments, at least one of the following may apply: a) the third node <NUM> may be configured to be a first serving ICSF, and b) the fourth node <NUM> may be configured to be a second ICSF.

In some embodiments, the second node <NUM> may be configured to, e.g. by means of a registering unit <NUM> within the second node <NUM> configured to, register with the sixth node <NUM> configured to operate in the communications network <NUM>. In some of such embodiments, the query may be configured to be for the location of at least one of the third node <NUM> and the fourth node <NUM>. The query may be configured to be received based on the registration.

In some embodiments, at least one of the following may apply: a) with the proviso that the query configured to be received may be configured to comprise the identifier for one of the first IMS service and the second IMS service, only the one of the first indication and the second indication corresponding to the IMS service identified by the received identifier may be configured to be provided, and b) with the proviso that the query configured to be received may lack the identifier for one of the first IMS service and the second IMS service, both of the first indication and the second indication may be configured to be provided.

In some embodiments, to receive may be configured to be over one of: a) the SBI N70 interface, and b) the Cx/Diameter protocol operation.

The first node <NUM> may be configured to manage a terminating_I-CSCF, and second node <NUM> may be configured to manage an IMS-HSS.

The embodiments herein may be implemented through one or more processors, such as a processor <NUM> in the second node <NUM> depicted in <FIG>, together with computer program code for performing the functions and actions of the embodiments herein. The program code mentioned above may also be provided as a computer program product, for instance in the form of a data carrier carrying computer program code for performing the embodiments herein when being loaded into the in the second node <NUM>. One such carrier may be in the form of a CD ROM disc. It is however feasible with other data carriers such as a memory stick. The computer program code may furthermore be provided as pure program code on a server and downloaded to the second node <NUM>.

The second node <NUM> may further comprise a memory <NUM> comprising one or more memory units. The memory <NUM> is arranged to be used to store obtained information, store data, configurations, schedulings, and applications etc. to perform the methods herein when being executed in the second node <NUM>.

In some embodiments, the second node <NUM> may receive information from, e.g., the first node <NUM>, the third node <NUM>, the fourth node <NUM>, the fifth node <NUM>, the sixth node <NUM>, and/or the seventh node <NUM>, through a receiving port <NUM>. In some examples, the receiving port <NUM> may be, for example, connected to one or more antennas in second node <NUM>. In other embodiments, the second node <NUM> may receive information from another structure in the system of communications networks <NUM> through the receiving port <NUM>. Since the receiving port <NUM> may be in communication with the processor <NUM>, the receiving port <NUM> may then send the received information to the processor <NUM>. The receiving port <NUM> may also be configured to receive other information.

The processor <NUM> in the second node <NUM> may be further configured to transmit or send information to e.g., the first node <NUM>, the third node <NUM>, the fourth node <NUM>, the fifth node <NUM>, the sixth node <NUM>, and/or the seventh node <NUM>, through a sending port <NUM>, which may be in communication with the processor <NUM>, and the memory <NUM>.

Those skilled in the art will also appreciate that the providing unit <NUM>, the receiving unit <NUM>, the obtaining unit <NUM>, the determining unit <NUM> and/or the registering unit <NUM> described above may refer to a combination of analog and digital circuits, and/or one or more processors configured with software and/or firmware, e.g., stored in memory, that, when executed by the one or more processors such as the processor <NUM>, perform as described above. One or more of these processors, as well as the other digital hardware, may be included in a single Application-Specific Integrated Circuit (ASIC), or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a System-on-a-Chip (SoC).

Any of the providing unit <NUM>, the receiving unit <NUM>, the obtaining unit <NUM>, the determining unit <NUM> and/or the registering unit <NUM> described above may be the processor <NUM> of the second node <NUM>, or an application running on such processor.

Thus, the methods according to the embodiments described herein for the second node <NUM> may be respectively implemented by means of a computer program <NUM> product, comprising instructions, i.e., software code portions, which, when executed on at least one processor <NUM>, cause the at least one processor <NUM> to carry out the actions described herein, as performed by the second node <NUM>. The computer program <NUM> product may be stored on a computer-readable storage medium <NUM>. The computer-readable storage medium <NUM>, having stored thereon the computer program <NUM>, may comprise instructions which, when executed on at least one processor <NUM>, cause the at least one processor <NUM> to carry out the actions described herein, as performed by the second node <NUM>. In some embodiments, the computer-readable storage medium <NUM> may be a non-transitory computer-readable storage medium, such as a CD ROM disc, a memory stick, or stored in the cloud space. In other embodiments, the computer program <NUM> product may be stored on a carrier containing the computer program, wherein the carrier is one of an electronic signal, optical signal, radio signal, or the computer-readable storage medium <NUM>, as described above.

The second node <NUM> may comprise an interface unit to facilitate communications between the second node <NUM> and other nodes or devices, e.g., the first node <NUM>, the third node <NUM>, the fourth node <NUM>, the fifth node <NUM>, the sixth node <NUM>, and/or the seventh node <NUM>. In some particular examples, the interface may, for example, include a transceiver configured to transmit and receive radio signals over an air interface in accordance with a suitable standard.

In other embodiments, the second node <NUM> may comprise the following arrangement depicted in <FIG>. The second node <NUM> may comprise a processing circuitry <NUM>, e.g., one or more processors such as the processor <NUM>, in the second node <NUM> and the memory <NUM>. The second node <NUM> may also comprise a radio circuitry <NUM>, which may comprise e.g., the receiving port <NUM> and the sending port <NUM>. The processing circuitry <NUM> may be configured to, or operable to, perform the method actions according to <FIG>, in a similar manner as that described in relation to <FIG>. The radio circuitry <NUM> may be configured to set up and maintain at least a wireless connection with the first node <NUM>, the third node <NUM>, the fourth node <NUM>, the fifth node <NUM>, the sixth node <NUM>, and/or the seventh node <NUM>. Circuitry may be understood herein as a hardware component.

Hence, embodiments herein also relate to the second node <NUM> operative to handle provision of an IMS service in the communications network <NUM>, the second node <NUM> being operative to operate in the communications network <NUM>. The communications network <NUM> is configured to comprise the first slice configured to handle the first IMS service, and the second slice configured to handle the second IMS service. The second node <NUM> may comprise the processing circuitry <NUM> and the memory <NUM>, said memory <NUM> containing instructions executable by said processing circuitry <NUM>, whereby the second node <NUM> is further operative to perform the actions described herein in relation to the second node <NUM>, e.g., in <FIG>.

<FIG> depicts two different examples in panels a) and b), respectively, of the arrangement that the seventh node <NUM>, <NUM>, <NUM> may comprise to perform the method actions described above in relation to <FIG>. In some embodiments, the seventh node <NUM>, <NUM>, <NUM> may comprise the following arrangement depicted in <FIG>. The seventh node <NUM>, <NUM>, <NUM> is configured to operate in the communications network <NUM>. The seventh node <NUM>, <NUM>, <NUM> is configured to handle provision of an IMS service in the communications network <NUM>. The seventh node <NUM>, <NUM>, <NUM> is configured to manage a terminating_ ICSCF, wherein the communications network <NUM> is configured to comprise the slice handling an IMS service.

Several embodiments are comprised herein. Components from one embodiment may be tacitly assumed to be present in another embodiment and it will be obvious to a person skilled in the art how those components may be used in the other exemplary embodiments. In <FIG>, optional boxes are indicated by dashed lines. The detailed description of some of the following corresponds to the same references provided above, in relation to the actions described for the seventh node <NUM>, <NUM>, <NUM>, and will thus not be repeated here. For example, in some embodiments the seventh node <NUM>, <NUM>, <NUM> may be configured to be one of the first terminating_ ICSCF and the second terminating_ ICSCF.

The seventh node <NUM>, <NUM>, <NUM> is configured to, e.g. by means of a registering unit <NUM> within the seventh node <NUM>, <NUM>, <NUM> configured to, register with the second node <NUM> as a provider of an IMS service. The second node <NUM> is configured to manage an NRF in the communications network <NUM>.

The seventh node <NUM>, <NUM>, <NUM> is also configured to, e.g. by means of a providing unit <NUM> within the seventh node <NUM>, <NUM>, <NUM> configured to, provide the IMS service based on the registration.

In some embodiments, to register may be configured to comprise one of: a) sending the first registration request from the seventh node <NUM> as a provider of a first IMS service, the first IMS service being configured to be VoLTE, and b) sending the second registration request from the seventh node <NUM> as a provider of a second IMS service, the second IMS service being configured to be RCS.

The embodiments herein may be implemented through one or more processors, such as a processor <NUM> in the seventh node <NUM>, <NUM>, <NUM> depicted in <FIG>, together with computer program code for performing the functions and actions of the embodiments herein. The program code mentioned above may also be provided as a computer program product, for instance in the form of a data carrier carrying computer program code for performing the embodiments herein when being loaded into the in the seventh node <NUM>, <NUM>, <NUM>. One such carrier may be in the form of a CD ROM disc. It is however feasible with other data carriers such as a memory stick. The computer program code may furthermore be provided as pure program code on a server and downloaded to the seventh node <NUM>, <NUM>, <NUM>.

The seventh node <NUM>, <NUM>, <NUM> may further comprise a memory <NUM> comprising one or more memory units. The memory <NUM> is arranged to be used to store obtained information, store data, configurations, schedulings, and applications etc. to perform the methods herein when being executed in the seventh node <NUM>, <NUM>, <NUM>.

In some embodiments, the seventh node <NUM>, <NUM>, <NUM> may receive information from, e.g., the first node <NUM>, the second node <NUM>, the third node <NUM>, the fourth node <NUM>, the fifth node <NUM>, and/or the sixth node <NUM> through a receiving port <NUM>. In some examples, the receiving port <NUM> may be, for example, connected to one or more antennas in seventh node <NUM>, <NUM>, <NUM>. In other embodiments, the seventh node <NUM>, <NUM>, <NUM> may receive information from another structure in the system of communications networks <NUM> through the receiving port <NUM>. Since the receiving port <NUM> may be in communication with the processor <NUM>, the receiving port <NUM> may then send the received information to the processor <NUM>. The receiving port <NUM> may also be configured to receive other information.

The processor <NUM> in the seventh node <NUM>, <NUM>, <NUM> may be further configured to transmit or send information to e.g., the first node <NUM>, the second node <NUM>, the third node <NUM>, the fourth node <NUM>, the fifth node <NUM>, and/or the sixth node <NUM>, through a sending port <NUM>, which may be in communication with the processor <NUM>, and the memory <NUM>.

Those skilled in the art will also appreciate that the registering unit <NUM>, and/or the providing unit <NUM> described above may refer to a combination of analog and digital circuits, and/or one or more processors configured with software and/or firmware, e.g., stored in memory, that, when executed by the one or more processors such as the processor <NUM>, perform as described above. One or more of these processors, as well as the other digital hardware, may be included in a single Application-Specific Integrated Circuit (ASIC), or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a System-on-a-Chip (SoC).

Any of the determining unit <NUM> and the registering unit <NUM>, and/or the providing unit <NUM> described above may be the processor <NUM> of the seventh node <NUM>, <NUM>, <NUM>, or an application running on such processor.

Thus, the methods according to the embodiments described herein for the seventh node <NUM>, <NUM>, <NUM> may be respectively implemented by means of a computer program <NUM> product, comprising instructions, i.e., software code portions, which, when executed on at least one processor <NUM>, cause the at least one processor <NUM> to carry out the actions described herein, as performed by the seventh node <NUM>, <NUM>, <NUM>. The computer program <NUM> product may be stored on a computer-readable storage medium <NUM>. The computer-readable storage medium <NUM>, having stored thereon the computer program <NUM>, may comprise instructions which, when executed on at least one processor <NUM>, cause the at least one processor <NUM> to carry out the actions described herein, as performed by the seventh node <NUM>, <NUM>, <NUM>. In some embodiments, the computer-readable storage medium <NUM> may be a non-transitory computer-readable storage medium, such as a CD ROM disc, a memory stick, or stored in the cloud space. In other embodiments, the computer program <NUM> product may be stored on a carrier containing the computer program, wherein the carrier is one of an electronic signal, optical signal, radio signal, or the computer-readable storage medium <NUM>, as described above.

The seventh node <NUM>, <NUM>, <NUM> may comprise an interface unit to facilitate communications between the seventh node <NUM>, <NUM>, <NUM> and other nodes or devices, e.g., the first node <NUM>, the second node <NUM>, the third node <NUM>, the fourth node <NUM>, the fifth node <NUM>, and/or the sixth node <NUM>. In some particular examples, the interface may, for example, include a transceiver configured to transmit and receive radio signals over an air interface in accordance with a suitable standard.

In other embodiments, the seventh node <NUM>, <NUM>, <NUM> may comprise the following arrangement depicted in <FIG>. The seventh node <NUM>, <NUM>, <NUM> may comprise a processing circuitry <NUM>, e.g., one or more processors such as the processor <NUM>, in the seventh node <NUM>, <NUM>, <NUM> and the memory <NUM>. The seventh node <NUM>, <NUM>, <NUM> may also comprise a radio circuitry <NUM>, which may comprise e.g., the receiving port <NUM> and the sending port <NUM>. The processing circuitry <NUM> may be configured to, or operable to, perform the method actions according to <FIG>, in a similar manner as that described in relation to <FIG>. The radio circuitry <NUM> may be configured to set up and maintain at least a wireless connection with the first node <NUM>, the second node <NUM>, the third node <NUM>, the fourth node <NUM>, the fifth node <NUM>, and/or the sixth node <NUM>. Circuitry may be understood herein as a hardware component.

Hence, embodiments herein also relate to the seventh node <NUM>, <NUM>, <NUM> operative to handle provision of an IMS service in the communications network <NUM>, the seventh node <NUM>, <NUM>, <NUM> being operative to operate in the communications network <NUM>. The seventh node <NUM>, <NUM>, <NUM> is operative to manage a terminating_ ICSCF, wherein the communications network <NUM> is operative to comprise a slice handling an IMS service. The seventh node <NUM>, <NUM>, <NUM> may comprise the processing circuitry <NUM> and the memory <NUM>, said memory <NUM> containing instructions executable by said processing circuitry <NUM>, whereby the seventh node <NUM>, <NUM>, <NUM> is further operative to perform the actions described herein in relation to the seventh node <NUM>, <NUM>, <NUM>, e.g., in <FIG>.

When using the word "comprise" or "comprising", it shall be interpreted as non limiting, i.e. meaning "consist at least of".

Therefore, the above embodiments should not be taken as limiting the scope of the invention.

As used herein, the expression "at least one of:" followed by a list of alternatives separated by commas, and wherein the last alternative is preceded by the "and" term, may be understood to mean that only one of the list of alternatives may apply, more than one of the list of alternatives may apply or all of the list of alternatives may apply. This expression may be understood to be equivalent to the expression "at least one of:" followed by a list of alternatives separated by commas, and wherein the last alternative is preceded by the "or" term.

As used herein, the expression "in some embodiments" has been used to indicate that the features of the embodiment described may be combined with any other embodiment or example disclosed herein.

Claim 1:
A method performed by a first node (<NUM>), the first node (<NUM>) operating in a communications network (<NUM>), the method being for handling provision of an Internet Protocol Multimedia Subsystem, IMS, service in the communications network (<NUM>), wherein the communications network (<NUM>) comprises a first slice handling a first IMS service, and a second slice handling a second IMS service, the method comprising:
obtaining (<NUM>), from a second node (<NUM>) operating in the communications network (<NUM>) and storing:
a) a first indication of a first routing service instance for a third node (<NUM>) comprised in the first slice, the third node (<NUM>) handling the first IMS service, and
b) a second indication of a second routing service instance for a fourth node (<NUM>) comprised in the second slice, the fourth node (<NUM>) handling the second IMS service, and
routing (<NUM>) a request, received from a fifth node (<NUM>) operating in another communications network (<NUM>), to one of the third node (<NUM>) and the fourth node (<NUM>), wherein:
i) with the proviso that the received request is for the first IMS service, the routing (<NUM>) is based on the obtained first indication, and
ii) with the proviso that the received request is for the second IMS service, the
routing (<NUM>) is based on the obtained second indication;
wherein the first node manages an Interconnection Border Control Function, IBCF, and the second node manages a Network Repository Function, NRF, the third node is a first terminating Interrogating-Call Session Control Function, I-CSCF, and the fourth node is a second terminating I-CSCF.