Patent Publication Number: US-2023156454-A1

Title: SUPPORT OF SHORT MESSAGE SERVICE OVER INTERNET PROTOCOL (SMSoIP) IN 5G-ONLY DEPLOYMENTS

Description:
TECHNICAL FIELD 
     The present disclosure relates to wireless communication and in particular, methods and apparatuses for short message service (SMS) delivery. 
     BACKGROUND 
     Currently, Third Generation Partnership Project (3GPP) Technical Specification (TS) 23.632 defines system procedures and services related to Home Subscriber Server/Home Location Register (HSS/HLR) and Unified Data Management (UDM) interworking in User Data Interworking Coexistence and Migration (UDICoM) for Mobile Terminated Short Message Service (MT SMS) delivery support. 
     However, system procedures to provide MT SMS delivery support are still lacking. 
     SUMMARY 
     Some embodiments advantageously provide methods and apparatuses for SMS delivery, such as support of SMS over Internet Protocol (SMSoIP) in Third Generation Partnership Project (3GPP) 5 th  Generation (5G, also called New Radio or NR)-only deployments. 
     In one embodiment, a method implemented in a data management (UDM) node includes receiving, from a home subscriber server (HSS) node, an address of an Internet Protocol-Short Message-Gateway (IP-SM-GW), the IP-SM-GW serving a user for a Short Message Service (SMS). 
     In one embodiment, a method implemented in a HSS node includes sending, to one of a unified data repository (UDR) node and a UDM node, an address of an IP-SM-GW, the IP-SM-GW serving a user for a SMS. 
     In one embodiment, a method implemented in a network node includes receiving, from an HSS node, an address of an IP-SM-GW, the IP-SM-GW serving a user for a SMS; and as a result of receiving a query from a UDM node for the address of the IP-SM-GW, sending the address of the IP-SM-GW to the UDM node. 
     According to an aspect of the present disclosure, method implemented in a unified data management, UDM, node, is provided. The method includes receiving, by the UDM node, a registration request from a home subscriber server, HSS, node, the registration request being to register an Internet Protocol-Short Message-Gateway, IP-SM-GW, and the registration request comprising an address of the IP-SM-GW. The method includes optionally, as a result of receiving the registration request comprising the address of the IP-SM-GW from the HSS node, determining message waiting data. 
     In some embodiments, the method further includes confirming the registration of the IP-SM-GW in a response message to the HSS node. In some embodiments, the method further includes storing the received address of the IP-SM-GW in a unified data repository, UDR, node as part of the registration of the IP-SM-GW. In some embodiments, the method further includes as a result of the registration of the IP-SM-GW and/or the received registration request comprising the address of the IP-SM-GW, one or more of: determining whether message waiting data are stored for a user associated with the IP-SM-GW; as a result of determining that the message waiting data are stored for the user, alerting at least one Short Message Service, SMS, service center, SC, and receiving a request for routing information from the at least one SMS SC; and using the address to communicate with the IP-SM-GW to provide a mobile terminated short message service, MT SMS, to a user equipment, UE, associated with the user. 
     In some embodiments, the method further includes one or more of: receiving, from the HSS node, a de-registration request to de-register the IP-SM-GW, the de-registration request comprising the address of the IP-SM-GW; and confirming a de-registration of the IP-SM-GW in a response message to the HSS node. In some embodiments, the method further includes removing the address of the IP-SM-GW from the UDR node as part of the de-registration of the IP-SM-GW. In some embodiments, one or more of: the HSS node comprises HSS functionality supporting Internet Protocol, IP, Multimedia Subsystem, IMS; and the HSS node lacks an HSS and/or Home Location Register, HLR, functionality supporting legacy access. 
     According to an aspect of the present disclosure, a method implemented in a home subscriber server, HSS, node is provided. The method includes receiving a registration request; and sending, to a unified data management, UDM, node, the registration request, the registration request being to register an Internet Protocol-Short Message-Gateway, IP-SM-GW, and the registration request comprising an address of the IP-SM-GW. In some embodiments, the method further includes receiving, from the UDM node, a confirmation of the registration of the IP-SM-GW in a response message. In some embodiments, the method further includes as a result of receiving a de-registration request, sending, to the UDM node, the de-registration request to de-register the IP-SM-GW, the de-registration request comprising the address of the IP-SM-GW; and receiving a confirmation of the de-registration of the IP-SM-GW in a response message. In some embodiments, one or more of: the HSS node comprises HSS functionality supporting Internet Protocol, IP, Multimedia Subsystem, IMS; and the HSS node lacks an HSS and/or Home Location Register, HLR, functionality supporting legacy access. 
     According to an aspect of the present disclosure, a method implemented in a system is provided. The system comprises a unified data management, UDM, node and a home subscriber server, HSS, node. The method comprises one or more of: the HSS node sending, to the UDM node, a registration request to register an Internet Protocol-Short Message-Gateway, IP-SM-GW, the registration request comprising an address of the IP-SM-GW; and the UDM node receiving, from the HSS node, the registration request comprising the address of the IP-SM-GW. 
     In some embodiments, the method further includes the UDM node storing the received address of the IP-SM-GW in a unified data repository, UDR, node as part of the registration of the IP-SM-GW. In some embodiments, the method further includes the UDM node confirming the registration of the IP-SM-GW in a response message to the HSS node. In some embodiments, the method further includes as a result of the registration of the IP-SM-GW and/or the received registration request comprising the address of the IP-SM-GW, one or more of: the UDM node determining whether message waiting data are stored for a user associated with the IP-SM-GW; the UDM node, as a result of determining that the message waiting data are stored for the user, alerting at least one Short Message Service, SMS, service center, SC, and receiving a request for routing information from the at least one SMS SC; and the UDM node using the address to communicate with the IP-SM-GW to provide a mobile terminated short message service, MT SMS, to a user equipment, UE, associated with the user. 
     In some embodiments, the method further includes the HSS node sending, to the UDM node, a de-registration request to de-register the IP-SM-GW, the de-registration request comprising the address of the IP-SM-GW; the UDM node receiving, from the HSS node, the de-registration request comprising the address of the IP-SM-GW; the UDM node confirming the de-registration of the IP-SM-GW in a response message to the HSS node; and the UDM node removing the address of the IP-SM-GW from a UDR node as part of the de-registration of the IP-SM-GW. In some embodiments, one or more of: the HSS node comprises HSS functionality supporting Internet Protocol, IP, Multimedia Subsystem, IMS; and the HSS node lacks an HSS and/or Home Location Register, HLR, functionality supporting legacy access. 
     According to an aspect of the present disclosure, a unified data management, UDM, node is provided. The UDM node comprises processing circuitry. The processing circuitry is configured to cause the UDM node to perform any one or more of the methods above. 
     According to an aspect of the present disclosure, a home subscriber server, HSS, node is provided. The HSS node comprises processing circuitry. The processing circuitry is configured to cause the HSS node to perform any one or more of the methods above. 
     According to an aspect of the present disclosure, a system is provided. The system comprises processing circuitry. The processing circuitry is configured to cause the system to perform any one or more of the methods above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of the present embodiments, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: 
         FIG.  1    illustrates an example system and scenario in which the IP-SM-GW address is unavailable to support MT SMS delivery; 
         FIG.  2    illustrates an example system architecture according to some embodiments of the present disclosure; 
         FIG.  3    illustrates yet another example system architecture and example hardware arrangements for devices in the system, according to some embodiments of the present disclosure; 
         FIG.  4    is a flowchart of an exemplary process in a UDM node according to some embodiments of the present disclosure; 
         FIG.  5    is a flowchart of an exemplary process in an HSS node according to some embodiments of the present disclosure; 
         FIG.  6    is a flowchart of an exemplary process in a network node (e.g., UDR node) according to some embodiments of the present disclosure; 
         FIG.  7    is a flowchart of an exemplary process in a UDM node according to some embodiments of the present disclosure; 
         FIG.  8    is a flowchart of an exemplary process in an HSS node according to some embodiments of the present disclosure; 
         FIG.  9    illustrates an example call flow diagram for the registration of the IP-SM-GW address in the UDM and subsequent SMS routing information retrieval according to some embodiments of the present disclosure; 
         FIG.  10    illustrates an example call flow diagram for the deregistration of the IP-SM-GW address in the UDM according to some embodiments of the present disclosure; 
         FIG.  11    illustrates an example call flow diagram for the retrieval of the IP-SM-GW address from the HSS (IMS) by the UDM upon reception of SMS routing information request according to some embodiments of the present disclosure; and 
         FIG.  12    illustrates an example call flow diagram for the registration (or deregistration) of the IP-SM-GW address in the 5GS-UDR and subsequent SMS routing information retrieval according to some embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     As described above, 3GPP TS 23.632 currently defines system procedures and services related to HSS/HLR and UDM interworking in UDICoM for MT SMS delivery support. 
     The scenarios considered assume that there is an HSS/HLR receiving requests from the Short Message Service-Gateway Mobile Switching Center (SMS-GMSC) over Mobile Application Part C (MAP C) and/or Diameter S6c reference points. These MAP C and Diameter S6c reference points with the SMS-GMSC are exposed by the HSS/HLR functionality supporting the Second Generation/Third Generation/Fourth Generation (2G/3G/4G) accesses as defined in, for example, 3GPP TS 23.040. 
     However, in the context of 3GPP Release 16 (Rel-16) UDICoM, for MT SMS delivery over Fifth Generation (5G, also called New Radio/NR) Non-Access-Stratum (NAS) in deployment scenarios where 2G/3G/4G accesses are not supported, the MAP C and Diameter S6c reference points with the SMS-GMSC are exposed by the UDM instead, since there may be no deployment of the HLR/HSS functionality supporting the legacy accesses and their corresponding reference points in the first place. 
     In these scenarios (e.g., MT SMS delivery over 5G NAS in deployment scenarios where 2G/3G/4G accesses are not supported), if support for SMSoIP is also expected, an HSS supporting Internet Protocol (IP) Multimedia Subsystem (IMS) functionality may be used including the support for the registration/de-registration of the IP-Short Message-Gateway (IP-SM-GW) address in the HSS over e.g., the Sh reference point as defined in, for example, 3GPP TS 23.204. 
     However, the HSS functionality supporting IMS does not expose the MAP C or Diameter S6c reference points with SMS-GMSC and neither the MAP J or Diameter S6c reference points with the IP-SM-GW. In the context of 3GPP Rel-16 UDICoM, in these cases, the MAP C/J and/or Diameter S6c reference points are exposed by the UDM instead. An example of these scenarios is depicted in an example system  10  in  FIG.  1   . 
     The system  10  includes an IP-SM-GW  12 , SMS-GMSC  14 , UDM  16 , HSS  18 , Proxy-Call Session Control Function (P-CSCF)  20 , UE  22  and Serving-Call Session Control Function (S-CSCF)  24 . 
     In some embodiments, the IP-SM-GW may be considered to provide an IMS application server which handles session initiation protocol (SIP) based messaging services for IMS subscribers. In addition, the IP-SM-GW may interact with the legacy short message service center (SMSC) using MAP signaling in order to allow IMS to SMS conversion and distribution. In some embodiments, the IP-SM-GW may be considered to implement transport layer interworking for SMS over IP. 
     As can be seen in  FIG.  1   , for MT SMS delivery, the UDM  16  may attempt to involve the IP-SM-GW  12 , but the IP-SM-GW address is not kept at the UDM  16  but at the HSS (IMS)  18  instead. The IP-SM-GW  12  will register in the HSS (IMS) while the SMS-GMSC  14  and IP-SM-GW  12  will interact with the UDM  16 . 
     In the context of 3GPP Rel-16 UDICoM, for MT SMS delivery over 5G NAS in deployment scenarios where 2G/3G/4G accesses are not supported and where support for SMS over IP is also expected, interactions between the UDM  16  and the HSS (IMS)  18  should be specified for e.g., the transfer of the IP-SM-GW address. Handling of the IP-SM-GW address in the interactions with Fifth Generation System UDR (5GS-UDR) via e.g., an Nudr interface should also be considered. 
     Some embodiments of the present disclosure provide for one or more new procedures to make the IP-SM-GW address available to the UDM in deployment scenarios where, for example, 2G/3G/4G accesses are not supported and support of SMS over IP is expected. 
     Some embodiments of the present disclosure may allow the UDM to identify and/or locate the IP-SM-GW that is serving a user for SMS. Some embodiments may provide proper support of MT SMS delivery procedures in 5G Core (5GC) only deployments where SMSoIP is required. 
     Before describing in detail exemplary embodiments, it is noted that the embodiments reside primarily in combinations of apparatus components and processing steps related to short message service (SMS) delivery. Accordingly, components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. 
     As used herein, relational terms, such as “first” and “second,” “top” and “bottom,” and the like, may be used solely to distinguish one entity or element from another entity or element without necessarily requiring or implying any physical or logical relationship or order between such entities or elements. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the concepts described herein. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     In embodiments described herein, the joining term, “in communication with” and the like, may be used to indicate electrical or data communication, which may be accomplished by physical contact, induction, electromagnetic radiation, radio signaling, infrared signaling or optical signaling, for example. One having ordinary skill in the art will appreciate that multiple components may interoperate and modifications and variations are possible of achieving the electrical and data communication. 
     In some embodiments described herein, the term “coupled,” “connected,” and the like, may be used herein to indicate a connection, although not necessarily directly, and may include wired and/or wireless connections. 
     In some embodiments, the non-limiting terms wireless device (WD) or a user equipment (UE) are used interchangeably. The UE herein can be any type of wireless device capable of communicating with a network node or another UE over radio signals. In some embodiments, the UE may be an autonomous machine configured to communicate via IMS. The UE herein can by any type of communication device capable of communicating with another UE, an application server, a network node, a server, an IMS NF or other IMS network node, via a wired connection and/or a wireless connection. The UE may also be a radio communication device, target device, device to device (D2D) UE, machine type UE or UE capable of machine to machine communication (M2M), low-cost and/or low-complexity UE, a sensor equipped with UE, Tablet, mobile terminals, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongles, Customer Premises Equipment (CPE), an Internet of Things (IoT) device, or a Narrowband IoT (NB-IOT) device etc. 
     In some embodiments, the term “node” is used herein and can be any kind of network node, such as, a subscriber server node (e.g., HSS) and/or a data management node (e.g., UDM). In some embodiments, the node may be, for example, a core network node, such as a 5G and/or NR network node, an IMS node, a Network Function (NF) node, such as, for example, a P-CSCF node, an S-CSCF node, an I-CSCF node, etc. 
     A node may include physical components, such as processors, allocated processing elements, or other computing hardware, computer memory, communication interfaces, and other supporting computing hardware. The node may use dedicated physical components, or the node may be allocated use of the physical components of another device, such as a computing device or resources of a datacenter, in which case the node is said to be virtualized. A node may be associated with multiple physical components that may be located either in one location, or may be distributed across multiple locations. 
     In some embodiments, the terms “gateway” and “IP-SM-GW” may be used interchangeably. In some embodiments, the terms “data management node” may be used interchangeably with “UDM node”. In some embodiments, the terms “subscriber node” and “HSS node” may be used interchangeably. In some embodiments, the terms “data repository node” and “UDR node” may be used interchangeably. 
     In some embodiments, the “address” herein may be considered an IP address or any other type of address or location identifier that may be used to identify and/or locate the IP-SM-GW for the user. 
     In some embodiments, the term “legacy access” may mean an HSS and/or HLR functionality supporting Evolved Packet Core (EPC) and/or circuit switched/packet switched (CS/PS) access technologies, respectively. Any two or more embodiments described in this disclosure may be combined in any way with each other. 
     Note also that some embodiments of the present disclosure may be supported by standard documents disclosed in Third Generation Partnership Project (3GPP) technical specifications. That is, some embodiments of the description can be supported by the above documents. In addition, all the terms disclosed in the present document may be described by the above standard documents. 
     Note that although terminology from one particular wireless system, such as, for example, 3 rd  Generation Partnership Project (3GPP), Long Term Evolution (LTE), 5 th  Generation (5G) (also known as New Radio (NR)), may be used in this disclosure, this should not be seen as limiting the scope of the disclosure to only the aforementioned system. Other wireless systems, including without limitation Wide Band Code Division Multiple Access (WCDMA), Worldwide Interoperability for Microwave Access (WiMax), Ultra Mobile Broadband (UMB) and Global System for Mobile Communications (GSM), may also benefit from exploiting the ideas covered within this disclosure. 
     Note further, that functions described herein as being performed by a UE or a UDM node or an HSS node or any network node may be distributed over a plurality of UEs or a plurality of UDM nodes or a plurality of HSS nodes or a plurality of network nodes. In other words, it is contemplated that the functions of the UE, UDM node, HSS node or network node described herein are not limited to performance by a single physical device and, in fact, can be distributed among several physical devices. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     Referring again to the drawing figures, in which like elements are referred to by like reference numerals, there is shown in  FIG.  2    a schematic diagram of a communication system  10 , according to an embodiment, constructed in accordance with the principles of the present disclosure. The communication system  10  in  FIG.  2    is a non-limiting example and other embodiments of the present disclosure may be implemented by one or more other systems and/or networks. Referring to  FIG.  2   , the system  10  includes a UDM  26  and HSS  28  that may be configured according to one or more of the embodiments of the present disclosure. In addition, the system  10  includes the IP-SM-GW  12 , SMS-GMSC  14 , UE  22  and an IMS core including a P-CSCF  20  and a S-CSCF  24 . 
     The system  10  may include UDM  26  configured to include messenger  30  which is configured to cause UDM  26  to receive a registration request from a home subscriber server, HSS, node, the registration request being to register an Internet Protocol-Short Message-Gateway, IP-SM-GW, and the registration request comprising an address of the IP-SM-GW; and optionally, as a result of receiving the registration request comprising the address of the IP-SM-GW from the HSS node, determine message waiting data. The system  10  includes HSS  28  configured to include addresser  32  which is configured to cause HSS  28  to receive a registration request; and send, to a unified data management, UDM, node, the registration request, the registration request being to register an Internet Protocol-Short Message-Gateway, IP-SM-GW, and the registration request comprising an address of the IP-SM-GW. The system  10  includes querier  34  which is configured to query a unified data repository (UDR) node for the address of the IP-SM-GW. 
     It should be noted that, for simplicity, a single node is shown for the various entities in the system  10  depicted in  FIG.  2    (e.g., a single UE  22 , a single IP-SM-GW  12 , a single IMS core, a single UDM  26 , a single HSS  28 , etc.). It should be understood that the system  10  may include numerous entities/nodes of those shown in  FIG.  2   , as well as, additional entities/nodes not shown in  FIG.  2   . In addition, the system  10  may include many more connections/interfaces than those shown in  FIG.  2   . 
     Example implementations, in accordance with an embodiment, of the UE  22 , UDM node  26 , HSS node  28  and a network node  36  (e.g., Unified Data Repository (UDR) or any other node) discussed herein will now be described with reference to  FIG.  3   . It is noted that, the interconnection of the UE  22 , UDM node  26 , HSS node  28  and network node  36  are shown in serial, such depiction is for the sake of simplicity and ease of explanation. It is understood that or more of the UE  22 , UDM node  26 , HSS node  28  and the network node  36  may communicate via a wired and/or wireless network, i.e., cloud network, and that the UE  22 , UDM node  26 , HSS node  28  and the network node  36  are not literally connected to one another. In other words, in  FIG.  3   , the connection between the devices UE  22 , UDM node  26 , HSS node  28  and network node  36  (e.g., UDR) is shown without explicit reference to any intermediary devices or connections. However, it should be understood that intermediary devices and/or connections may exist between these devices, although not explicitly shown. 
     The UE  22  includes a communication interface  38 , processing circuitry  40 , and memory  42 . The communication interface  38  may be configured to communicate with any other elements/nodes in the system  10  according to the techniques in the present disclosure. In some embodiments, the communication interface  38  may be formed as or may include, for example, one or more radio frequency (RF) transmitters, one or more RF receivers, and/or one or more RF transceivers, and/or may be considered a radio interface. In some embodiments, the communication interface  38  may include a wired interface. 
     The processing circuitry  40  may include one or more processors  44  and memory, such as, the memory  42 . In particular, in addition to a traditional processor and memory, the processing circuitry  40  may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor  44  may be configured to access (e.g., write to and/or read from) the memory  42 , which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory). 
     Thus, the UE  22  may further include software stored internally in, for example, memory  42 , or stored in external memory (e.g., database) accessible by the UE  22  via an external connection. The software may be executable by the processing circuitry  40 . The processing circuitry  40  may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by the UE  22 . The memory  42  is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software may include instructions stored in memory  42  that, when executed by the processor  44  causes the processing circuitry  40  and/or configures the UE  22  to perform the processes described herein with respect to the UE  22 . 
     The UDM node  26  includes a communication interface  46 , processing circuitry  48 , and memory  50 . The communication interface  46  may be configured to communicate with any other elements/nodes in the system  10  according to the techniques in the present disclosure. In some embodiments, the communication interface  46  may be formed as or may include, for example, one or more radio frequency (RF) transmitters, one or more RF receivers, and/or one or more RF transceivers, and/or may be considered a radio interface. In some embodiments, the communication interface  46  may include a wired interface. 
     The processing circuitry  48  may include one or more processors  52  and memory, such as, the memory  50 . In particular, in addition to a traditional processor and memory, the processing circuitry  48  may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor  52  may be configured to access (e.g., write to and/or read from) the memory  50 , which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory). 
     Thus, the UDM node  26  may further include software stored internally in, for example, memory  50 , or stored in external memory (e.g., database) accessible by the UDM node  26  via an external connection. The software may be executable by the processing circuitry  48 . The processing circuitry  48  may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by the UDM node  26 . The memory  50  is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software may include instructions stored in memory  50  that, when executed by the processor  52  and/or messenger  30 , causes the processing circuitry  48  and/or configures the UDM node  26  to perform the processes described herein with respect to the UDM node  26  (e.g., processes described with reference to  FIG.  4    and/or any of the other flowcharts). 
     The HSS node  28  includes a communication interface  54 , processing circuitry  56 , and memory  58 . The communication interface  54  may be configured to communicate with any other elements/nodes in the system  10  according to the techniques in the present disclosure. In some embodiments, the communication interface  54  may be formed as or may include, for example, one or more radio frequency (RF) transmitters, one or more RF receivers, and/or one or more RF transceivers, and/or may be considered a radio interface. In some embodiments, the communication interface  54  may include a wired interface. 
     The processing circuitry  56  may include one or more processors  60  and memory, such as, the memory  58 . In particular, in addition to a traditional processor and memory, the processing circuitry  56  may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor  60  may be configured to access (e.g., write to and/or read from) the memory  58 , which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory). 
     Thus, the HSS node  28  may further include software stored internally in, for example, memory  58 , or stored in external memory (e.g., database) accessible by the HSS node  28  via an external connection. The software may be executable by the processing circuitry  56 . The processing circuitry  56  may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by the HSS node  28 . The memory  58  is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software may include instructions stored in memory  58  that, when executed by the processor  60  and/or addresser  32 , causes the processing circuitry  56  and/or configures the HSS node  28  to perform the processes described herein with respect to the HSS node  28  (e.g., processes described with reference to  FIG.  5    and/or any of the other flowcharts). 
     The network node  36  (e.g., UDR node, IP-SM-GW, etc.) includes a communication interface  62 , processing circuitry  64 , and memory  66 . The communication interface  62  may be configured to communicate with any other elements/nodes in the system  10  according to the techniques in the present disclosure. In some embodiments, the communication interface  62  may be formed as or may include, for example, one or more radio frequency (RF) transmitters, one or more RF receivers, and/or one or more RF transceivers, and/or may be considered a radio interface. In some embodiments, the communication interface  62  may include a wired interface. 
     The processing circuitry  64  may include one or more processors  68  and memory, such as, the memory  66 . In particular, in addition to a traditional processor and memory, the processing circuitry  64  may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor  68  may be configured to access (e.g., write to and/or read from) the memory  66 , which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory). 
     Thus, the network node  36  may further include software stored internally in, for example, memory  66 , or stored in external memory (e.g., database) accessible by the network node  36  via an external connection. The software may be executable by the processing circuitry  64 . The processing circuitry  64  may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by the network node  36 . The memory  66  is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software may include instructions stored in memory  66  that, when executed by the processor  68  and/or querier  34 , causes the processing circuitry  64  and/or configures the network node  36  to perform the processes described herein with respect to the network node  36  (e.g., 5GS-UDR node, IP-SM-GW, etc.) such as the processes described with reference to  FIG.  6    as well as other figures. 
     Although  FIG.  3    shows messenger  30 , addresser  32 , querier  34  as being within a respective processor, it is contemplated that these elements may be implemented such that a portion of the elements is stored in a corresponding memory within the processing circuitry. In other words, the elements may be implemented in hardware or in a combination of hardware and software within the processing circuitry. 
       FIG.  4    is a flowchart of an exemplary process in a UDM node  26  for supporting delivery of an SMS message to the UE  22  according to one or more of the techniques in the present disclosure. One or more Blocks and/or functions and/or methods performed by the UDM node  26  may be performed by one or more elements of UDM node  26  such as by messenger  30  in processing circuitry  48 , memory  50 , processor  52 , communication interface  46 , etc. according to the example process/method. The example process includes receiving (Block S 100 ), such as via messenger  30 , processing circuitry  48 , memory  50 , processor  52  and/or communication interface  46 , from a home subscriber server (HSS) node  28 , an address of an Internet Protocol-Short Message-Gateway (IP-SM-GW)  12 , the IP-SM-GW  12  serving a user for a Short Message Service (SMS). 
     In some embodiments, receiving the address of the IP-SM-GW from the HSS node includes receiving, such as via messenger  30 , processing circuitry  48 , memory  50 , processor  52  and/or communication interface  46 , a registration request to register the IP-SM-GW in a unified data management (UDM) node, the registration request including the address of the IP-SM-GW associated with the user. 
     In some embodiments, the method further includes at least one of: receiving, such as via messenger  30 , processing circuitry  48 , memory  50 , processor  52  and/or communication interface  46 , a de-registration request to de-register the IP-SM-GW, the de-registration request including the address of the IP-SM-GW; and confirming, such as via messenger  30 , processing circuitry  48 , memory  50 , processor  52  and/or communication interface  46 , one of the registration and the de-registration of the IP-SM-GW in a response message. 
     In some embodiments, the method includes one or more of, such as via messenger  30 , processing circuitry  48 , memory  50 , processor  52  and/or communication interface  46 : storing the address in a unified data repository (UDR) node as part of the registration of the IP-SM-GW; removing the address in the UDR node as part of the registration of the IP-SM-GW; determining whether message waiting data are stored for the user associated with the IP-SM-GW; and/or using the address to communicate with the IP-SM-GW to provide a mobile terminated short message service (MT SMS) to a user equipment (UE) associated with the user. 
     In some embodiments, receiving the address of the IP-SM-GW from the HSS node includes determining, such as via messenger  30 , processing circuitry  48 , memory  50 , processor  52  and/or communication interface  46 , whether the address is available in a home subscriber server (HSS) node by sending a request to the HSS node; and as a result of the request, receiving, such as via messenger  30 , processing circuitry  48 , memory  50 , processor  52  and/or communication interface  46 , a response from the HSS node, the response including the address of the IP-SM-GW associated with the user. 
     In some embodiments, receiving the address of the IP-SM-GW from the HSS node includes querying, such as via messenger  30 , processing circuitry  48 , memory  50 , processor  52  and/or communication interface  46 , a unified data repository (UDR) node for the address of the IP-SM-GW; and responsive to the query, receiving, such as via messenger  30 , processing circuitry  48 , memory  50 , processor  52  and/or communication interface  46 , the address from the UDR node. 
       FIG.  5    is a flowchart of an exemplary process in an HSS node  28  for supporting delivery of an SMS message to the UE  22  according to one or more of the techniques in the present disclosure. One or more Blocks and/or functions and/or methods performed by the HSS node  28  may be performed by one or more elements of HSS node  28  such as via addresser  32  in processing circuitry  56 , memory  58 , processor  60 , communication interface  54 , etc. according to the example process/method. The example process includes sending (Block S 102 ), such as via addresser  32 , processing circuitry  56 , memory  58 , processor  60  and/or communication interface  54 , to one of a unified data repository (UDR) node and a unified data management (UDM) node, an address of an Internet Protocol-Short Message-Gateway (IP-SM-GW), the IP-SM-GW serving a user for a Short Message Service (SMS). 
     In some embodiments, sending, to the UDM node, the address of the IP-SM-GW includes sending, such as via addresser  32 , processing circuitry  56 , memory  58 , processor  60  and/or communication interface  54 , a registration request to register the IP-SM-GW, the registration request including the address of the IP-SM-GW associated with the user. In some embodiments, the method further includes at least one of: sending, such as via addresser  32 , processing circuitry  56 , memory  58 , processor  60  and/or communication interface  54 , a de-registration request to de-register the IP-SM-GW, the de-registration request including the address of the IP-SM-GW; and receiving, such as via addresser  32 , processing circuitry  56 , memory  58 , processor  60  and/or communication interface  54 , a confirmation of one of the registration and the de-registration of the IP-SM-GW in a response message. 
     In some embodiments, sending, to the UDM node, the address of the IP-SM-GW is responsive to the HSS node  28 : receiving, such as via addresser  32 , processing circuitry  56 , memory  58 , processor  60  and/or communication interface  54 , a request for the address from the UDM node; and responsive to the request, sending, such as via addresser  32 , processing circuitry  56 , memory  58 , processor  60  and/or communication interface  54 , a response to the UDM node, the response including the address of the IP-SM-GW associated with the user. In some embodiments, sending the address of the IP-SM-GW includes sending the address of the IP-SM-GW to the UDR node. 
       FIG.  6    is a flowchart of an exemplary process in a network node  36  (e.g., UDR node) for supporting delivery of an SMS message to the UE  22  according to one or more of the techniques in the present disclosure. One or more Blocks and/or functions and/or methods performed by the network node  36  may be performed by one or more elements of network node  36  such as via querier  34  in processing circuitry  64 , memory  66 , processor  68 , communication interface  62 , etc. according to the example process/method. The example process includes receiving (Block S 104 ), such as via querier  34 , processing circuitry  64 , memory  66 , processor  68  and/or communication interface  62 , from a home subscriber server (HSS) node, an address of an Internet Protocol-Short Message-Gateway (IP-SM-GW), the IP-SM-GW serving a user for a Short Message Service (SMS). The process includes as a result of receiving a query from a unified data management (UDM) node for the address of the IP-SM-GW, sending (Block S 106 ), such as via querier  34 , processing circuitry  64 , memory  66 , processor  68  and/or communication interface  62 , the address of the IP-SM-GW to the UDM node. In some embodiments, the network node  36  is a unified data repository (UDR) node. 
       FIG.  7    is a flowchart of an exemplary process in a UDM node  26  for supporting delivery of an SMS message to the UE  22  according to one or more of the techniques in the present disclosure. One or more Blocks and/or functions and/or methods performed by the UDM node  26  may be performed by one or more elements of UDM node  26  such as by messenger  30  in processing circuitry  48 , memory  50 , processor  52 , communication interface  46 , etc. according to the example process/method. The example process includes receiving (Block S 108 ) by the UDM node, such as by messenger  30 , processing circuitry  48 , memory  50 , processor  52  and/or communication interface  46 , a registration request from a home subscriber server, HSS, node, the registration request being to register an Internet Protocol-Short Message-Gateway, IP-SM-GW, and the registration request comprising an address of the IP-SM-GW. The method includes optionally, as a result of receiving the registration request comprising the address of the IP-SM-GW from the HSS node, determining (Block S 110 ), such as by messenger  30 , processing circuitry  48 , memory  50 , processor  52  and/or communication interface  46 , message waiting data. 
     In some embodiments, the method includes confirming, such as by messenger  30 , processing circuitry  48 , memory  50 , processor  52  and/or communication interface  46 , the registration of the IP-SM-GW in a response message to the HSS node. In some embodiments, the method includes storing, such as by messenger  30 , processing circuitry  48 , memory  50 , processor  52  and/or communication interface  46 , the received address of the IP-SM-GW in a unified data repository, UDR, node as part of the registration of the IP-SM-GW. In some embodiments, the method includes as a result of the registration of the IP-SM-GW and/or the received registration request comprising the address of the IP-SM-GW, one or more of: determining, such as by messenger  30 , processing circuitry  48 , memory  50 , processor  52  and/or communication interface  46 , whether message waiting data are stored for a user associated with the IP-SM-GW; as a result of determining that the message waiting data are stored for the user, alerting, such as by messenger  30 , processing circuitry  48 , memory  50 , processor  52  and/or communication interface  46 , at least one Short Message Service, SMS, service center, SC, and receiving a request for routing information from the at least one SMS SC; and using, such as by messenger  30 , processing circuitry  48 , memory  50 , processor  52  and/or communication interface  46 , the address to communicate with the IP-SM-GW to provide a mobile terminated short message service, MT SMS, to a user equipment, UE, associated with the user. 
     In some embodiments, the method includes one or more of: receiving, such as by messenger  30 , processing circuitry  48 , memory  50 , processor  52  and/or communication interface  46 , from the HSS node, a de-registration request to de-register the IP-SM-GW, the de-registration request comprising the address of the IP-SM-GW; and confirming, such as by messenger  30 , processing circuitry  48 , memory  50 , processor  52  and/or communication interface  46 , a de-registration of the IP-SM-GW in a response message to the HSS node. In some embodiments, the method includes removing, such as by messenger  30 , processing circuitry  48 , memory  50 , processor  52  and/or communication interface  46 , the address of the IP-SM-GW from the UDR node as part of the de-registration of the IP-SM-GW. In some embodiments, one or more of: the HSS node comprises HSS functionality supporting Internet Protocol, IP, Multimedia Subsystem, IMS; and the HSS node lacks an HSS and/or Home Location Register, HLR, functionality supporting legacy access. 
       FIG.  8    is a flowchart of an exemplary process in an HSS node  28  for supporting delivery of an SMS message to the UE  22  according to one or more of the techniques in the present disclosure. One or more Blocks and/or functions and/or methods performed by the HSS node  28  may be performed by one or more elements of HSS node  28  such as via addresser  32  in processing circuitry  56 , memory  58 , processor  60 , communication interface  54 , etc. according to the example process/method. The example process includes receiving (Block S 112 ), such as via addresser  32 , processing circuitry  56 , memory  58 , processor  60  and/or communication interface  54 , a registration request. The method includes sending (Block S 114 ), such as via addresser  32 , processing circuitry  56 , memory  58 , processor  60  and/or communication interface  54 , to a unified data management, UDM, node, the registration request, the registration request being to register an Internet Protocol-Short Message-Gateway, IP-SM-GW, and the registration request comprising an address of the IP-SM-GW. 
     In some embodiments, the method further includes receiving, such as via addresser  32 , processing circuitry  56 , memory  58 , processor  60  and/or communication interface  54 , from the UDM node, a confirmation of the registration of the IP-SM-GW in a response message. In some embodiments, the method further includes as a result of receiving a de-registration request, sending, such as via addresser  32 , processing circuitry  56 , memory  58 , processor  60  and/or communication interface  54 , to the UDM node, the de-registration request to de-register the IP-SM-GW, the de-registration request comprising the address of the IP-SM-GW; and receiving, such as via addresser  32 , processing circuitry  56 , memory  58 , processor  60  and/or communication interface  54 , a confirmation of the de-registration of the IP-SM-GW in a response message. In some embodiments, one or more of: the HSS node comprises HSS functionality supporting Internet Protocol, IP, Multimedia Subsystem, IMS; and the HSS node lacks an HSS and/or Home Location Register, HLR, functionality supporting legacy access. 
     Having generally described arrangements for supporting short message service (SMS) delivery in certain scenarios, a more detailed description of some of the embodiments are provided as follows with reference to  FIGS.  9 - 12   , and which may be implemented by UE  22 , UDM node  26 , HSS node  28  and/or any network node (e.g., network node  36 , UDR node, etc.) discussed herein. 
     Some embodiments of the present disclosure provide a new procedure to make the IP-SM-GW address available to the UDM node  26  in deployment scenarios where 2G/3G/4G accesses are not supported and support of SMS over IP is expected to be provided. Some example embodiments and/or alternatives to define the interactions that allow the UDM node  26  to obtain the IP-SM-GW address are described below with reference to the call flow diagrams in  FIGS.  9 - 12   , in which at least some notable steps are bolded below for clarity. 
     Embodiment 1: IP-SM-GW Registration in UDM 
       FIG.  9    shows an example call flow diagram for the registration of the IP-SM-GW address in the UDM node  26  and subsequent SMS routing information retrieval, as shown in the following call flow diagram steps: 
     S 116 . The IP-SM-GW  12  registers its address in an HSS node  28  (IMS) via the Sh interface as defined in e.g., 3GPP TS 23.204. If the Evolved Packet System UDR (EPS-UDR network node  36 ) is used, the HSS node  28  (IMS) stores the IP-SM-GW&#39;s  12  address in the EPS-UDR network node  36 . 
     S 118 . The HSS node  28  forwards the IP-SM-GW&#39;s  12  registration to the UDM node  26  using e.g., a Nudm_UECM_IPSMGWRegistration request. The request includes the address of the IP-SM-GW  12  to be registered in the UDM node  26 . 
     S 120 . If the 5GS-UDR is used, the UDM node  26  stores the IP-SM-GW&#39;s  12  address in the 5GS-UDR using the Nudr_DM_Update service operation. 
     S 122 . The UDM node  26  confirms the IP-SM-GW&#39;s  12  registration with a successful Nudm_UECM_IPSMGWRegistration response. 
     After successful registration of the IP-SM-GW&#39;s  12  address, the UDM node  26  determines whether message waiting data are stored and alerts all Service Centres using procedures described in, for example, 3GPP TS 23.204 if applicable. 
     S 124 -S 136 . The UDM node  26  receives a request for routing information from the SMS-GMSC  14  via MAP or Diameter. If the 5GS-UDR is used, the UDM node  26  queries the 5GS-UDR to read the registered Short Message Service Function (SMSF) and/or IP-SM-GW  12 , if any. Routing information is provided to SMS-GMSC  14  from IP-SM-GW  12  or UDM node  26 . 
     The options  5   a - 5   f,  i.e., steps S 124 -S 136  shown in  FIG.  9    are based on the options for MT SMS procedure described in section 6.4 of 3GPP TS 23.204, considering a 5GC only deployment where the UDM node  26  is present and HLR/HSS serving 2G/3G/4G accesses are not deployed. Steps  5   a - 5   c  correspond to  3   a - 3   c;  step  5   d  corresponds to  3   d;  and steps  5   e - 5   f  correspond to  3   e - 3   f,  respectively, as shown in  FIG.  6 . 4    of 3GPP TS 23.204. 
       FIG.  10    shows an example call flow diagram for the deregistration of the IP-SM-GW  12  address in the UDM node  26 , as shown in the following call flow diagram steps: 
     S 138 . The IP-SM-GW  12  deregisters its address in the HSS node  28  (IMS) via Sh as defined in, for example, 3GPP TS 23.204. If the EPS-UDR network node  36  is used, the HSS node  28  (IMS) removes the IP-SM-GW&#39;s  12  address from the EPS-UDR network node  36 . 
     S 140 . The HSS node  28  forwards the IP-SM-GW&#39;s  12  deregistration request to the UDM node  26  using a Nudm_UECM_IPSMGWDeregistration request. 
     S 142 . If the 5GS-UDR is used, the UDM node  26  removes the IP-SM-GW&#39;s  12  address from the 5GS-UDR using the Nudr_DM_Update service operation. 
     S 144 . The UDM node  26  confirms the IP-SM-GW&#39;s  12  deregistration with a successful Nudm_UECM_IPSMGWDeregistration response. 
     S 146 -S 148 . If the UDM node  26  receives a request for routing information from the SMS-GMSC via MAP or Diameter, the UDM node  26  determines if there is an IP-SM-GW  12  address registered for the UE  22 . If the 5GS-UDR is used, the UDM node  26  queries the 5GS-UDR to read the registered SMSF and/or IP-SM-GW  12 , if any. If an IP-SM-GW  12  address is not present, the UDM node  26  may follow the MT SMS procedures defined in section 4.13.3 of 3GPP TS 23.502 and 3GPP TS 23.040. 
     Embodiment 2: IP-SM-GW Address Retrieval by UDM 
     In addition, or alternatively, in some embodiments, when the UDM node  26  receives a request for routing information from the SMS-GMSC  14  via MAP or Diameter, the UDM node  26  may determine in the HSS node  28  (IMS) if there is an IP-SM-GW  12  address. 
       FIG.  11    shows an example call flow diagram for the retrieval of the IP-SM-GW  12  address from the HSS node  28  (IMS) by the UDM node  26  upon reception of an SMS routing information request, as shown in the following call flow diagram steps: 
     S 150 . The IP-SM-GW  12  registers its address in HSS node  28  (IMS) via the Sh interface as defined in 3GPP TS 23.204. If the EPS-UDR network node  36  is used, the HSS node  28  (IMS) stores the IP-SM-GW  12  address in the EPS-UDR network node  36 . 
     S 152 . At any time, the UDM node  26  may receive a request for routing information from the SMS-GMSC  14  via MAP or Diameter. 
     S 154 . The UDM node  26  determines whether the IP-SM-GW  12  address is available in the HSS node  28  (IMS) using the Nhss_ImsSDM_Get service operation (e.g., sending a Nhss_ImsSDM_Get Request( ) to HSS node  28 ). 
     S 156 . The HSS node  28  (IMS) provides in the Nhss_ImsSDM_Get response to the UDM node  26  the IP-SM-GW  12  address registered for the user. 
     S 158 -S 164 . SMS routing information including the IP-SM-GW&#39;s  12  address is provided to SMS-GMSC  14  as described in e.g., section 6.4 of 3GPP TS 23.204, considering a 5GC only deployment where UDM node  26  is present and HLR/HSS serving 2G/3G/4G accesses is not deployed. 
     Embodiment 3: IP-SM-GW Registration and Deregistration in 5GS-UDR 
     Additionally, and/or alternatively, the registration and deregistration of the IP-SM-GW  12  address in the UDM node  26  may be performed by direct interaction from the HSS node  28  (IMS) to 5GS-UDR (e.g., network node  36   b ). 
       FIG.  12    shows an example call flow diagram for the registration (or deregistration) of the IP-SM-GW  12  address in the 5GS-UDR (e.g., network node  36   b ) and subsequent SMS routing information retrieval, as shown in the following call flow diagram steps: 
     S 166 . The IP-SM-GW  12  registers or deregisters its address in HSS node  28  (IMS) via Sh as defined in TS 23.204. 
     S 168 . If the EPS-UDR (e.g., network node  36   a ) is used, the HSS node  28  (IMS) stores (e.g., UD Write for registration) or removes (e.g., for deregistration) the IP-SM-GW  12  address in the EPS-UDR (e.g., network node  36   a ). 
     S 170 . The HSS node  28  (IMS) also stores (e.g., Nudr_DM_Update( ) for registration) or removes (e.g., for deregistration) the IP-SM-GW  12  address in the 5GS-UDR (e.g., network node  36   b ) using the Nudr_DM_Update service operation. 
     S 172 . The UDM node  26  receives a request for routing information from the SMS-GMSC  14  via MAP or Diameter. 
     S 174 . The UDM node  26  determines whether an IP-SM-GW  12  address is available in the 5GS-UDR (e.g., network node  36   b ) using the Nudr_DM_Query service operation. 
     S 176 -S 182 . SMS routing information including IP-SM-GW  12  address is provided to SMS-GMSC as described in section 6.4 of 3GPP TS 23.204, considering a 5GC only deployment where UDM node  26  is present and HLR/HSS serving 2G/3G/4G accesses is not deployed. 
     Some embodiments may include one or more of the following: 
     Embodiment A1. A method implemented in a data management (UDM) node, the method comprising: 
     receiving, from a home subscriber server (HSS) node, an address of an Internet Protocol-Short Message-Gateway (IP-SM-GW), the IP-SM-GW serving a user for a Short Message Service (SMS). 
     Embodiment A2. The method of Embodiment A1, wherein receiving the address of the IP-SM-GW from the HSS node includes: 
     receiving a registration request to register the IP-SM-GW in a unified data management (UDM) node, the registration request including the address of the IP-SM-GW associated with the user. 
     Embodiment A3. The method of Embodiment A2, further comprising at least one of: 
     receiving a de-registration request to de-register the IP-SM-GW, the de-registration request including the address of the IP-SM-GW; and 
     confirming one of the registration and the de-registration of the IP-SM-GW in a response message. 
     Embodiment A4. The method of any one of Embodiments A2 and A3, further comprising one or more of: 
     storing the address in a unified data repository (UDR) node as part of the registration of the IP-SM-GW; 
     removing the address in the UDR node as part of the deregistration of the IP-SM-GW; 
     determining whether message waiting data are stored for the user associated with the IP-SM-GW; and/or 
     using the address to communicate with the IP-SM-GW to provide a mobile terminated short message service (MT SMS) to a user equipment (UE) associated with the user. 
     Embodiment A5. The method of Embodiment A1, wherein receiving the address of the IP-SM-GW from the HSS node includes: 
     determining whether the address is available in a home subscriber server (HSS) node by sending a request to the HSS node; and 
     as a result of the request, receiving a response from the HSS node, the response including the address of the IP-SM-GW associated with the user. 
     Embodiment A6. The method of Embodiment A1, wherein receiving the address of the IP-SM-GW from the HSS node includes: 
     querying a unified data repository (UDR) node for the address of the IP-SM-GW; and 
     responsive to the query, receiving the address from the UDR node. 
     Embodiment B1. A method implemented in a home subscriber server (HSS) node, the method comprising: 
     sending, to one of a unified data repository (UDR) node and a unified data management (UDM) node, an address of an Internet Protocol-Short Message-Gateway (IP-SM-GW), the IP-SM-GW serving a user for a Short Message Service (SMS). 
     Embodiment B2. The method of Embodiment B1, wherein sending, to the UDM node, the address of the IP-SM-GW includes: 
     sending a registration request to register the IP-SM-GW, the registration request including the address of the IP-SM-GW associated with the user. 
     Embodiment B3. The method of Embodiment B2, further comprising at least one of: 
     sending a de-registration request to de-register the IP-SM-GW, the de-registration request including the address of the IP-SM-GW; and 
     receiving a confirmation of one of the registration and the de-registration of the IP-SM-GW in a response message. 
     Embodiment B4. The method of Embodiment B1, wherein sending, to the UDM node, the address of the IP-SM-GW is responsive to the HSS node: 
     receiving a request for the address from the UDM node; and 
     responsive to the request, sending a response to the UDM node, the response including the address of the IP-SM-GW associated with the user. 
     Embodiment B5. The method of Embodiment B1, wherein sending the address of the IP-SM-GW includes: 
     sending the address of the IP-SM-GW to the UDR node. 
     Embodiment C1. A method implemented in a network node, the method comprising: 
     receiving, from a home subscriber server (HSS) node, an address of an Internet Protocol-Short Message-Gateway (IP-SM-GW), the IP-SM-GW serving a user for a Short Message Service (SMS); and 
     as a result of receiving a query from a unified data management (UDM) node for the address of the IP-SM-GW, sending the address of the IP-SM-GW to the UDM node. 
     Embodiment C2. The method of Embodiment C1, wherein the network node is a unified data repository (UDR) node. 
     Embodiment D1. A data management (UDM) node, the UDM node comprising processing circuitry, the processing circuitry configured to cause the UDM node to: 
     receive, from a home subscriber server (HSS) node, an address of an Internet Protocol-Short Message-Gateway (IP-SM-GW), the IP-SM-GW serving a user for a Short Message Service (SMS). 
     Embodiment D2. The UDM node of Embodiment D1, wherein the processing circuitry is further configured to cause the UDM node to receive the address of the IP-SM-GW from the HSS node by being configured to cause the UDM node to: 
     receive a registration request to register the IP-SM-GW in a unified data management (UDM) node, the registration request including the address of the IP-SM-GW associated with the user. 
     Embodiment D3. The UDM node of Embodiment D2, wherein the processing circuitry is further configured to cause the UDM node to at least one of: 
     receive a de-registration request to de-register the IP-SM-GW, the de-registration request including the address of the IP-SM-GW; and 
     confirm one of the registration and the de-registration of the IP-SM-GW in a response message. 
     Embodiment D4. The UDM node of any one of Embodiments D2 and D3, wherein the processing circuitry is further configured to cause the UDM node to one or more of: 
     store the address in a unified data repository (UDR) node as part of the registration of the IP-SM-GW; 
     remove the address in the UDR node as part of the registration of the IP-SM-GW; 
     determine whether message waiting data are stored for the user associated with the IP-SM-GW; and/or 
     use the address to communicate with the IP-SM-GW to provide a mobile terminated short message service (MT SMS) to a user equipment (UE) associated with the user. 
     Embodiment D5. The UDM node of Embodiment D1, wherein the processing circuitry is further configured to cause the UDM node to receive the address of the IP-SM-GW by being configured to cause the UDM node to: 
     determine whether the address is available in a home subscriber server (HSS) node by sending a request to the HSS node; and 
     as a result of the request, receive a response from the HSS node, the response including the address of the IP-SM-GW associated with the user. 
     Embodiment D6. The UDM node of Embodiment D1, wherein the processing circuitry is further configured to cause the UDM node to receive the address of the IP-SM-GW from the HSS node by being configured to cause the UDM node to: 
     query a unified data repository (UDR) node for the address of the IP-SM-GW; and 
     responsive to the query, receive the address from the UDR node. 
     Embodiment E1. A home subscriber server (HSS) node, the HSS node comprising processing circuitry, the processing circuitry configured to cause the HSS node to: 
     send, to one of a unified data repository (UDR) node and a unified data management (UDM) node, an address of an Internet Protocol-Short Message-Gateway (IP-SM-GW), the IP-SM-GW serving a user for a Short Message Service (SMS). 
     Embodiment E2. The HSS node of Embodiment E1, wherein the processing circuitry is configured to send, to the UDM node, the address of the IP-SM-GW by being configured to cause the HSS node to: 
     send a registration request to register the IP-SM-GW, the registration request including the address of the IP-SM-GW associated with the user. 
     Embodiment E3. The HSS node of Embodiment E2, wherein the processing circuitry is further configured to cause the HSS node to at least one of: 
     send a de-registration request to de-register the IP-SM-GW, the de-registration request including the address of the IP-SM-GW; and 
     receive a confirmation of one of the registration and the de-registration of the IP-SM-GW in a response message. 
     Embodiment E4. The HSS node of Embodiment E1, wherein the processing circuitry is configured to send, to the UDM node, the address of the IP-SM-GW by being configured to cause the HSS node to: 
     receive a request for the address from the UDM node; and 
     responsive to the request, send a response to the UDM node, the response including the address of the IP-SM-GW associated with the user. 
     Embodiment E5. The HSS node of Embodiment E1, wherein the processing circuitry is configured to send the address of the IP-SM-GW by being configured to cause the HSS node to: 
     send the address of the IP-SM-GW to the UDR node. 
     Embodiment F1. A network node, the network node comprising processing circuitry, the processing circuitry configured to cause the network node to: 
     receive, from a home subscriber server (HSS) node, an address of an Internet Protocol-Short Message-Gateway (IP-SM-GW), the IP-SM-GW serving a user for a Short Message Service (SMS); and 
     as a result of receiving a query from a unified data management (UDM) node for the address of the IP-SM-GW, send the address of the IP-SM-GW to the UDM node. 
     Embodiment F2. The network node of Embodiment F1, wherein the network node is a unified data repository (UDR) node. 
     It should be understood that although the example embodiments discussed herein may use one or another type of message or one or another network node arrangement or context, the techniques disclosed herein may be used with other types of messages or other types of network architecture arrangements or other contexts, to support SMS delivery according to the techniques provided in this disclosure. 
     Some embodiments of the present disclosure provide for one or more new procedures to allow the IP-SM-GW address to become available to the UDM in deployment scenarios where, for example, 2G/3G/4G accesses are not supported and/or support of SMS over IP is to be provided. 
     As will be appreciated by one of skill in the art, the concepts described herein may be embodied as a method, data processing system, and/or computer program product. Accordingly, the concepts described herein may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects all generally referred to herein as a “circuit” or “module.” Furthermore, the disclosure may take the form of a computer program product on a tangible computer usable storage medium having computer program code embodied in the medium that can be executed by a computer. Any suitable tangible computer readable medium may be utilized including hard disks, CD-ROMs, electronic storage devices, optical storage devices, or magnetic storage devices. 
     Some embodiments are described herein with reference to flowchart illustrations and/or block diagrams of methods, systems and computer program products. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. 
     These computer program instructions may also be stored in a computer readable memory or storage medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instruction means which implement the function/act specified in the flowchart and/or block diagram block or blocks. 
     The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. It is to be understood that the functions/acts noted in the blocks may occur out of the order noted in the operational illustrations. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Although some of the diagrams include arrows on communication paths to show a primary direction of communication, it is to be understood that communication may occur in the opposite direction to the depicted arrows. 
     Computer program code for carrying out operations of the concepts described herein may be written in an object oriented programming language such as Java® or C++. However, the computer program code for carrying out operations of the disclosure may also be written in conventional procedural programming languages, such as the “C” programming language. The program code may execute entirely on the user&#39;s computer, partly on the user&#39;s computer, as a stand-alone software package, partly on the user&#39;s computer and partly on a remote computer or entirely on the remote computer. In the latter scenario, the remote computer may be connected to the user&#39;s computer through a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). 
     Many different embodiments have been disclosed herein, in connection with the above description and the drawings. It will be understood that it would be unduly repetitious and obfuscating to literally describe and illustrate every combination and subcombination of these embodiments. Accordingly, all embodiments can be combined in any way and/or combination, and the present specification, including the drawings, shall be construed to constitute a complete written description of all combinations and subcombinations of the embodiments described herein, and of the manner and process of making and using them, and shall support claims to any such combination or subcombination. 
     It will be appreciated by persons skilled in the art that the embodiments described herein are not limited to what has been particularly shown and described herein above. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings without departing from the scope of the following claims.