Patent Publication Number: US-2023156447-A1

Title: Roaming device location determination for emergency communications

Description:
BACKGROUND 
     Modern terrestrial telecommunication systems include heterogeneous mixtures of second, third, and fourth generation (2G, 3G, and 4G) cellular-wireless access technologies, which can be cross-compatible and can operate collectively to provide data communication services. Global Systems for Mobile (GSM) is an example of 2G telecommunications technologies; Universal Mobile Telecommunications System (UMTS) is an example of 3G telecommunications technologies; and Long Term Evolution (LTE), including LTE Advanced, and Evolved High-Speed Packet Access (HSPA+) are examples of 4G telecommunications technologies. Telecommunications systems may include fifth generation (5G) cellular-wireless access technologies to provide improved bandwidth and decreased response times to a multitude of devices that may be connected to a network. 
     Telecommunication systems can be associated with different telecommunication service providers. A mobile device can be considered a roaming device when it operates on a network of a telecommunication service provider that is different from the telecommunication service provider with which the device is registered (e.g., pays a fee to receive service). To process a call and/or text while roaming, the telecommunication service provider hosting the roaming device may forward the call to the “home” telecommunication service provider with which the roaming device is registered. In the context of an emergency text communication, the “home” telecommunication service provider is responsible for determining a geographical location of registered devices. However, when a device registered with the “home” telecommunication service provider is a roaming device, the geographical location of the roaming device cannot be determined by the “home” telecommunication service provider due to the roaming device utilizing a different telecommunications service provider. In examples when the roaming device sends a communication requesting emergency service, the “home” telecommunication service provider is unable to send the communication to an emergency service provider because the geographical location of the roaming device is needed to configure the communication for sending to the emergency service provider. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description is set forth with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items or features. 
         FIG.  1    depicts an example network environment in which an example user equipment can connect to a telecommunication system that includes an example location server to implement the techniques described herein. 
         FIG.  2    depicts another example network environment in which an example user equipment can connect to a telecommunication system that includes an example location server to implement the techniques described herein. 
         FIG.  3    depicts an example system architecture for a fifth generation (5G) telecommunication network. 
         FIG.  4    depicts an example Gateway Mobile Location Center (GMLC)) implementing techniques to determine a geographical location of an example user equipment (UE) operating as a roaming device. 
         FIG.  5    depicts a messaging flow during an example call setup through an example Gateway Mobile Location Center (GMLC). 
         FIG.  6    depicts another Session Initiation Protocol (SIP) messaging flow during an example call setup through an example Gateway Mobile Location Center (GMLC). 
         FIG.  7    depicts a flowchart of an example process for determining a location of an example user equipment roaming on a host telecommunications system. 
         FIG.  8    depicts an example system architecture for a user equipment. 
     
    
    
     DETAILED DESCRIPTION 
     This application describes techniques for determining supplemental information for an emergency communication originating by a roaming device. For example, the techniques can include determining location information and/or user information associated with a roaming device that initiates text message for communication with a Public Agency that provides emergency services. Using the techniques described herein, a network provider hosting the roaming device can implement a server to generate, identify, or otherwise determine data including location data, emergency contact data, and/or medical data, just to name few. The server can send the data to a Public Agency Gateway that associates, appends, or otherwise includes the supplemental information with the emergency communication initiated by the roaming device (e.g., a device operating outside an area served by a telecommunication service provider with which the device is registered). In this way, the communication initiated by the roaming device can be routed to a device associated with a closest available Public Agency (Police, Fire, Medical Services, etc.). 
     Generally, the techniques described herein can include appending geographical location information to a communication originating by a roaming device. That is, the techniques enable substantially real-time location determination of roaming devices for sending to a Public Service Answering Point (PSAP). For instance, the roaming device may wish to send a voice, text, and/or video message to a 911 call center, and a server of a host service provider can exchange data with a Public Agency Gateway and a home service provider to determine the geographical location of the roaming device. The server can receive a request from the Public Agency Gateway for location information and use one or more location techniques to ping, page, or otherwise locate the roaming device in an environment of the host service provider. In this way, the communication (e.g., a text to the 911 call center) that would otherwise be undeliverable (e.g., a location is required to determine the closest PSAP) can instead by communicated to the PSAP. 
     In some examples, the locating techniques described herein can include a visiting network provider employing a server that determines supplemental information for appending to a communication between a roaming device and a device associated with a Public Agency. The visiting network provider can send the communication request to a home network provider which in turn sends the communication to a Public Agency Gateway. Generally, the Public Agency Gateway creates a communication session between the roaming device and a device associated with the Public Agency. The home network provider can send a network identifier (e.g., a name of the network providing service to the roaming device) to the Public Agency Gateway to indicate that the visiting network provider is to provide location information. The server can receive a request for the location information from the Public Agency Gateway and send a message to a registry (e.g., a Home Subscriber Server (HSS), a Home Location Register (HLR), a Unified Data Management (UDM), and the like) of the home network provider requesting the serving node (network location, cell, base station, etc.) used by the roaming device when generating the request for a communication session. The server can determine a geographical location of the roaming device based on the serving node information received from the registry (e.g., the server can initiate a location determination procedure by communicating with the roaming device and/or the serving node). The geographical location can represent a current location within an area of the serving node. The server can transmit the geographical location to the Public Agency Gateway which can use the geographical location to establish the communication session with the device associated with the Public Agency. For example, the location techniques performed by the server can enable the Public Agency Gateway to select a PSAP for the communication session based on which available PSAP can best serve the emergency (e.g., a PSAP closest to the geographical location). 
     In some examples, a system can implement a server that is configured to determine a geographical location of the roaming device based at least in part on transmitting and/or receiving data with a Gateway associated with the Public Agency and a server of a home network provider. For instance, data associated with a network identifier and/or a serving node can be used to initiate a location operation. In some examples, the server (e.g., a Gateway Mobile Location Center (GMLC)) can send a geographical location request to a network element (e.g., a Mobile Management Entity (MME), an Enhanced Serving Mobile Location Center (ESMLC), an Access and Mobility Management Function (AMF), or other network element) and receive the geographical location of the roaming device based on the network element implementing the location operation. In such examples, the system can send the geographical location information to the Gateway that is configured to associate the geographical location with emergency communication data as a communication session (e.g., a voice or text message) between the roaming device and the PSAP. 
     The systems and techniques disclosed herein may provide emergency location(s) of a roaming device by employing a server that can receive, determine, generate and/or format communications between devices of a Public Agency Gateway associated with an emergency control center and a home network provider. In this way, geographical location data of the roaming device (e.g., a user equipment (UE), an Internet of Things device, a Machine to Machine device, a vehicle computing device, an aerial vehicle device, and so on) is available to enable the Public Agency Gateway to establish an emergency communication with a PSAP. In some examples, the server may send a first request for information from the home service provider, and receive a general network location (e.g., a location of a network element) and/or user information associated with the roaming device from the home service provider based on the first request. The server may also or instead send a second request for a geographical location to network elements) of the host service provider based on the general network location. Upon receiving the geographical location based on the second request from the network element(s), the server can transmit data representing the geographical location to a Public Agency Gateway that uses the geographical information to format the communication for exchange with the emergency control center. By using the systems and techniques disclosed herein, communication requests from the roaming device can be associated with a geographical location that would otherwise be unavailable because the device is roaming. 
     The techniques described herein can enable secure data exchange between a UE and a PSAP over a core network including initiating, establishing, maintaining, or otherwise determining a message that includes supplemental information (e.g., location data, user data, etc.). By way of example and not limitation, a UE may send a message comprising an image, text, or a video of an emergency event (e.g., a medical event, a criminal event, an environmental event, and so on) proximate to the UE to a PSAP responsible for receiving emergency communications. In such an example, a server associated with a host service provider may enable a Public Agency Gateway to augment or adjust the message with the supplemental information. Further description of establishing the message between the UE and the PSAP can be found throughout this disclosure including in the figures below. 
       FIG.  1    depicts an example network environment  100  in which an example user equipment (UE) can connect to a host telecommunication system to engage in communication sessions for voice calls, video calls, messaging, data transfers, or other types of communications. For example, a UE  102  can connect to a host telecommunication system  104  for sending an emergency message  106  to an emergency service center  108  (e.g., a PSAP or other public emergency service). Using the techniques described herein, a location of the UE  102 , user information (e.g., medical information), and the like can be shared with the emergency service center  108  to enable an improved response to a medical event, a crime in progress, a natural disaster, and so on. 
     The UE  102  represents any device that can wirelessly connect to the telecommunication network, and in some examples may include a mobile phone such as a smart phone or other cellular phone, a personal digital assistant (PDA), a personal computer (PC) such as a laptop, desktop, or workstation, a media player, a tablet, a gaming device, a smart watch, a hotspot, or any other type of computing or communication device. An example architecture for the UE  102  is illustrated in greater detail in  FIG.  7   . 
     In various examples, the host telecommunication system  104  can represent functionality to provide communications between the UE  102  and the emergency service center  108 , and can include one or more radio access networks (RANs), as well as one or more core networks linked to the RANs. For instance, the UE  102  can wirelessly connect to a base station or other access point of a RAN, and in turn be connected to the core network(s). The RANs and/or core networks can be compatible with one or more radio access technologies, wireless access technologies, protocols, and/or standards. For example, wireless and radio access technologies can include fifth generation (5G) technology, Long Term Evolution (LTE)/LTE Advanced technology, other fourth generation (4G) technology, High-Speed Data Packet Access (HSDPA)/Evolved High-Speed Packet Access (HSPA+) technology, Universal Mobile Telecommunications System (UMTS) technology, Global System for Mobile Communications (GSM) technology, WiFi® technology, and/or any other previous or future generation of radio access technology. In this way, the host telecommunication system  104  is compatible to operate with other radio technologies including those of other service providers (e.g., the host telecommunications system  104 ). Accordingly, a message from the UE  102  may be processed by host telecommunication system  104  independent of the technology used by the UE  102 . 
     In some examples, the UE  102  can generate the emergency message  106  (e.g., voice, text, and/or video) that includes a connection request to the emergency service center  108  (e.g., a Public Agency such as Fire, Police, Medical, and so on). In some examples, the emergency message  106  can represent a text from the UE  102  to a 911 call center while the UE  102  is roaming (e.g., receiving service outside an area of the home telecommunications system  110 ). 
     The host telecommunication system  104  can send the emergency message  106  (or a portion thereof) through the core network for processing by a home telecommunications system  110  (e.g., a system that the UE  102  is registered to receive service for a fee). In various examples, the home telecommunication system  110  can authenticate a user of the UE  102 , identify a network element (a cell, an antennae, a transceiver, a base station, etc.) of the core network serving the UE  102 , verify an amount of data available to complete the emergency message  106 , and/or store user information (e.g., contact information, medical records, emergency contact information, etc.). Generally, the host telecommunication system  104  can represent a visiting network provider and the home telecommunications system  110  can represent a home network provider. 
     As depicted in  FIG.  1   , the host telecommunication system  104  comprises a location server  112  that is configured to implement different locating techniques to provide a geographical location  114  of the UE  102  to a Public Agency Gateway (PAG)  116 . The location server  112  can initiate request(s) to locate the UE  102  to one or more network elements (also referred to as “network nodes”) of the host telecommunication system  104 . For instance, the location server  112  can send a request for a current location of the UE  102  to an MME that is configured to location the UE  102  relative to the network element and/or relative to a map coordinate system. The location server  112  can, in some examples, receive the geographical location  114  of the UE  102  from the MME (or other network element) depending on a type of technology used to locate the UE  102 . In various examples, the geographical location  114  can represent a position of the UE  102  relative to a map coordinate system (e.g., a location in an environment with longitude, latitude, elevation, etc.). 
     The PAG  116  is configured to establish a communication session between the UE  102  and the emergency service center  108 . The communication session can include one or more of: a transmission control protocol (TCP), an internet protocol (IP), a user datagram protocol (UDP), a simple mail transport protocol (SMTP), a file transfer protocol (FTP), a hypertext transfer protocol (HTTP), or a hypertext transfer protocol secure (HTTPS). Based on receiving the geographical location  114  from the location server  112 , the PAG  116  can generate an emergency message with geographical location  118  for sending to the emergency service center  108 . 
     Generally, the location server  112  can exchange data  120  with a subscriber database  122  (or other component) of the home telecommunication system  110 . The data  120  can represent data associated with the emergency message  106  and can include one or more of: a network identifier of the UE  102 , a request for location information, a location of the network element serving the UE  102 , user information data, and the like. In some examples, the subscriber database  122  can include serving node information captured by the home telecommunication system  110  during a registration process for services and/or responsive to the UE  102  changing to another serving node. 
     As mentioned, the location server  112  can determine the geographical location  114  of the UE  102  based at least in part on the data  120 . For instance, the location server  112  can send a request to the subscriber database  122  for a network location associated with the emergency message  106  (e.g., the network element that received the emergency message  106 ). In such examples, the location server  112  can determine the geographical location  114  based at least in part on the data  120  indicating the location of the network element serving the UE  102 . That is, the location server  112  can send a geographical location request to the network element to determine a more precise location of the UE  102  than the location of the network element. In this way, the location server  112  can initiate an exact position (e.g., within one meter) for the UE  102  within an area of the network element. 
     In some examples, the home telecommunication system  110  can send the data  120  representing medical information, emergency contact information, or other user information to the location server  112  which can forward the data  120  to the PAG  116  for appending to the emergency message  106 . Accordingly, the location server  112  can remotely access the data  120  from the home telecommunication system  110  to aggregate or otherwise determine information usable to perform various locating techniques and/or to improve the content of the emergency message  106  (e.g. to automatically generate useful information for the emergency service center  108  that is not otherwise included in the emergency message  106 . 
     In some examples, the host telecommunication system  104  can determine that the UE  102  is a roaming device based at least in part on the network identifier associated with the emergency message  106 , and generate a request for device data (e.g., data indicating that the UE  102  has credit to complete the communication session involving the emergency message  106 ), network location data (the location of the network element serving the UE  102 ), or user data (is any user information available that can be included in the emergency message  106 ) for sending to the home telecommunication system  110 . 
     The subscriber database  122  (e.g., a Home Subscriber Server) of the home telecommunication system  110  can receive, manage, and otherwise store subscriber information including the device data, the network location data, and/or the user data. For instance, the subscriber database  122  can be configured as to send and/or receive user information, registration information, motion information, and other information associated with the UE  102  with the location server  112 . 
     Generally, the location server  112  can receive the data  120  (e.g., the location of the network element) from the home telecommunication system  110  and determine the geographical location  114  of the UE  102  using one or more locating techniques. In various examples, the location server  112  can generate a request to ping, page, or otherwise locate the UE  102  within the host telecommunication system  104 . In some examples, the data  120  can identify a serving node (or network element) used to provide service to the UE  102 , and the location server  112  can initiate a locating technique to locate the UE  102  in the serving node (e.g., send a request for a location to an MME, AMF, ESMLC, and the like). The PAG  116  can establish the communication session between the UE  102  and the emergency service center  108  based at least in part on the geographical location  114  which otherwise could not be completed due to a lack of a geographical location of the UE  102  (e.g., the roaming device) being known by the home telecommunication system  110 . 
     By implementing the techniques described herein, the location server  112  can initiate, identify, or otherwise determine the geographical location  114  usable for the PAG  116  to complete communications between the  102  UE and the emergency service center  108  including when the UE  102  is roaming on to the host telecommunication system  104 . Additional detail for using the location server  112  to perform locating techniques is discussed throughout this disclosure including in the descriptions of the other figures. 
       FIG.  2    depicts another example network environment in which an example user equipment can connect to a telecommunication system that includes an example location server to implement the techniques described herein. For example, the UE  102  can connect to the host telecommunication system  104  using a core network  202  and/or the home telecommunication system  110  using a core network  204  to send the emergency message  106  to the emergency service center  108 . 
     The core network  202  and/or the core network  204  can, in some examples, determine a connection between the UE  102 , the emergency service center  108 , the location server  112 , the PAG  116  that configures the emergency message  106  with the geographical location  114 . For example, the UE  102 , the location server  112 , the PAG  116 , and/or the subscriber database  122  can exchange Session Initiation Protocol (SIP) messages to set up and manage individual communication sessions. Further discussions of exchanging a SIP message are included throughout this disclosure including in  FIGS.  5  and  6   . 
     In some examples, the core network  202  and/or the core network  204  can represent a service-based architecture that includes multiple types of network functions that process control plane data and/or user plane data to implement services for the UE  102 . In some examples, the services comprise the emergency communications (e.g., the emergency message  106 , the emergency message with geographical location  118 , and the like) which may include a text, a data file transfer, an image, a video, a combination thereof, and so on. The network functions of the core network  202  and/or the core network  204  can include an Access and Mobility Management Function (AMF), a Session Management Function (SMF), a User Plane Function (UPF), a Policy Control Function (PCF), and/or other network functions implemented in software and/or hardware, just to name a few. Examples of network functions are also discussed in relation to  FIG.  3   , and elsewhere. 
       FIG.  3    depicts an example system architecture for a fifth generation (5G) telecommunication network. In some examples, the telecommunication network can comprise the core network  202  and/or the core network  204  in  FIG.  2    that includes a service-based system architecture in which different types of network functions (NFs)  302  operate alone and/or together to implement services. Standards for 5G communications define many types of NFs  302  that can be present in 5G telecommunication networks (e.g., the core network  202  or the core network  204 ), including an Authentication Server Function (AUSF), Access and Mobility Management Function (AMF), Data Network (DN), Unstructured Data Storage Function (UDSF), Network Exposure Function (NEF), Network Repository Function (NRF), Network Slice Selection Function (NSSF), Policy Control Function (PCF), Session Management Function (SMF), Unified Data Management (UDM), Unified Data Repository (UDR), User Plane Function (UPF), Application Function (AF), User Equipment (UE), (Radio) Access Network ((R)AN), 5G-Equipment Identity Register (5G-EIR), Network Data Analytics Function (NWDAF), Charging Function (CHF), Service Communication Proxy (SCP), Security Edge Protection Proxy (SEPP), Non-3GPP InterWorking Function (N3IWF), Trusted Non-3GPP Gateway Function (TNGF), and Wireline Access Gateway Function (W-AGF), many of which are shown in the example system architecture of  FIG.  3   . 
     One or more of the NFs  302  of the core network  202  and/or the core network  204  can be implemented as network applications that execute within containers (not shown). 5G NFs  302  can execute as hardware elements, software elements, and/or combinations of the two within telecommunication network(s), and accordingly many types of 5G NFs  302  can be implemented as software and/or as virtualized functions that execute on cloud servers or other computing devices. Network applications that can execute within containers can also include any other type of network function, application, entity, module, element, or node. 
       FIG.  2    further depicts the host telecommunication system  104  sending the emergency message  106  to the home telecommunication system  110  based at least in part on an indication that the UE  102  is a roaming device. Accordingly, the home telecommunication system  110  can verify an identity of a user of the UE  102 , an amount of credit (e.g., verifies an amount of available data to complete a communication), and so on, to connect the emergency message  106 . In some examples, the home telecommunication system  110  can send a client identifier  206  to the PAG  116  usable to identify which network provider is receiving the emergency message  106 . In such examples, the PAG  116  can identify the host telecommunication system  104  as generating the emergency message  106  based at least in part on the client identifier  206  (e.g., an identifier associated with the UE  102  such as a Fully Qualified Domain Name (FQDN)). 
     In some examples, the PAG  116  can generate a location request  208  (e.g., a communication, a message, etc.) for sending over a core network (e.g., the core network  202  and/or the core network  204 ) to the location server  112  of the host telecommunication system  104 . Based at least in part on receiving the location request  208 , the location server  112  can communicate with the subscriber database  122  (by exchanging the data  120 ) to determine a location of the UE  102  relative to a network element (also referred to as a “serving node”) such as a base station, an antennae, a transceiver, among others. The subscriber database  122  can send a network location to the location server  112  that indicates the network element serving the UE  102 . This enables the location server  112  to initiate a location test (e.g., paging or pinging the UE  102 , etc.) using a most effective location determination technique for the identified network element. 
     As shown in  FIG.  2   , the location server  112  comprises a location determination component  210  that is configured to determine the geographical location  114  by generating a message requesting a current location of the UE  102  relative to the network element or a coordinate system. In some examples, the location determination component  210  can communicate with different network element types to send the message, and receive graphical location data representing the current location of the UE  102 . 
       FIG.  2    further depicts the location server  112  transmitting the geographical location  114  to the PAG  116  for appending to the emergency message  106 . For example, the home telecommunication system  110  can forward the emergency message  106  to the PAG  116  after identifying that the UE  102  is roaming and therefore the home telecommunication system  110  is unable to locate the UE  102 . In various examples, the PAG  116  can add, modify, or otherwise append the geographical location  114  to the emergency message  106  to form the emergency message with geographical location  118 . The emergency service center  108  can use the emergency message with geographical location  118  to format a first communication as well as subsequent communication(s) with the UE  102 . In examples when the emergency service center  108  represents a PSAP, the PAG  116  can use the geographical location  114  to select a closest available PSAP from a set of available PSAPs to receive the emergency message with geographical location  118 . Further description of determining a location of a roaming device can be found throughout this disclosure. 
       FIG.  4    depicts an example Gateway Mobile Location Center (GMLC)) implementing techniques to determine a geographical location of an example user equipment (UE) operating as a roaming device. For instance, a UE  402  operating on a first telecommunication system  404  (e.g., a host network provider) can generate an emergency text message, and a GMLC  406  can determine a geographical location of the UE  402  usable to connect the UE  402  with a PSAP  408 . In some examples, the GMLC  406  can provide the functionality of the location server  112 . 
     In some examples, the UE  402  can send the text message to a network element  410  (e.g., a base station, an antennae, a transceiver, or other serving node). The first telecommunication system  404  can identify that the UE  402  is a roaming device and send the text message to a second telecommunication system  412  (e.g., a home network provider) for authentication, charging, etc. In particular, the network element can use a core network to transmit the text message to an IP multimedia subsystem (IMS)  414  which can forward the text message to a Short Message Service Center (SMSC)  416  for processing. The SMSC  416  can transmit the text message to a Text Control Center (TCC)  418  that is configured to establish a communication session between the UE  402  and the PSAP  408 . In various examples, the TCC  418  can provide the functionality of the Public Agency Gateway  116 . 
     The TCC  418  can, for example, send a location message requesting a location of the UE  402  to the GMLC  406  based at least in part on a network identifier identifying the UE  402  as operating on the first telecommunications system  404 . For example, the second telecommunication system  412  can send the text message along with the network identifier to the TCC  418  to generate an initial communication session with the PSAP  408 . In various examples, communications between the TCC  418  and the GMLC  406  can include a Mobile Location Protocol (MLP). 
     The GMLC  406  can, in some examples, utilize a Diameter Routing Agent (DRA)  420  of the first telecommunication system  404  for sending a network location request to a Diameter Routing Agent (DRA)  420  of the second telecommunication system  412 . The DRA  420  and the DRA  422  can use an SLh interface and/or an SLg interface to send communications between the GMLC  406  and a Home Subscriber Server (HSS)  424 . 
     Generally, the HSS  424  can provide functionality of the subscriber database  122  including storing network information, device information, and user information. In some examples, the HSS  424  can send information about the network element  410  used by the UE  402  when sending the text message. The GMLC  406  can utilize the DRA  420  to send a request for a geographical location of the UE  402  to the network element  410 . In this way, the network element  410  can implement one or more locating techniques to locate a position of the UE  402  in a map coordinate system. That is, the GMLC  406  can determine the geographical location of the UE  402  (e.g., a two dimensional or three dimensional location). In one specific example, the GMLC  406  can locate the UE  402  on a specific floor of a building or other structure to provide a current location of the UE  402  requesting emergency service. 
     In some examples, the HSS  424  can also communicate user information usable by the PSAP  408  to provide emergency service. For example, the GMLC  406  can request, query, receive, or otherwise access emergency contract information, medical information, or other user information from the HSS  424  to provide the PSAP  408  with helpful information in addition to the geographical location. The GMLC  406  can, for example, send the geographical location and user information to the TCC  418 , and the TCC  418  can determine a communication session between the UE  402  and the PSAP  408  that includes the geographical location and the user information. 
       FIG.  5    depicts a messaging flow during an example call setup through an example Gateway Mobile Location Center (GMLC). In some examples, the messaging flow as shown in  FIG.  5    can represent activity to determine supplemental data by the GMLC  406  during the establishing and maintaining of a communication (e.g., the emergency message  106 , the emergency message with geographical location  118 ) between the UE  102  and PSAP  408 . For example, the UE  402  can initiate a text message for sending to the PSAP  408 , and the GMLC  406  can provide geographical location data to the TCC  418  based on data exchanged with the HSS  424  and the network element  410 . 
     In some examples, the massage flow can include messaging associated with an IMS, such as a Session Initiation Protocol (SIP) messaging flow, while in other examples the message flow can represent a messaging flow that does not include communications with an IMS. 
     The messaging flow as shown in  FIG.  5    can include the UE  402  sending a calling line identification restriction (CLIR) to the GMLC  406  usable for the GMLC  406  to determine that the UE  402  is a roaming device. For example, the CLIR can include a subscriber identifier (e.g., a Mobile Station Integrated Services Digital Network (MSISDN)) and an indication that the message is associated with an emergency intended for a PSAP. 
     Responsive to determining that the UE  402  is roaming, the GMLC  406  can send a Send Routing Information (SRI) and/or a Response to Information Request (RIR) to the HS S  424  via the DRA  420  and the DRA  422 . The SRI and/or the RIR can include the MSISDN for sharing with the HSS  424 . The messaging flow can also include the HSS  424  sending an SRI response to the GMLC  406  usable for the GMLC  406  to identify network element information (e.g., a network element identity, location, etc.) associated with the text message by the UE  402 . 
     The messaging flow of  FIG.  5    can also include the GMLC  406  sending a provide location request (PLR) to the HSS  424  which can return a provide location answer (PLA). For instance, the MSISDN can identify the UE  402  and the PLA can include a location estimation of the UE  402  relative to the network element  410 . In some examples, the network element can represent an MME, an AMF, an ESMLC, a Location Management Function (LMF), or other entity responsible for determining a geographical location of the UE  402 . 
     The GMLC  406  can initiate a PLR to the network element  410  based at least in part on the PLA received from the HSS  424 , and receive a PLA from the network element  410  indicating a geographical location of the UE  402 . In various examples, the GMLC  406  can send a Standard Location Immediate Answer (SLIA) to the UE  402 . 
       FIG.  6    depicts another Session Initiation Protocol (SIP) messaging flow during an example call setup through an example Gateway Mobile Location Center (GMLC). For instance,  FIG.  6    can show additional detail of the exchange between the GMLC  406  and the HSS  424 . 
     The messaging flow as shown in  FIG.  6    can include the first telecommunication system  404  and the second telecommunication system  412  exchanging device information, network information, and/or user information between the GMLC  406 . For instance, the GMLC  406  can send a diameter Response to Information Request (RIR) to the DRA  420  which can use an SLh interface and/or an SLg interface to communicate with the DRA  422 . In some examples, the DRA  422  can send the diameter RIR to the HSS  424  and the HSS  424  can return a diameter Response to Information Answer (RIA) to the GMLC  406  via the DRA  422  and the DRA  420 . 
       FIG.  7    depicts a flowchart of an example process  700  for determining a location of an example user equipment roaming on a host telecommunications system. Some or all of the process  700  may be performed by one or more components in  FIGS.  1 - 6   , as described herein. For example, some or all of process  700  may be performed by the location server  112  and/or the GMLC  406 . 
     At operation  702 , the process may include receiving, by a server of a host network and from a Public Agency Gateway, a first communication requesting location information associated with a first device operating outside a coverage area of a home network, the Public Agency Gateway (PAG) configured to establish an emergency communication between the first device and a second device associated with a Public Service Answering Point (P SAP). In some examples, the operation  702  may include the location server  112  (or the GMLC  406 ) receiving a location request from the PAG  116  (or TCC  418 ) to initiate a communication session between a roaming device (e.g., UE  102  or UE  402 ) and another device associated with the PSAP. 
     By way of example and not limitation, a UE of a first telecommunication system that includes a core network can send an emergency message comprising an image, a video, and/or a file transfer to an emergency service center (e.g., a 911 Center) associated with the PSAP (e.g., PSAP  408 ). A second telecommunication system (e.g., a home network) can send the emergency message to the PAG to cause the PAG to generate the first communication to the location server  112  of the first telecommunication system. Communications including the request for location information can include the location server  112  and the PAG  116  implementing a Mobile Location Protocol or a web service. 
     At operation  704 , the process may include sending, by the server and to a Home Subscriber Server of the home network, a second communication requesting network node information associated with the first device. In some examples, the operation  704  may include the location server  112  sending a communication to the subscriber database  122  (or the HSS  424 ) to identify a network element (or serving node) serving the UE (the first device) that originated the emergency message. For instance, the location server  112  can generate a message requesting a location of the UE relative to the network element (e.g., a network location). In various examples, transmitting the second communication can include using one or more Diameter Routing Agents associated with the home network and the subscriber database  122 . Using the techniques described herein, the location server  112  can exchange data with the subscriber database  122  to determine a geographical location of the first device to establish a communication session with the PSAP. 
     At operation  706 , the process may include receiving, by the server and from the Home Subscriber Server, an identification of a serving node in the host network in communication with the first device. In some examples, the operation  706  may include the subscriber database  122  (or the HSS  424 ) sending the location server  112  data representing an identifier and/or a location of the serving node that received the emergency message from the first device. In various examples, the serving node can comprise information about the network elements providing service to the first device. In one specific example, the identification of the serving node can include a Fully Qualified Domain Name (FQDN). 
     At operation  708 , the process may include sending, by the server and based at least in part on the identification of the serving node, a third communication to a network node requesting a geographical location of the first device within the host network. In some examples, the operation  708  may include the location server  112  sending a request for a geographical location of the first device (e.g., coordinates relative to a coordinate system, etc.) to an entity of the host network (e.g., a node associated with the FQDN). 
     At operation  710 , the process may include receiving, by the server and from the network node, the geographical location indicating a position of the first device relative to a map coordinate system. In some examples, the operation  710  may include the location server  112  receiving the geographical location  114  based at least in part on the third communication. For example, the GMLC  406  can send a request for the geographical location to the network node which performs a locating technique, and returns the geographical location of the first device to the GMLC  406 . 
     At operation  712 , the process may include sending, by the server and to the Public Agency Gateway, the geographical location of the first device for associating with the emergency communication. In some examples, the operation  712  may include the location server  112  sending the geographical location  114  to the PAG  116  for appending to the emergency message  106 . In other examples, the GMLC  406  may also send user information to the PAG  116  for associating with the emergency communication. Sending the geographical and/or user information to the PAG  116  can cause the PAG  116  to configure the emergency message with supplemental information usable to establish a communication session with a device of a Public Service Answering Point. In some examples, the process can include additional operations to continuously determine the geographical location of the first device to maintain, track, or otherwise determine a current geographical location the first device over time. 
       FIG.  8    depicts an example system architecture for a UE  102 , in accordance with various examples. As shown, a UE  102  can have memory  802  storing a call setup manager  804 , and other modules and data  806 . A UE  102  can also comprise processor(s)  808 , radio interfaces  810 , a display  812 , output devices  814 , input devices  816 , and/or a machine readable medium  818 . 
     In various examples, the memory  802  can include system memory, which may be volatile (such as RAM), non-volatile (such as ROM, flash memory, etc.) or some combination of the two. The memory  802  can further include non-transitory computer-readable media, such as volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information, such as computer readable instructions, data structures, program modules, or other data. System memory, removable storage, and non-removable storage are all examples of non-transitory computer-readable media. Examples of non-transitory computer-readable media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile discs (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium which can be used to store desired information and which can be accessed by the UE  102 . Any such non-transitory computer-readable media may be part of the UE  102 . 
     The call setup manager  804  can send and/or receive messages comprising RCS service including SIP messages associated with setup and management of a call session via the IMS  414 . The SIP messages can include any of the SIP messages shown in  FIGS.  5  and  6   , and/or other SIP messages. 
     The other modules and data  806  can be utilized by the UE  102  to perform or enable performing any action taken by the UE  102 . The modules and data  806  can include a UE platform, operating system, and applications, and data utilized by the platform, operating system, and applications. 
     In various examples, the processor(s)  808  can be a central processing unit (CPU), a graphics processing unit (GPU), or both CPU and GPU, or any other type of processing unit. Each of the one or more processor(s)  808  may have numerous arithmetic logic units (ALUs) that perform arithmetic and logical operations, as well as one or more control units (CUs) that extract instructions and stored content from processor cache memory, and then executes these instructions by calling on the ALUs, as necessary, during program execution. The processor(s)  808  may also be responsible for executing all computer applications stored in the memory  802 , which can be associated with common types of volatile (RAM) and/or nonvolatile (ROM) memory. 
     The radio interfaces  810  can include transceivers, modems, interfaces, antennas, and/or other components that perform or assist in exchanging radio frequency (RF) communications with base stations of the telecommunication network, a Wi-Fi access point, and/or otherwise implement connections with one or more networks. For example, the radio interfaces  810  can be compatible with multiple radio access technologies, such as 5G radio access technologies and 4G/LTE radio access technologies. Accordingly, the radio interfaces  810  can allow the UE  102  to connect to the host telecommunication system  104  and/or the home telecommunications system  110  described herein. 
     The display  812  can be a liquid crystal display or any other type of display commonly used in UEs  102 . For example, display  812  may be a touch-sensitive display screen, and can then also act as an input device or keypad, such as for providing a soft-key keyboard, navigation buttons, or any other type of input. The output devices  814  can include any sort of output devices known in the art, such as the display  812 , speakers, a vibrating mechanism, and/or a tactile feedback mechanism. Output devices  814  can also include ports for one or more peripheral devices, such as headphones, peripheral speakers, and/or a peripheral display. The input devices  816  can include any sort of input devices known in the art. For example, input devices  816  can include a microphone, a keyboard/keypad, and/or a touch-sensitive display, such as the touch-sensitive display screen described above. A keyboard/keypad can be a push button numeric dialing pad, a multi-key keyboard, or one or more other types of keys or buttons, and can also include a joystick-like controller, designated navigation buttons, or any other type of input mechanism. 
     The machine readable medium  818  can store one or more sets of instructions, such as software or firmware, that embodies any one or more of the methodologies or functions described herein. The instructions can also reside, completely or at least partially, within the memory  802 , processor(s)  808 , and/or radio interface(s)  810  during execution thereof by the UE  102 . The memory  802  and the processor(s)  808  also can constitute machine readable media  818 . 
     The various techniques described herein may be implemented in the context of computer-executable instructions or software, such as program modules, that are stored in computer-readable storage and executed by the processor(s) of one or more computing devices such as those illustrated in the figures. Generally, program modules include routines, programs, objects, components, data structures, etc., and define operating logic for performing particular tasks or implement particular abstract data types. 
     Other architectures may be used to implement the described functionality and are intended to be within the scope of this disclosure. Furthermore, although specific distributions of responsibilities are defined above for purposes of discussion, the various functions and responsibilities might be distributed and divided in different ways, depending on circumstances. 
     Similarly, software may be stored and distributed in various ways and using different means, and the particular software storage and execution configurations described above may be varied in many different ways. Thus, software implementing the techniques described above may be distributed on various types of computer-readable media, not limited to the forms of memory that are specifically described. 
     CONCLUSION 
     Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example embodiments. 
     While one or more examples of the techniques described herein have been described, various alterations, additions, permutations and equivalents thereof are included within the scope of the techniques described herein. 
     In the description of examples, reference is made to the accompanying drawings that form a part hereof, which show by way of illustration specific examples of the claimed subject matter. It is to be understood that other examples can be used and that changes or alterations, such as structural changes, can be made. Such examples, changes or alterations are not necessarily departures from the scope with respect to the intended claimed subject matter. While the steps herein can be presented in a certain order, in some cases the ordering can be changed so that certain inputs are provided at different times or in a different order without changing the function of the systems and methods described. The disclosed procedures could also be executed in different orders. Additionally, various computations that are herein need not be performed in the order disclosed, and other examples using alternative orderings of the computations could be readily implemented. In addition to being reordered, the computations could also be decomposed into sub-computations with the same results.