Patent Publication Number: US-2023144916-A1

Title: Location Determination and Telephone Number Distribution for Emergency Calls

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation of U.S. application Ser. No. 17/390,536, filed Jul. 30, 2021, the entire disclosure of which is herein incorporated by reference. 
    
    
     BACKGROUND 
     Enterprise entities rely upon several modes of communication to support their operations, including telephone, email, internal messaging, and the like. These separate modes of communication have historically been implemented by service providers whose services are not integrated with one another. The disconnect between these services, in at least some cases, requires information to be manually passed by users from one service to the next. Furthermore, some services, such as telephony services, are traditionally delivered via on-premises systems, meaning that remote workers and those who are generally increasingly mobile may be unable to rely upon them. One type of system which addresses problems such as these includes a unified communications as a service (UCaaS) platform, which includes several communications services integrated over a network, such as the Internet, to deliver a complete communication experience regardless of physical location. 
     SUMMARY 
     Disclosed herein are, inter alia, implementations of systems and techniques for location determination and telephone number distribution for emergency calls. 
     One aspect of this disclosure is a method, which includes determining a location of a calling device responsive to the calling device initiating an emergency call to a public safety answering point (PSAP), determining a pool of telephone numbers associated with the location of the calling device, distributing a telephone number from the pool of telephone numbers to the calling device for use with the emergency call, and facilitating the emergency call between the calling device and the PSAP based on the telephone number. 
     Another aspect of this disclosure is an apparatus, which includes a memory and a processor configured to execute instructions stored in the memory to select a pool of telephone numbers from a plurality of pools of telephone numbers based on a location of a calling device, and distribute a telephone number from the pool of telephone numbers to the calling device for use with an emergency call between the calling device and a PSAP. 
     Yet another aspect of this disclosure is a non-transitory computer readable medium storing instructions operable to cause one or more processors to perform operations, which include determining a location of a calling device based on network information within a detectable range of the calling device, selecting a pool of telephone numbers from a plurality of pools of telephone numbers based on the location of a calling device, and facilitating an emergency call between the calling device and a PSAP based on a telephone number from the pool of telephone numbers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       This disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to-scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. 
         FIG.  1    is a block diagram of an example of an electronic computing and communications system. 
         FIG.  2    is a block diagram of an example internal configuration of a computing device of an electronic computing and communications system. 
         FIG.  3    is a block diagram of an example of a software platform implemented by an electronic computing and communications system. 
         FIG.  4    is a block diagram of an example of a system for location determination and telephone number distribution for emergency calls. 
         FIG.  5    is a block diagram of examples of telephone number pools associated with different regions. 
         FIG.  6    is a block diagram of example functionality of emergency calling software. 
         FIG.  7    is a block diagram of an example of a telephony system which determines a location of a calling device and distributes a telephone number to the calling device. 
         FIG.  8    is a flowchart of an example of a technique for location determination and telephone number distribution for emergency calls. 
         FIG.  9    is a flowchart of an example of a technique for determining a location of a calling device. 
         FIG.  10    is a flowchart of an example of a technique for facilitating calls between a calling device and a PSAP. 
     
    
    
     DETAILED DESCRIPTION 
     Customers of a telephony service provider, which may be an entity operating or otherwise providing a UCaaS platform or a separate telephony service entity, may purchase a number of dedicated telephone numbers for assignment to individual or groups of operators. In many cases, such as where a customer of a telephony service provider has hundreds or thousands of operators, it may be more economical to purchase telephone extensions for many of those operators instead of dedicated telephone numbers. Routing rules may then be defined to enable outbound calls from and inbound calls to those telephone extensions as if they were dedicated telephone numbers. 
     However, certain telephony service features which are generally available to operators with dedicated telephone numbers may be unavailable to operators with so-called extension-only operators. In particular, because telephone extensions are typically configured for use within a specific geographic region, such as a country or territory, extension-only operators who are roaming in a different region may be unable to use his or her telephone extension to make an emergency call. Given the always increasing rate of international or otherwise inter-regional travel both for work and personal reasons, this may present a significant challenge for extension-only operators in emergency situations. 
     A conventional approach to addressing this problem is for customers of a telephony service provider to maintain a pool of telephone numbers suitable for emergency call use for their sites. For example, the customer may, through the telephony service provider, arrange for a pool of telephone numbers to be accessible to operators who make emergency calls at one or more specified sites of the customer. Using such an approach, an extension-only operator who is present at a specified site borrows a local telephone number for a temporary period of time to make an emergency call to a local PSAP. Once the emergency call is completed, the telephone number is returned to the pool maintained for the customer site. 
     However, because this conventional approach uses pools of telephone numbers defined at the site-level, it suffers from a major drawback in that a pool of telephone numbers is only available to callers who are physically at the subject site or sites associated with the pool. The pool of telephone numbers only becomes available to the operator upon his or her location being matched to a location of a specified site associated with the pool. As such, when an operator is at a location other than a specified site when traveling abroad, he or she may very well be unable to make an emergency call, thereby potentially placing the health, safety, and/or life of himself or herself or of another person at risk. 
     In one example illustrating this problem, a telephony service provider customer has an extension-only operator who travels from a first region for which his or her telephone extension is configured to a second region (e.g., from the United Kingdom, as the first region, to the United States, as the second region, or vice versa). Although that operator can use his or her telephone extension to make an emergency call in the first region, he or she cannot do so in the second region due to different infrastructure requirements and rules for making emergency calls to local PSAPs. When that operator is at an office of the telephony service provider customer, which is a specified site for which the location is known, he or she may borrow a telephone number from a pool of telephone numbers defined for that site to make an emergency call. However, if that operator goes to an unknown location in that second region, such as a restaurant, a friend&#39;s house, a client&#39;s office, a hotel, a store, or the like, the operator will not be able to borrow a telephone number from a pool to make an emergency call because his or her location is unknown to the system. 
     Implementations of this disclosure address problems such as these using location determination and telephone number distribution for emergency calls, by which a telephony system which maintains multiple pools of telephone numbers, each pool corresponding to a different region such that the pools of telephone numbers are defined at the region-level rather than at the site-level. The telephony system determines the location of a calling device initiating an emergency call regardless of whether the calling device is at a known site. The telephony system thereafter distributes a telephone number for the calling device to use for the emergency call from a pool of telephone numbers selected based on that location. 
     The implementations of this disclosure describe using various network information detectable from a calling device to determine the region in which the calling device, and thus the operator of the calling device, is located. For example, information within an internet protocol (IP) space may be used to deduce location information from the network information to determine or approximate a city on the planet at which the calling device is. In some cases, an empirically updated internal record system that maps locations to call information may be used to determine the location of the calling device. Once the location of the calling device is determined, it is used to select one of a plurality of pools of telephone numbers which each correspond to a different region. A telephone number from the pool corresponding to the location of the calling device is distributed to the calling device for use in an emergency call. 
     To describe some implementations in greater detail, reference is first made to examples of hardware and software structures used to implement a system for location determination and telephone number distribution for emergency calls.  FIG.  1    is a block diagram of an example of an electronic computing and communications system  100 , which can be or include a distributed computing system (e.g., a client-server computing system), a cloud computing system, a clustered computing system, or the like. 
     The system  100  includes one or more customers, such as customers  102 A through  102 B, which may each be a public entity, private entity, or another corporate entity or individual that purchases or otherwise uses software services, such as of a UCaaS platform provider. Each customer can include one or more clients. For example, as shown and without limitation, the customer  102 A can include clients  104 A through  104 B, and the customer  102 B can include clients  104 C through  104 D. A customer can include a customer network or domain. For example, and without limitation, the clients  104 A through  104 B can be associated or communicate with a customer network or domain for the customer  102 A and the clients  104 C through  104 D can be associated or communicate with a customer network or domain for the customer  102 B. 
     A client, such as one of the clients  104 A through  104 D, may be or otherwise refer to one or both of a client device or a client application. Where a client is or refers to a client device, the client can comprise a computing system, which can include one or more computing devices, such as a mobile phone, a tablet computer, a laptop computer, a notebook computer, a desktop computer, or another suitable computing device or combination of computing devices. Where a client instead is or refers to a client application, the client can be an instance of software running on a customer device (e.g., a client device or another device). In some implementations, a client can be implemented as a single physical unit or as a combination of physical units. In some implementations, a single physical unit can include multiple clients. 
     The system  100  can include a number of customers and/or clients or can have a configuration of customers or clients different from that generally illustrated in  FIG.  1   . For example, and without limitation, the system  100  can include hundreds or thousands of customers, and at least some of the customers can include or be associated with a number of clients. 
     The system  100  includes a datacenter  106 , which may include one or more servers. The datacenter  106  can represent a geographic location, which can include a facility, where the one or more servers are located. The system  100  can include a number of datacenters and servers or can include a configuration of datacenters and servers different from that generally illustrated in  FIG.  1   . For example, and without limitation, the system  100  can include tens of datacenters, and at least some of the datacenters can include hundreds or another suitable number of servers. In some implementations, the datacenter  106  can be associated or communicate with one or more datacenter networks or domains, which can include domains other than the customer domains for the customers  102 A through  102 B. 
     The datacenter  106  includes servers used for implementing software services of a UCaaS platform. The datacenter  106  as generally illustrated includes an application server  108 , a database server  110 , and a telephony server  112 . The servers  108  through  112  can each be a computing system, which can include one or more computing devices, such as a desktop computer, a server computer, or another computer capable of operating as a server, or a combination thereof. A suitable number of each of the servers  108  through  112  can be implemented at the datacenter  106 . The UCaaS platform uses a multi-tenant architecture in which installations or instantiations of the servers  108  through  112  is shared amongst the customers  102 A through  102 B. 
     In some implementations, one or more of the servers  108  through  112  can be a non-hardware server implemented on a physical device, such as a hardware server. In some implementations, a combination of two or more of the application server  108 , the database server  110 , and the telephony server  112  can be implemented as a single hardware server or as a single non-hardware server implemented on a single hardware server. In some implementations, the datacenter  106  can include servers other than or in addition to the servers  108  through  112 , for example, a media server, a proxy server, or a web server. 
     The application server  108  runs web-based software services deliverable to a client, such as one of the clients  104 A through  104 D. As described above, the software services may be of a UCaaS platform. For example, the application server  108  can implement all or a portion of a UCaaS platform, including conferencing software, messaging software, and/or other intra-party or inter-party communications software. The application server  108  may, for example, be or include a unitary Java Virtual Machine (JVM). 
     In some implementations, the application server  108  can include an application node, which can be a process executed on the application server  108 . For example, and without limitation, the application node can be executed in order to deliver software services to a client, such as one of the clients  104 A through  104 D, as part of a software application. The application node can be implemented using processing threads, virtual machine instantiations, or other computing features of the application server  108 . In some such implementations, the application server  108  can include a suitable number of application nodes, depending upon a system load or other characteristics associated with the application server  108 . For example, and without limitation, the application server  108  can include two or more nodes forming a node cluster. In some such implementations, the application nodes implemented on a single application server  108  can run on different hardware servers. 
     The database server  110  stores, manages, or otherwise provides data for delivering software services of the application server  108  to a client, such as one of the clients  104 A through  104 D. In particular, the database server  110  may implement one or more databases, tables, or other information sources suitable for use with a software application implemented using the application server  108 . The database server  110  may include a data storage unit accessible by software executed on the application server  108 . A database implemented by the database server  110  may be a relational database management system (RDBMS), an object database, an XML database, a configuration management database (CMDB), a management information base (MIB), one or more flat files, other suitable non-transient storage mechanisms, or a combination thereof. The system  100  can include one or more database servers, in which each database server can include one, two, three, or another suitable number of databases configured as or comprising a suitable database type or combination thereof. 
     In some implementations, one or more databases, tables, other suitable information sources, or portions or combinations thereof may be stored, managed, or otherwise provided by one or more of the elements of the system  100  other than the database server  110 , for example, the client  104  or the application server  108 . 
     The telephony server  112  enables network-based telephony and web communications from and to clients of a customer, such as the clients  104 A through  104 B for the customer  102 A or the clients  104 C through  104 D for the customer  102 B. Some or all of the clients  104 A through  104 D may be voice over internet protocol (VOIP)-enabled devices configured to send and receive calls over a network  114 . In particular, the telephony server  112  includes a session initiation protocol (SIP) zone and a web zone. The SIP zone enables a client of a customer, such as the customer  102 A or  102 B, to send and receive calls over the network  114  using SIP requests and responses. The web zone integrates telephony data with the application server  108  to enable telephony-based traffic access to software services run by the application server  108 . Given the combined functionality of the SIP zone and the web zone, the telephony server  112  may be or include a cloud-based private branch exchange (PBX) system. 
     The SIP zone receives telephony traffic from a client of a customer and directs same to a destination device. The SIP zone may include one or more call switches for routing the telephony traffic. For example, to route a VOIP call from a first VOIP-enabled client of a customer to a second VOIP-enabled client of the same customer, the telephony server  112  may initiate a SIP transaction between a first client and the second client using a PBX for the customer. However, in another example, to route a VOIP call from a VOIP-enabled client of a customer to a client or non-client device (e.g., a desktop phone which is not configured for VOIP communication) which is not VOIP-enabled, the telephony server  112  may initiate a SIP transaction via a VOIP gateway that transmits the SIP signal to a public switched telephone network (PSTN) system for outbound communication to the non-VOIP-enabled client or non-client phone. Hence, the telephony server  112  may include a PSTN system and may in some cases access an external PSTN system. 
     The telephony server  112  includes one or more session border controllers (SBCs) for interfacing the SIP zone with one or more aspects external to the telephony server  112 . In particular, an SBC can act as an intermediary to transmit and receive SIP requests and responses between clients or non-client devices of a given customer with clients or non-client devices external to that customer. When incoming telephony traffic for delivery to a client of a customer, such as one of the clients  104 A through  104 D, originating from outside the telephony server  112  is received, a SBC receives the traffic and forwards it to a call switch for routing to the client. 
     In some implementations, the telephony server  112 , via the SIP zone, may enable one or more forms of peering to a carrier or customer premise. For example, Internet peering to a customer premise may be enabled to ease the migration of the customer from a legacy provider to a service provider operating the telephony server  112 . In another example, private peering to a customer premise may be enabled to leverage a private connection terminating at one end at the telephony server  112  and at the other end at a computing aspect of the customer environment. In yet another example, carrier peering may be enabled to leverage a connection of a peered carrier to the telephony server  112 . 
     In some such implementations, a SBC or telephony gateway within the customer environment may operate as an intermediary between the SBC of the telephony server  112  and a PSTN for a peered carrier. When an external SBC is first registered with the telephony server  112 , a call from a client can be routed through the SBC to a load balancer of the SIP zone, which directs the traffic to a call switch of the telephony server  112 . Thereafter, the SBC may be configured to communicate directly with the call switch. 
     The web zone receives telephony traffic from a client of a customer, via the SIP zone, and directs same to the application server  108  via one or more Domain Name System (DNS) resolutions. For example, a first DNS within the web zone may process a request received via the SIP zone and then deliver the processed request to a web service which connects to a second DNS at or otherwise associated with the application server  108 . Once the second DNS resolves the request, it is delivered to the destination service at the application server  108 . The web zone may also include a database for authenticating access to a software application for telephony traffic processed within the SIP zone, for example, a softphone. 
     The clients  104 A through  104 D communicate with the servers  108  through  112  of the datacenter  106  via the network  114 . The network  114  can be or include, for example, the Internet, a local area network (LAN), a wide area network (WAN), a virtual private network (VPN), or another public or private means of electronic computer communication capable of transferring data between a client and one or more servers. In some implementations, a client can connect to the network  114  via a communal connection point, link, or path, or using a distinct connection point, link, or path. For example, a connection point, link, or path can be wired, wireless, use other communications technologies, or a combination thereof. 
     The network  114 , the datacenter  106 , or another element, or combination of elements, of the system  100  can include network hardware such as routers, switches, other network devices, or combinations thereof. For example, the datacenter  106  can include a load balancer  116  for routing traffic from the network  114  to various servers associated with the datacenter  106 . The load balancer  116  can route, or direct, computing communications traffic, such as signals or messages, to respective elements of the datacenter  106 . For example, the load balancer  116  can operate as a proxy, or reverse proxy, for a service, such as a service provided to one or more remote clients, such as one or more of the clients  104 A through  104 D, by the application server  108 , the telephony server  112 , and/or another server. Routing functions of the load balancer  116  can be configured directly or via a DNS. The load balancer  116  can coordinate requests from remote clients and can simplify client access by masking the internal configuration of the datacenter  106  from the remote clients. 
     In some implementations, the load balancer  116  can operate as a firewall, allowing or preventing communications based on configuration settings. Although the load balancer  116  is depicted in  FIG.  1    as being within the datacenter  106 , in some implementations, the load balancer  116  can instead be located outside of the datacenter  106 , such as for global routing for multiple datacenters. In some implementations, load balancers can be included both within and outside of the datacenter  106 . In some implementations, the load balancer  116  can be omitted. 
       FIG.  2    is a block diagram of an example internal configuration of a computing device  200  of an electronic computing and communications system. In one configuration, the computing device  200  may implement one or more of the client  104 , the application server  108 , the database server  110 , or the telephony server  112  of the system  100  shown in  FIG.  1   . 
     The computing device  200  includes components or units, such as a processor  202 , a memory  204 , a bus  206 , a power source  208 , peripherals  210 , a user interface  212 , a network interface  214 , other suitable components, or a combination thereof. One or more of the memory  204 , the power source  208 , the peripherals  210 , the user interface  212 , or the network interface  214  can communicate with the processor  202  via the bus  206 . 
     The processor  202  is a central processing unit, such as a microprocessor, and can include single or multiple processors having single or multiple processing cores. Alternatively, the processor  202  can include another type of device, or multiple devices, configured for manipulating or processing information. For example, the processor  202  can include multiple processors interconnected in one or more manners, including hardwired or networked. The operations of the processor  202  can be distributed across multiple devices or units that can be coupled directly or across a local area or other suitable type of network. The processor  202  can include a cache, or cache memory, for local storage of operating data or instructions. 
     The memory  204  includes one or more memory components, which may each be volatile memory or non-volatile memory. For example, the volatile memory can be random access memory (RAM) (e.g., a DRAM module, such as DDR SDRAM). In another example, the non-volatile memory of the memory  204  can be a disk drive, a solid state drive, flash memory, or phase-change memory. In some implementations, the memory  204  can be distributed across multiple devices. For example, the memory  204  can include network-based memory or memory in multiple clients or servers performing the operations of those multiple devices. 
     The memory  204  can include data for immediate access by the processor  202 . For example, the memory  204  can include executable instructions  216 , application data  218 , and an operating system  220 . The executable instructions  216  can include one or more application programs, which can be loaded or copied, in whole or in part, from non-volatile memory to volatile memory to be executed by the processor  202 . For example, the executable instructions  216  can include instructions for performing some or all of the techniques of this disclosure. The application data  218  can include user data, database data (e.g., database catalogs or dictionaries), or the like. In some implementations, the application data  218  can include functional programs, such as a web browser, a web server, a database server, another program, or a combination thereof. The operating system  220  can be, for example, Microsoft Windows®, Mac OS X®, or Linux®, an operating system for a mobile device, such as a smartphone or tablet device; or an operating system for a non-mobile device, such as a mainframe computer. 
     The power source  208  provides power to the computing device  200 . For example, the power source  208  can be an interface to an external power distribution system. In another example, the power source  208  can be a battery, such as where the computing device  200  is a mobile device or is otherwise configured to operate independently of an external power distribution system. In some implementations, the computing device  200  may include or otherwise use multiple power sources. In some such implementations, the power source  208  can be a backup battery. 
     The peripherals  210  includes one or more sensors, detectors, or other devices configured for monitoring the computing device  200  or the environment around the computing device  200 . For example, the peripherals  210  can include a geolocation component, such as a global positioning system location unit. In another example, the peripherals can include a temperature sensor for measuring temperatures of components of the computing device  200 , such as the processor  202 . In some implementations, the computing device  200  can omit the peripherals  210 . 
     The user interface  212  includes one or more input interfaces and/or output interfaces. An input interface may, for example, be a positional input device, such as a mouse, touchpad, touchscreen, or the like; a keyboard; or another suitable human or machine interface device. An output interface may, for example, be a display, such as a liquid crystal display, a cathode-ray tube, a light emitting diode display, or other suitable display. 
     The network interface  214  provides a connection or link to a network (e.g., the network  114  shown in  FIG.  1   ). The network interface  214  can be a wired network interface or a wireless network interface. The computing device  200  can communicate with other devices via the network interface  214  using one or more network protocols, such as using Ethernet, transmission control protocol (TCP), internet protocol (IP), power line communication, an IEEE 802.X protocol (e.g., Wi-Fi, Bluetooth, or ZigBee), infrared, visible light, general packet radio service (GPRS), global system for mobile communications (GSM), code-division multiple access (CDMA), Z-Wave, another protocol, or a combination thereof. 
       FIG.  3    is a block diagram of an example of a software platform  300  implemented by an electronic computing and communications system, such as the system  100  shown in  FIG.  1   . The software platform  300  is a UCaaS platform accessible by clients of a customer of a UCaaS platform provider, such as the clients  104 A through  104 B of the customer  102 A or the clients  104 C through  104 D of the customer  102 B shown in  FIG.  1   . The software platform  300  may be a multi-tenant platform instantiated using one or more servers at one or more datacenters including, for example, the application server  108 , the database server  110 , and the telephony server  112  of the datacenter  106  shown in  FIG.  1   . 
     The software platform  300  includes software services accessible using one or more clients. For example, a customer  302  as shown includes four clients—a desk phone  304 , a computer  306 , a mobile device  308 , and a shared device  310 . The desk phone  304  is a desktop unit configured to at least send and receive calls and includes an input device for receiving a telephone number or extension to dial to and an output device for outputting audio and/or video for a call in progress. The computer  306  is a desktop, laptop, or tablet computer including an input device for receiving some form of user input and an output device for outputting information in an audio and/or visual format. The mobile device  308  is a smartphone, wearable device, or other mobile computing aspect including an input device for receiving some form of user input and an output device for outputting information in an audio and/or visual format. The desk phone  304 , the computer  306 , and the mobile device  308  may generally be considered personal devices configured for use by a single user. The shared device  310  is a desk phone, a computer, a mobile device, or a different device which may instead be configured for use by multiple specified or unspecified users. 
     Each of the clients  304  through  310  includes or runs on a computing device configured to access at least a portion of the software platform  300 . In some implementations, the customer  302  may include additional clients not shown. For example, the customer  302  may include multiple clients of one or more client types (e.g., multiple desk phones or multiple computers) and/or one or more clients of a client type not shown in  FIG.  3    (e.g., wearable devices or televisions other than as shared devices). In some such cases, the customer  302  may have tens or hundreds of desk phones, computers, mobile devices, and/or shared devices. 
     The software services of the software platform  300  generally relate to communications tools, but are in no way limited in scope. As shown, the software services of the software platform  300  include telephony software  312 , conferencing software  314 , messaging software  316 , and other software  318 . Some or all of the software  312  through  318  uses customer configurations  320  specific to the customer  302 . The customer configurations  320  may, for example, be data stored within a database or other data store at a database server, such as the database server  110  shown in  FIG.  1   . 
     The telephony software  312  enables telephony traffic between ones of the clients  304  through  310  and other telephony-enabled devices, which may be other ones of the clients  304  through  310 , other VOIP-enabled clients of the customer  302 , non-VOIP-enabled devices of the customer  302 , VOIP-enabled clients of another customer, non-VOIP-enabled devices of another customer, or other VOIP-enabled clients or non-VOIP-enabled devices. Calls sent or received using the telephony software  312  may, for example, be sent or received using the desk phone  304 , a softphone running on the computer  306 , a mobile application running on the mobile device  308 , or using the shared device  310  that includes telephony features. 
     The telephony software  312  further enables phones that do not include a client application to connect to other software services of the software platform  300 . For example, the telephony software  312  may receive and process calls from phones not associated with the customer  302  to route that telephony traffic to one or more of the conferencing software  314 , the messaging software  316 , or the other software  318 . 
     The conferencing software  314  enables audio, video, and/or other forms of conferences between multiple participants, such as to facilitate a conference between those participants. In some cases, the participants may all be physically present within a single location, for example, a conference room, in which the conferencing software  314  may facilitate a conference between only those participants and using one or more clients within the conference room. In some cases, one or more participants may be physically present within a single location and one or more other participants may be remote, in which the conferencing software  314  may facilitate a conference between all of those participants using one or more clients within the conference room and one or more remote clients. In some cases, the participants may all be remote, in which the conferencing software  314  may facilitate a conference between the participants using different clients for the participants. The conferencing software  314  can include functionality for hosting, presenting scheduling, joining, or otherwise participating in a conference. The conferencing software  314  may further include functionality for recording some or all of a conference and/or documenting a transcript for the conference. 
     The messaging software  316  enables instant messaging, unified messaging, and other types of messaging communications between multiple devices, such as to facilitate a chat or other virtual conversation between users of those devices. The unified messaging functionality of the messaging software  316  may, for example, refer to email messaging which includes a voicemail transcription service delivered in email format. 
     The other software  318  enables other functionality of the software platform  300 . Examples of the other software  318  include, but are not limited to, device management software, resource provisioning and deployment software, administrative software, third party integration software, and the like. In one particular example, the other software  318  can include emergency calling software for detecting a location of a calling device and distributing a telephone number from a telephone number pool associated with that determined location to the calling device to facilitate a call between the calling device and a local PSAP. 
     The software  312  through  318  may be implemented using one or more servers, for example, of a datacenter such as the datacenter  106  shown in  FIG.  1   . For example, one or more of the software  312  through  318  may be implemented using an application server, a database server, and/or a telephony server, such as the servers  108  through  112  shown in  FIG.  1   . In another example, one or more of the software  312  through  318  may be implemented using servers not shown in  FIG.  1   , for example, a meeting server, a web server, or another server. In yet another example, one or more of the software  312  through  318  may be implemented using one or more of the servers  108  through  112  and one or more other servers. The software  312  through  318  may be implemented by different servers or by the same server. 
     Features of the software services of the software platform  300  may be integrated with one another to provide a unified experience for users. For example, the messaging software  316  may include a user interface element configured to initiate a call with another user of the customer  302 . In another example, the telephony software  312  may include functionality for elevating a telephone call to a conference. In yet another example, the conferencing software  314  may include functionality for sending and receiving instant messages between participants and/or other users of the customer  302 . In yet another example, the conferencing software  314  may include functionality for file sharing between participants and/or other users of the customer  302 . In some implementations, some or all of the software  312  through  318  may be combined into a single software application run on clients of the customer, such as one or more of the clients  304  through  310 . 
       FIG.  4    is a block diagram of an example of a system for location determination and telephone number distribution for emergency calls. The system includes a telephony system  400 , which includes hardware and/or software for facilitating telephony communications. For example, the telephony system  400  may be or include the telephony server  112  shown in  FIG.  1    and/or may run or implement the telephony software  312  shown in  FIG.  3   . In particular, the telephony system  400  facilitates inbound calls to and outbound calls from a calling device  402 . In a specific example, the telephony system  400  facilitates outbound calls from the calling device  402  to a PSAP  404  and/or inbound calls from the PSAP  404  to the calling device  402 . 
     The calling device  402  is a device configured to make telephone calls, for example, a desk phone device, a mobile phone device, or a device running a softphone. In some implementations, the calling device  402  may be a client device, for example, one of the clients  304  through  310  shown in  FIG.  3   , which runs a client application. The client application may be client-side software for connecting to services of a UCaaS platform, such as the UCaaS platform  300  shown in  FIG.  3   . 
     The PSAP  404  includes representatives who field emergency (e.g.,  911  or  111 ) calls and dispatch emergency responders to the locations of subject emergency events. Agents of the PSAP  404  confirm locations of those emergency events before coordinating with emergency responders. In some cases, where the region in which the PSAP  404  is located supports enhanced emergency service infrastructure such as E911 services, the PSAP  404  may be configured to receive information indicating the location of a device from which an emergency call to the PSAP  404  is placed such as to assist in confirming the location of an emergency event. 
     The telephony system  400  includes emergency calling software  406  and call processing components  408 . The telephony system  400 , using the emergency calling software  406  and the call processing components  408 , is configured to determine a location of the calling device  402  responsive to the calling device  402  initiating an emergency call to the PSAP  404  and to thereafter facilitate a call between the calling device  402  and the PSAP  404  by distributing a telephone number usable to connect with the PSAP  404  to the calling device  402  based on the determined location of the calling device  402 . 
     In particular, the emergency calling software  406  receives an indication that the calling device  402  has initiated an emergency call process and then determines a location of the calling device  402 . The emergency call process may be initiated by an operator of the calling device  402  attempting to dial an emergency number local to the region in which the calling device  402  is located (e.g., 911 for the United States or 111 for New Zealand), in which a client application running at the calling device  402  can detect that the emergency number has been dialed at the calling device  402  and signal information indicative of that detection to the emergency calling software  406 . In another example, the operator of the calling device  402  may initiate the emergency call process within the client application itself, in which the client application may signal information indicative of that initiation to the emergency calling software  406 . 
     The emergency calling software  406 , responsive to detecting the initiation of the emergency call process, determines the location of the calling device  402 . In particular, the emergency calling software  406  determines or approximates a region in which the calling device  402  is located. A region may refer to a country, a territory, or a group of countries or territories (e.g., the United Kingdom, the European Union, North America, or Southeast Asia). The emergency calling software  406 , which has access to multiple pools of telephone numbers each corresponding to a different region, then selects one of those pools of telephone numbers based on the determined location of the calling device  402 . For example, the emergency calling software  406  may match the region corresponding to the determined location of the calling device  402  with a pool of telephone numbers corresponding to that same region. Once the pool of telephone numbers is selected, the emergency calling software  406  distributes a telephone number from that pool to the calling device  402 . 
     The calling processing components  408  include one or more telephony aspects described with respect to the telephony server  112  shown in  FIG.  1   , such as telephony aspects of a SIP zone and/or telephony aspects of a web zone, for facilitating calls between endpoints, such as the calling device  402  and the PSAP  404 . In particular, once emergency calling software  406  has distributed the telephone number to the calling device  402 , the call processing component  408  facilitate a telephone call between the calling device  402  and the PSAP  404  based on that telephone number. In some implementations, the call processing components  408  may facilitate multiple calls between the calling device  402  and the PSAP  404  based on the distributed telephone number, such as after an initial call from the calling device  402  to the PSAP  404 . 
     In some implementations, the emergency calling software  406  or a portion thereof may be run at the calling device  402  rather than at the telephony system  400 . For example, a client application running on the calling device  402  may include all or a portion of the emergency calling software  406 . In some such implementations, the client application, using the emergency calling software  406  or the portion thereof, may interface with software running at the telephony system  400  to cause a selection of a pool of telephone numbers, cause a distribution of a telephone number from that pool to the calling device  402 , and/or cause other operations of the emergency calling software  406  to be performed. 
       FIG.  5    is a block diagram of examples of telephone number pools associated with different regions. As described above, a system for location determination and telephone number distribution for emergency calls as disclosed herein includes emergency calling software, for example, the emergency calling software  406  shown in  FIG.  4   , which determines a location of a calling device, for example, the calling device  402  shown in  FIG.  4   , from which an emergency call is to be made and distributes a telephone number to that calling device from a pool of telephone numbers corresponding to that determined location of the calling device. 
     Thus, the location of the calling device is determined to be one of a plurality of potential regions and the pool of telephone numbers is determined to be one of a plurality of pools of telephone numbers. Accordingly, and as illustrated in  FIG.  5   , the regions within which a calling device may be determined to be located may be one of a region 1  500  which includes a PSAP 1  502  through a region N  504  which includes a PSAP  506 , in which the value of N is an integer greater than 1. Although a single PSAP is shown in each of the region 1  500  through the region N  504 , there may be other numbers of PSAP in one or more such region. 
     A telephony system  508 , which may, for example, be the telephony system  400  shown in  FIG.  4   , maintains multiple pools of telephone numbers including a telephone number pool 1  510  through a telephone number pool N  512  in which the value of N again is an integer greater than 1. Each of the telephone number pools 1  510  through N  512  corresponds to one region of the regions 1  500  through N  504 . The mappings between ones of the telephone number pools 1  510  through N  512  to ones of the regions 1  500  through N  504  may be defined at or by the telephone system  508 . The telephone numbers in a given pool of telephone numbers are usable to make calls, including emergency calls, within the corresponding region. 
     In the example shown, the telephone number pool 1  510  corresponds to the region 1  500  and the telephone number pool N  512  corresponds to the region N  504 . As such, where a calling device is determined to be located in the region 1  500  when the telephony system  508  detects that an emergency call process is being initiated at the calling device, the telephony system  508  will select the telephone number pool 1  510  from amongst the multiple pools of telephone numbers and thereafter distribute a telephone number from the telephone number pool 1  510  to the calling device. 
     The distribution of telephone numbers from a given pool of telephone numbers to a calling device is temporary to ensure a pool of telephone numbers is not empty for a prolonged period of time. A telephone number distributed to a calling device from a pool of telephone numbers corresponding to a given region may not be used in a different region. For example, as shown by the severed, dashed connection between the PSAP N  506  in the region N  504  and the telephone number pool 1  510 , a telephone number distributed from the telephone number pool 1  510  may not be usable to make calls, such as emergency calls, within the region N  504 , such as to the PSAP N  506 . 
       FIG.  6    is a block diagram of example functionality of emergency calling software  600 . The emergency calling software  600  may, for example, be the emergency calling software  406  shown in  FIG.  4   . The emergency calling software  600  includes tools, such as programs, subprograms, functions, routines, subroutines, operations, and/or the like, for detecting a location of a calling device and distributing a telephone number from a telephone number pool associated with that determined location to the calling device to facilitate a call between the calling device and a local PSAP. As shown, the emergency calling software  600  includes an emergency call detection tool  602 , a location determination tool  604 , a telephone number pool selection tool  606 , a number distribution tool  608 , and an internal record update tool  610 . 
     The emergency call detection tool  602  detects that an emergency call process has been initiated at a calling device. The emergency call detection tool  602  detects that the emergency call process has been initiated using a client application running at the calling device. For example, the emergency call detection tool  602  may listen to the client application. In another example, the client application may push information to the emergency call detection tool  602 . The emergency call process is initiated by an operator of the calling device attempting to dial an emergency number local to the region in which the calling device is located, in which the client application can detect that the emergency number has been dialed at the calling device. In another example, the operator of the calling device  402  may initiate the emergency call process within the client application itself. In either case, the client application can signal an indication of that detection or initiation to the emergency call detection tool  602 . Alternatively, in either case, the emergency call detection tool  602  can pull information indicative of that detection or initiation from the client application. 
     The location determination tool  604  determines a region in which the calling device is located. In particular, the location determination tool  604  determines a region in which the calling device is located in response to the emergency call detection tool  602  detecting that the emergency call process has been initiated at the calling device. The region in which the calling device is located is primarily determined based on a city in which the calling device is located. In some cases, the location determination tool  604  uses geolocation information obtained by the client application accessing a geolocation sensor (e.g., a geospatial positioning system (GPS) component) onboard the calling device to determine a location of the calling device. In some cases, the obtained geolocation information identifies at least a city in which the calling device is located. In other such cases, where the obtained geolocation information does not specify a street address or city information, such as where the geolocation information is expressed in coordinate format, the location determination tool  604  can on its own or using another software aspect use an application programming interface (API) call to a mapping application to obtain the street address or city information associated therewith. 
     In other cases, whether or not the client application has been granted permission to access the geolocation sensor of the calling device, the location determination tool  604  may determine the location of the calling device based on network information obtained by the calling device. The network information indicates one or more networks within some physical range of the calling device. The one or more networks may include public or private Wi-Fi networks, Bluetooth networks, and/or other networks to which a computing device could connect. The network information may in some cases also identify one or more devices which are connected to the network, such as by a public IP address and/or a subnet or private IP address for operator devices; a MAC address, port label, and/or port range of a network switch; and a basic service set identifier (BSSID) of a wireless access point. 
     The location determination tool  604  can cross-reference those identified networks and/or devices against an internal record system. The internal record system includes a data store storing records of verifications of addresses and/or other location information associated with networks and/or deices. Where the data store of the internal record system includes an entry corresponding to an identified network or device, an address thereof can be retrieved from the data store. The location determination tool  604 , given that the calling device is in a detectable range of the network or device, thus determines the location of the calling device based on the address retrieved from the data store of the internal record system. 
     Where the data store of the internal record system does not include an entry corresponding to any of the identified networks or devices, the location determination tool  604  may push a new record therein for such a network or device including address information associated with geolocation information obtained from the geolocation component of the calling device. Where geolocation access has not been granted to the client application, the location determination tool  604 , either itself or using another software aspect, may use a public API source to query for a location of the calling device and then push a new record within the data store of the internal record system for an identified network or device based on address information associated with that location. 
     The location determination tool  604  determines the location of the calling device with as much specificity as possible to ensure accuracy. In particular, where it can be determined, the location will be expressed as a street address along with city, state/providence, and country/territory information. In some cases, the location may further be expressed more granularly such as using floor, room, office, and/or other identifiers in a building with a single street address. However, in some cases where a street address cannot be verified using the detected network information and/or internal records, the location may be approximated to a specific city. This is because the location determination tool  604  is used to determine a region within which the calling device is located, in which, as will be described below, the region is used to select a pool of telephone numbers from which to distribute a telephone number suitable for the region to the calling device. 
     The telephone number pool selection tool  606  selects a pool of telephone numbers from which to distribute a telephone number to the calling device. The telephone number pool selection tool  606  has access to a plurality of pools of telephone numbers maintained by a service provider (e.g., the service provider implementing some or all of the telephony system  400  shown in  FIG.  4   ) in which each of the pools of telephone numbers is associated with a different region. The location determined by the location determination tool  604 , whether expressed granularly based on a street address or further detail or on a more macro-level such as based on a city, indicates the region (e.g., the country or territory) in which the calling device is located. Accordingly, the telephone number pool selection tool  606  uses the location information determined by the location determination tool  604  by comparing a region associated therewith against the regions associated with the various pools of telephone numbers until a match is found. The selected pool of telephone numbers is thus the pool of telephone numbers which is associated with the region in which the calling device is determined to be located. 
     The number distribution tool  608  distributes a telephone number from the selected pool of telephone numbers to the calling device. The telephone number is configured for use in the region associated with the selected pool of telephone numbers. The number distribution tool  608  distributes the telephone number by removing the telephone number from the selected pool of telephone numbers to prevent it from being concurrently used by another device and by pushing a configuration to the calling device to enable the calling device to use the telephone number for one or more calls, such as the emergency call with the PSAP. 
     The telephone number which is distributed is selected from amongst the telephone numbers of the selected pool of telephone numbers. The number distribution tool  608  may use one or more techniques for selecting the telephone number to distribute. In some cases, the telephone numbers may be ordered in the pool according to a stack or queue structure, in which case the distributed telephone number is selected based on it being the next telephone number in the subject order (e.g., first-in-first-out or first-in-last-out). In some cases, the telephone number is selected at random from amongst the telephone numbers in the pool. Other examples for selecting the telephone number are also possible. 
     The internal record update tool  610  optionally updates the internal record system which may in some cases be used by the location determination tool  604  to determine the location of the calling device. As described above, the internal record system includes a data store which stores records indicative of location information of known networks and/or devices based on information obtained during one or more emergency call processes with calling devices. Over time, the internal record system becomes large based on new records being generated and stored such that the internal record system may in at least some cases be used to improve the determination of a calling device location and thus enable faster emergency calling using distributed telephone numbers. 
     However, in some cases, network information previously obtained and stored in a record of the internal record system data store may change or otherwise become out of date. For example, network devices may be moved, networks may be renamed or terminated, devices may be replaced with new devices, and so on. In such a case, outdated network information currently stored in the internal record system should be updated to prevent it from being used to determine the location of a calling device. Accordingly, the internal record update tool  610  may increase the accuracy of the internal record system by using the network information and address information obtained as part of the emergency call process for a calling device to determine whether information stored in a record of the internal record system is incorrect. Upon determining that such a record is incorrect, the internal record update tool  610  may update or delete that record. 
     In some implementations, the emergency calling software  600  may include other tools in addition to and/or instead of the tools  602  through  610 . Although the tools  602  through  610  are shown as functionality of the emergency calling software  600  as a single piece of software, in some implementations, some or all of the tools  602  through  610  may exist outside of the emergency calling software  600  and/or the software platform may exclude the emergency calling software  600  while still including the some or all of tools  602  through  610  in some form elsewhere. For example, in some implementations, some or all of the tools  602  through  610  may be included in a client application running at a calling device, for example, the calling device  402  shown in  FIG.  4   . In some implementations, one or more of the tools  602  through  610  may be omitted. 
       FIG.  7    is a block diagram of an example of a telephony system  700  which determines a location of a calling device  702  and distributes a telephone number to the calling device  702 . The telephony system  700  and the calling device  702  may, for example, respectively be the telephony system  400  and the calling device  402  shown in  FIG.  4   . The telephony system  700  includes various hardware and/or software components for facilitating the determination of the location of the calling device  702  and the distribution of the telephone number to the calling device  702 . As shown, the telephony system  700  includes an emergency call detection tool  704 , a location determination tool  706 , a telephone number pool selection tool  708 , and a number distribution tool  710 , which may, for example, be the tools  602  through  608  shown in  FIG.  6   . The telephony system  700  further includes various hardware and/or software components for facilitating a telephone call between the calling device  702  and a PSAP  712 , such as call processing components  714 , which may, for example, be the call processing components  408  shown in  FIG.  4   . 
     The emergency call detection tool  704  detects when an operator of the calling device  702  initiates an emergency call process. In response thereto, the location determination tool  706  determines a location of the calling device  702 . For example, the location determination tool  706  may use records  716  stored within a data store of an internal record system to determine the location of the calling device  702 . The telephone number pool selection tool  708  thereafter determines a pool of telephone numbers from which a telephone number is to be distributed to the calling device  702  from amongst a plurality of pools of telephone numbers  718  maintained at the telephony system  700 , such as by a service provider associated with (e.g., operating) the telephony system  700 . Once the pool of telephone numbers is selected based on the location of the calling device  702 , the number distribution tool  710  distributes a telephone number from that pool to the calling device  702 . The telephony system  700  then, using the call processing components  714 , facilitates an emergency call between the calling device  702  and the PSAP  712 . 
     In particular, the emergency call includes an outbound call from the calling device  702  to the PSAP  712  based on the telephone number. However, in some cases, the emergency call may further include an inbound call from the PSAP  712  to the calling device  702  by the PSAP  712  calling back to the telephone number. For example, the PSAP  712  may log the telephone number used by the calling device  702  to call the PSAP  712 . In the event an agent at the PSAP  712  needs to reach the operator of the calling device  702 , such as to collect further information about an emergency event or for other purposes, the telephony system  700  may facilitate, using the call processing components  714 , a call from the PSAP  712  to the calling device  702 . 
     In some implementations, a temporary routing rule may be defined to configure the telephone number for use in making outbound calls from the calling device  702  and/or receiving inbound calls at the calling device  702 . For example, the number distribution tool  710  or another tool of the telephony system  700  may generate a temporary routing rule to temporarily link the distributed telephone number with the calling device  702  until the emergency call is concluded. The conclusion of the emergency call may be determined in one or more ways. For example, the operator of the calling device  702  may indicate the conclusion of the emergency call at the calling device  702  in response to a prompt from the telephony system  700 . In another example, the conclusion of the emergency call may be inferred based on a threshold period of time (e.g., one hour) which has elapsed since the telephone number was distributed to the calling device  702 . In yet another example, the conclusion of the emergency call may be determined based on an event, such as an emergency responder arriving at the scene of the emergency event for which the emergency call process was initiated at the calling device  702 . 
     In some implementations, location information associated with the calling device  702  may be signaled to the PSAP  712  concurrently with or otherwise within the emergency call facilitated by the telephony system  700  between the calling device  702  and the PSAP  712 . For example, and based on the region in which the PSAP  712  is located, the PSAP  712  may or may not support enhanced emergency calling services, such as using E911 in the United States. With enhanced emergency calling, location information may be digitally transmitted as part of an emergency call from the calling device  702  to the PSAP  712 , either by the calling device  702  integrating that location information within the call or by an intermediary aspect (e.g., the telephony system  700 ) intercepting the call coming from the calling device  702  and integrating the location information before forwarding it to the SPAP  712 . 
     In another example, where the PSAP  712  does not support such enhanced emergency calling services and the location determination tool  706  determined a street address for the calling device  702 , the telephony system  700  can transmit data configured to cause a public database usable by the PSAP  712  to update with the caller ID record associated with the distributed telephone number with that street address information, such as based on an API call while the emergency call is in transit. In this way, the agent at the PSAP  712 , upon searching that public database, may identify the updated address information. Alternatively, where the PSAP  712  does not support such enhanced emergency calling services and the location determination tool  706  determined a location but not a specific street address, the telephony system  700  can transmit data configured to cause the public database usable by the PSAP  712  to list information associated with the caller ID record associated with the distributed telephone number saying that the address of record is unknown and to confirm that address with the caller. 
     To further describe some implementations in greater detail, reference is next made to examples of techniques which may be performed by or using a system for location determination and telephone number distribution for emergency calls.  FIG.  8    is a flowchart of an example of a technique  800  for location determination and telephone number distribution for emergency calls.  FIG.  9    is a flowchart of an example of a technique  900  for determining a location of a calling device.  FIG.  10    is a flowchart of an example of a technique  1000  for facilitating calls between a calling device and a PSAP. 
     The technique  800 , the technique  900 , and/or the technique  1000  can be executed using computing devices, such as the systems, hardware, and software described with respect to  FIGS.  1 - 7   . The technique  800 , the technique  900 , and/or the technique  1000  can be performed, for example, by executing a machine-readable program or other computer-executable instructions, such as routines, instructions, programs, or other code. The steps, or operations, of the technique  800 , the technique  900 , and/or the technique  1000  or another technique, method, process, or algorithm described in connection with the implementations disclosed herein can be implemented directly in hardware, firmware, software executed by hardware, circuitry, or a combination thereof. 
     For simplicity of explanation, the technique  800 , the technique  900 , and the technique  1000  are each depicted and described herein as a series of steps or operations. However, the steps or operations in accordance with this disclosure can occur in various orders and/or concurrently. Additionally, other steps or operations not presented and described herein may be used. Furthermore, not all illustrated steps or operations may be required to implement a technique in accordance with the disclosed subject matter. 
     Referring first to  FIG.  8   , the technique  800  for location determination and telephone number distribution for emergency calls is shown. At  802 , a location of a calling device is determined. The location of the calling device is determined responsive to an operator of the calling device initiating an emergency call to a PSAP. For example, the initiation of the emergency call can be determined using a client application running at the calling device. Determining the location of the calling device includes determining a candidate location of the calling device based on network information within a detectable range of the calling device and then comparing that candidate location against records of locations within a data store of an internal record system to determine the candidate location is accurate. 
     At  804 , a pool of telephone numbers associated with the location of the calling device is determined. The pool of telephone numbers is one of a plurality of pools of telephone numbers maintained by a telephony service provider. Each pool of telephone numbers of the plurality of pools of telephone numbers is associated with a different region. Determining the pool of telephone numbers associated with the location of the calling device includes selecting the pool of telephone numbers from the plurality of pools of telephone numbers based on a determination that the location of the calling device is associated with a region with which that selected pool is also associated. In particular, the region with which the selected pool of telephone numbers is associated is different from a region associated with a telephone extension configured for use with the calling device. For example, the pool of telephone numbers and the local PSAP to be called may both be associated with a first region and the telephone extension configured for use with the calling device may be associated with a second region. 
     At  806 , a telephone number is distributed from the pool of telephone numbers to the calling device for use with the emergency call. For example, distributing the telephone number from the pool of telephone numbers may include removing the telephone number from the pool of telephone numbers. In another example, distributing the telephone number from the pool of telephone numbers may include indicating an in-use status of the telephone number within a record associated with the pool of telephone numbers. In some implementations, distributing the telephone number to the calling device can include generating and asserting a temporary routing rule associating the telephone number and the calling device for one or more outbound and/or inbound calls associated with the emergency call. 
     At  808 , the emergency call is facilitated between the calling device and a local PSAP based on the telephone number. The emergency call may be or include one or more outbound calls from the calling device to the PSAP and/or one or more inbound calls from the PSAP to the calling device. The emergency call is facilitated using call processing components of a telephony system. Thus, in some cases, the distribution of the telephone number to the calling device for use with the emergency call enables a callback to the calling device from the PSAP based on the telephone number. 
     In some implementations, such as where the PSAP supports enhanced emergency services, facilitating the emergency call between the calling device and the PSAP based on the telephone number may include associating the location of the calling device with the telephone number to cause the calling device to signal the location of the calling device to the public safety answering point within the emergency call. In some implementations, such as where the PSAP does not support enhanced emergency services, the technique  800  may include updating a local public database accessible by the PSAP to indicate an unknown location of the calling device. 
     At  810 , the distributed telephone number is returned to the pool of telephone numbers from which it was distributed. For example, the distributed telephone number may be returned to the pool of telephone numbers in response to a conclusion of the emergency call. 
     Referring next to  FIG.  9   , the technique  900  for determining a location of a calling device is shown. At  902 , network information in range of the calling device is detected. The network information may correspond to one or more networks and/or one or more devices within a detectable range of the calling device. The detectable range may be defined as a physical space surrounding the calling device within which the calling device is capable of detecting a network or detecting that a device is connected to a network. The network information may include one or more Wi-Fi networks, one or more Bluetooth networks, and/or one or more other networks detectable by the calling device and/or one or more devices connected to one or more such networks. 
     At  904 , a candidate location of the calling device is determined based on the network information. For example, address information may be determined for one or more of the networks and/or devices associated with the network information. That address information may be expressed as a street address or on a larger scale, such as at the city-level. 
     At  906 , the candidate location is compared against records of an internal record system to determine a location of the calling device. The internal record system includes a data store which stores records indicating locations of various previously identified networks and/or devices. Comparing the candidate location against the records of the internal record system includes searching through the records of the data store for a location matching the candidate location. Upon such a match, the location of the calling device is determined as the location associated with the subject record. 
     At  908 , optionally, one or more records of the internal record system may be updated. For example, responsive to determining that the address of the calling device is different from the address determined based on a record of the internal record system, such as based on input received from the operator of the calling device, a transcription of the emergency call between the calling device and the PSAP, or another source, that record may be updated based on such input to replace the previously stored location information associated with that record. 
     Referring finally to  FIG.  10   , the technique  1000  for facilitating calls between a calling device and a PSAP is shown. At  1002 , a temporary routing rule associating a distributed telephone number and a calling device is asserted. The temporary routing rule may be generated responsive to or prior to the distribution of the telephone number to the calling device. Asserting the temporary routing rule includes pushing configurations to cause one or more outbound calls from and/or one or more inbound calls to the telephone number to be routed to the calling device. 
     At  1004 , an outbound call from the calling device to a local PSAP is facilitated based on the temporary routing rule. At  1006 , optionally, an inbound call from the local PSAP to the calling device may be facilitated based on the temporary routing rule. In some implementations, a further outbound call and/or a further inbound call may also be facilitated between the calling device and the PSAP. 
     At  1008 , the temporary routing rule is revoked. The temporary routing rule is revoked responsive to the telephone number being returned to the pool of telephone numbers. The telephone number is returned to the pool of telephone numbers upon the conclusion of the emergency call between the calling device and the PSAP. Revoking the temporary routing rule includes deleting a record associating the telephone number with the calling device to prevent further inbound calls to or outbound calls from the calling device based on the telephone number without the telephone number being redistributed to the calling device. 
     The implementations of this disclosure can be described in terms of functional block components and various processing operations. Such functional block components can be realized by a number of hardware or software components that perform the specified functions. For example, the disclosed implementations can employ various integrated circuit components (e.g., memory elements, processing elements, logic elements, look-up tables, and the like), which can carry out a variety of functions under the control of one or more microprocessors or other control devices. Similarly, where the elements of the disclosed implementations are implemented using software programming or software elements, the systems and techniques can be implemented with a programming or scripting language, such as C, C++, Java, JavaScript, assembler, or the like, with the various algorithms being implemented with a combination of data structures, objects, processes, routines, or other programming elements. 
     Functional aspects can be implemented in algorithms that execute on one or more processors. Furthermore, the implementations of the systems and techniques disclosed herein could employ a number of conventional techniques for electronics configuration, signal processing or control, data processing, and the like. The words “mechanism” and “component” are used broadly and are not limited to mechanical or physical implementations, but can include software routines in conjunction with processors, etc. Likewise, the terms “system” or “tool” as used herein and in the figures, but in any event based on their context, may be understood as corresponding to a functional unit implemented using software, hardware (e.g., an integrated circuit, such as an ASIC), or a combination of software and hardware. In certain contexts, such systems or mechanisms may be understood to be a processor-implemented software system or processor-implemented software mechanism that is part of or callable by an executable program, which may itself be wholly or partly composed of such linked systems or mechanisms. 
     Implementations or portions of implementations of the above disclosure can take the form of a computer program product accessible from, for example, a computer-usable or computer-readable medium. A computer-usable or computer-readable medium can be a device that can, for example, tangibly contain, store, communicate, or transport a program or data structure for use by or in connection with a processor. The medium can be, for example, an electronic, magnetic, optical, electromagnetic, or semiconductor device. 
     Other suitable mediums are also available. Such computer-usable or computer-readable media can be referred to as non-transitory memory or media, and can include volatile memory or non-volatile memory that can change over time. The quality of memory or media being non-transitory refers to such memory or media storing data for some period of time or otherwise based on device power or a device power cycle. A memory of an apparatus described herein, unless otherwise specified, does not have to be physically contained by the apparatus, but is one that can be accessed remotely by the apparatus, and does not have to be contiguous with other memory that might be physically contained by the apparatus. 
     While the disclosure has been described in connection with certain implementations, it is to be understood that the disclosure is not to be limited to the disclosed implementations but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.