Abstract:
Methods and systems for obtaining the location of a caller during an emergency or other telephone call. Before or during a call, a phone system can obtain from one or more sources a subscriber access line identity associated with a subscriber location record that includes a subscriber access line identity attribute and a subscriber location attribute. A phone system can send a query that includes the subscriber access line identity to a subscriber location query system that returns a subscriber location record or a subscriber location to the phone system. The phone system can then display the caller location information to a phone system, an agent or operator so that emergency services can be quickly and accurately dispatched. Using similar procedure and a memory, phone systems can also determine if a subscriber phone has or is changing location. Methods for testing the emergency call capabilities of a subscriber access line.

Description:
BACKGROUND 
   1. Field 
   This invention relates generally to telecommunications, more specifically, to a method and system to provide location information for voice calls. 
   2. Related Art 
   Around the world there are many emergency telephone numbers. For example, in the United States of America, the three-digit telephone number “911” is designated as the universal emergency telephone number. In the case of an emergency, a person can call 911 to reach an operator who can dispatch appropriate emergency services. To help provide the timeliest response, it is helpful and often necessary to have the location of the caller reported to the emergency service dispatcher. This is feature is of utmost importance when the caller is a young child, someone who is very ill or injured or otherwise unable to effectively communicate their location to the emergency services dispatcher. For these services to function properly, the telephone service provider must have means of identifying and reporting the location of the emergency caller. 
   In a typical scenario, when a subscriber subscribes to a residential telephone service from a service provider, the service provider assigns a telephone number for that subscription and allocates an access line to the subscriber&#39;s residence for the service. The access line connects to a telephone system of the residential telephone service. A user connects a telephone to the access line and uses the telephone to receive the residential telephone service. 
   The location of the subscription is the connecting point of the access line and the telephone. The location is typically the street address of the subscriber&#39;s residence. The service provider submits the telephone number and the location of the subscription to create a record in an Automatic Location identity (ALI) database. The record maps the telephone number to the location of the subscription. One of the usages of ALI database is for Emergency call purpose. 
   When a caller uses the telephone to make an emergency call by dialing “911”, the telephone system determines the telephone number associated with the subscription. The telephone system sends a call request to a 911 selective router telephone system. The call request includes the telephone number. 
   The 911-selective router telephone system receives the telephone number in the call request and retrieves from the ALI database the location of the subscription based on the telephone number. The location is presumably where the caller of the emergency call is. The 911-selective router telephone system uses the location to select a Public Safety Answering Point (PSAP), which is a telephone system. The 911-selective router telephone system further sends the emergency call request to the PSAP. The call request also includes the telephone number. 
   The PSAP presents the emergency call to an emergency call agent. The PSAP also retrieves from the ALI database the location of the subscription based on the telephone number in the emergency call request, and informs the emergency call agent of the location from which the call originated. The agent uses the location to dispatch emergency personnel and services. 
   Recently, various service providers have been rolling out new telephone services. These telephone services include cellular telephone services, and Voice over IP (VoIP) telephone services. Although these telephone services are not the same as traditional residential telephone services, they are either marketed as residential telephone services or subscribers use them as if they are equivalent to residential telephone services. Many consumers mistakenly assume that 911 or emergency services will be available in these new telephone services as they are in traditional residential telephone services. However this is often not the case. Cellular and VoIP telephone services, due to their ability to move from one physical location to another, present a fairly complex problem when it come to providing emergency call services. Especially when those services are highly dependent on knowing from whence the emergency call is being made. 
   In the case of VoIP telephone service, a user receives VoIP telephone service by connecting an IP telephone to a VoIP telephone system via the Internet. In one scenario, the IP telephone may be connected to a home DSL broadband Internet access gateway. It is also possible to connect the same IP telephone to a neighbor&#39;s Cable Modem broadband Internet access gateway. As a further convenience, is it also possible to connect an IP telephone to the IP network of a hotel during an out-of-town trip. In each example, the IP telephone is used to receive VoIP telephone service. While the convenience of being able to travel to any location with an appropriate Internet access, there is a danger associated with assuming that emergency services will be available on the IP telephone as on a regular telephone. To illustrate this danger, consider the following scenario. 
   While out of town, a user has an accident or encounters an emergency. The user calls 911 on an IP telephone that they have brought from home. The user assumes the 911-emergency call center would know her location, and expects emergency services to arrive in a short period of time. When the emergency call is not answered or when emergency services do not arrive in an hour, the user panics. Whilst in the hotel, the user&#39;s spouse calls the user&#39;s IP telephone number from their home concerned that emergency services were dispatched to their home for her whilst she is away. From the IP telephone service, the emergency dispatch services had no way of knowing her location. 
   As shown in the new telephone services, there is a need for a fundamentally new solution to provide the correct location of a caller during an emergency call. 
   SUMMARY 
   Embodiments of the present include systems and methods for obtaining the location of a caller during a telephone call. 
   In one embodiment, a phone system obtains the subscriber access line identity of a subscriber access line and sends it to a subscriber location query system which then returns a subscriber location or a subscriber location record. 
   In another embodiment, subscriber phone equipment or phone can store a subscriber access line identity. The subscriber line identity stored in the subscriber phone equipment or phone can be used to retrieve the subscriber location record with the corresponding subscriber access line identity stored its subscriber access line identity attribute and a known location stored in its subscriber location attribute to compare to subscriber access line identities obtained during calls to determine if the subscriber phone equipment has changed location. 
   In yet another embodiment, the emergency call capabilities of a subscriber access line are determined by an emergency call test module sending out a test signal or query to a subscriber access line module, a phone system or subscriber access line. 
   Additional embodiments will be evident from the following detailed description and accompanying drawings, which provide a better understanding of the nature and advantages of the present invention 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  is a block diagram illustrating the connections between subscriber access line module and subscriber phone equipment through a subscriber access line. 
       FIG. 2  is a block diagram illustrating a subscriber location record. 
       FIG. 3  is a block diagram illustrating the connections between a subscriber location datastore and a subscriber location query system. 
       FIG. 4  is a block diagram illustrating a system for obtaining a subscriber location during a call. 
       FIG. 5  is a block diagram illustrating a system for handling an emergency call. 
       FIG. 6  is a block diagram illustrating a method of testing whether or not an emergency call can be made using a subscriber access line. 
       FIG. 7  is a block diagram illustrating a system for determining whether or not subscriber phone equipment has changed location. 
   

   DETAILED DESCRIPTION 
   Subscriber Phone Equipment, Subscriber Access Line, and Subscriber Access Line Module 
     FIG. 1  illustrates a subscriber access line module  130  connection to subscriber phone equipment  110 . Subscriber phone equipment  110  connects to subscriber access line module  130  via a subscriber access line  135 . Subscriber access line module  130  can connect to multiple subscriber phone equipment simultaneously through multiple subscriber access lines. Each subscriber access line  135  has a subscriber access line identity. Each subscriber access line  135  has a subscriber location. The subscriber location of a subscriber access line  135  is the location where the subscriber access line  135  connects to subscriber phone equipment  110 . In one embodiment, a subscriber location includes a street address. In another embodiment, a subscriber location includes a building number. In yet another embodiment, a subscriber location includes a room number. In one embodiment, a subscriber location includes a cubicle number. In a different embodiment, a subscriber location includes a geophysical location. 
   Subscriber access line module  130  manages the association between a subscriber access line  135  and the subscriber access line identity that identifies the subscriber access line  135 . In one embodiment, subscriber access line module  130  includes a Master Distribution Frame (MDF). In another embodiment, subscriber access line module  130  includes a Digital Access Line Access Module (DSLAM). In yet another embodiment, subscriber access line module  130  includes a Digital Loop Carrier (DLC). In a different embodiment, subscriber access line module  130  includes Cable Headend equipment, such as a Cable Modem Termination System (CMTS) or a Cable Data Modem Termination System (CDMTS). In another embodiment, subscriber access line module  130  includes radio network access equipment, such as base stations and base station controllers (BSC). 
   In one embodiment, subscriber access line  135  includes a copper local loop. In another embodiment, subscriber access line  135  includes a coaxial cable. In another embodiment, subscriber access line  135  includes a radio frequency band. In one embodiment, subscriber access line  135  includes a multiplex channel within the radio frequency band. In another embodiment, the multiplex channel is based on Time Division Multiplexing Access (TDMA) technology. In another embodiment, the multiplex channel is based on Code Division Multiplexing Access (CDMA) technology. In yet another embodiment, the multiplex channel is based on Frequency Division Multiplexing Access (FDMA) technology. 
   Subscriber Location Record and Subscriber Location Datastore 
     FIG. 2  illustrates a subscriber location record. A subscriber location record  280  comprises a subscriber access line identity attribute  285  and a subscriber location attribute  287 . In one embodiment, subscriber access line identity attribute  285  includes the subscriber access line identity of a subscriber access line. In one embodiment, subscriber location attribute  287  includes the subscriber location of the subscriber access line. The location stored in the subscriber location attribute can be a physical address such as a street address, a building number, a cubicle number, or geophysical location coordinates. 
   Subscriber Location Datastore and Subscriber Location Query System 
     FIG. 3  illustrates a process for querying a subscriber location. Subscriber location datastore  370  connects to a subscriber location query system  380 . Subscriber location datastore  370  includes a plurality of subscriber location records. Subscriber location query system  380  receives a query for a subscriber location. The query includes a subscriber access line identity  312 . In one embodiment, subscriber location query system  380  compares the subscriber access line identity with the subscriber access line identity attribute of multiple subscriber location records in subscriber location datastore  370 . If a matching subscriber location record exists, subscriber location query system  380  selects one or more of the matching subscriber location record  316 . 
   Subscriber location query system  380  sends the result  318  in response to the query. In one embodiment, the result  318  is the subscriber location extracted from the subscriber location attribute of the selected subscriber location record  316 . In another embodiment, the result is one or more of the selected subscriber location record  316 . 
   In one embodiment, subscriber location query system  380  receives the query from a network. In one embodiment, the network is a Signaling System 7 (SS7) network. In another embodiment, the network is an Internet Protocol (IP) network. In yet another embodiment, subscriber location query system  380  receives the query over a circuitry connection. In a different embodiment, subscriber location query system  380  receives the query over an Application Programming Interface (API). In a one embodiment, subscriber location query system  380  receives the query via a standard base database access protocol. In another embodiment, subscriber location query system  380  receives the query via a proprietary protocol. 
   A Method of Obtaining Subscriber Location During a Call 
     FIG. 4  illustrates a system for obtaining a subscriber location during a call. 
   Subscriber phone equipment  410  connects to a subscriber access line module  430  over a subscriber access line  435 . A phone  417  connects to subscriber access line module  430  over the subscriber access line  435 . Subscriber access line module  430  connects to a phone system  490 . A user uses phone  417  to make a call. 
   Phone system  490  receives and processes the call from phone  417 . Phone system  490  determines the subscriber access line identity of the subscriber access line as to where phone  417  is connected. 
   In one embodiment, phone system  490  determines the subscriber access line identity by correlating the resources in phone system  490 . In one embodiment, the resources include a line card and a port. In another embodiment, the resources include a multiplexing channel in the communications media between phone system  490  and subscriber access line module  430 . 
   In another embodiment, phone system  490  determines the subscriber access line identity by querying subscriber access line module  430 . In one embodiment, phone system  490  queries subscriber access line module  430  during processing of the call. In another embodiment, phone system  490  queries subscriber access line module  430  before the call. 
   In another embodiment, phone system  490  connects to subscriber phone equipment  410 . Subscriber phone equipment  410  obtains the subscriber access line identity of subscriber access line  435  from subscriber access line module  430 . Phone system  490  determines the subscriber access line identity by querying subscriber phone equipment  410 . In one embodiment, phone system  490  queries subscriber phone equipment  410  during processing of the call. In another embodiment, phone system  490  queries subscriber phone equipment  410  before the call. 
   In yet another embodiment, phone  417  stores, includes or otherwise has the subscriber access line identity of subscriber access line  435 . Phone system  490  determines the subscriber access line identity from phone  417 . In one embodiment, phone system  490  determines the subscriber access line identity from phone  417  during processing of the call. In another embodiment, phone system  490  determines the subscriber access line identity from phone  417  before the call. 
   In  FIG. 4 , phone system  490  connects to a subscriber location query system  480 . Phone system  490  sends a query to subscriber location query system  480 . The query includes the determined subscriber access line identity. Phone system  490  receives a subscriber location from subscriber location query system  480 . 
   In one embodiment, phone system  490  connects to another phone system  495 . Phone system  490  sends a call request to phone system  495 . In one embodiment, phone system  490  includes the determined subscriber access line identity in the call request. phone system  495  receives the determined subscriber access line identity from phone system  490 . Phone system  495  determines the subscriber location from the received subscriber access line identity by querying subscriber location query system  480 . 
   A method of Obtaining the Location of a Caller During an Emergency Call. 
     FIG. 5  illustrates a method of handling an emergency call. Phone system  590  connects to an emergency response phone system  595 . Emergency response phone system  595  comprises one or more phone systems. Emergency response phone system  595  connects to subscriber location query system  580 . Subscriber phone equipment  510  connects to a subscriber access line module  530  over a subscriber access line  535 . phone  517  connects to subscriber access line module  530  over the subscriber access line  535 . Subscriber access line module  530  connects to phone system  590 . 
   A user makes an emergency call by dialing an emergency number at phone  517 . In one embodiment, the emergency number is “Emergency”. In another embodiment, the emergency number is “999”. In yet another embodiment, the emergency number is “911”. Phone system  590  receives the emergency call, and determines the subscriber access line identity of subscriber access line  535  as illustrated in  FIG. 4 . 
   Phone system  590  routes the emergency call to emergency response phone system  595  and sends the determined subscriber access line identity to emergency response phone system  595 . 
   Emergency response phone system  595  receives the emergency call and the subscriber access line identity. Emergency response phone system  595  determines the subscriber location by querying the subscriber location query system  580  using the received subscriber access line identity. Emergency response phone system  595  presents the emergency call, including the subscriber location, to an agent. The agent dispatches emergency personnel to subscriber location. In one embodiment, the agent dispatches emergency personnel to the street address indicated in the subscriber location. In an embodiment, the agent dispatches emergency personnel to the cubical of a building indicated in the subscriber location. In a different embodiment, the agent dispatches emergency personnel to search in the geophysical location indicated in the subscriber location. 
   A Method of Obtaining if an Emergency Call can be Made Using a Subscriber Access Line 
     FIG. 6  illustrates a method of obtaining if an emergency call can be made using a subscriber access line. Subscriber phone equipment  610  includes an emergency call test module  615 . Subscriber phone equipment  610  connects to subscriber access line module  630  over subscriber access line  635 . Subscriber access line module  630  connects to a phone system  690 . Emergency call test module  615  performs a test to determine if an emergency call can be made using the subscriber access line  635 . 
   In one embodiment, emergency call test module  615  queries subscriber access line module  630 . Subscriber access line module  630  responds with an indication whether or not an emergency call can be made. Emergency call test module  615  checks the indication. If the indication is positive, emergency call test module  615  determines that an emergency call can be made using the subscriber access line  635 . 
   In another embodiment, subscriber phone equipment  630  connects to phone system  690 . Emergency call test module  615  queries phone system  690 . Phone system  690  responds with an indication whether or not an emergency call can be made. Emergency call test module  615  checks the indication. If the indication is positive, emergency call test module  615  determines that an emergency call can be made using the subscriber access line  635 . 
   In one embodiment, emergency call test module  615  sends an off hook signal towards subscriber access line  635 , and checks for an indication of a dial tone. If the indication is positive, emergency call test module  615  determines that an emergency call can be made using the subscriber access line  635 . 
   In one embodiment, emergency call test module  615  repeats the process a multiple times before determining if an emergency call can be made using the subscriber access line  635 . 
   In one embodiment, subscriber phone equipment  610  connects to a telephone. Subscriber phone equipment  610  informs the telephone if an emergency call can be made using the subscriber access line  635 . 
   In one embodiment, subscriber phone equipment  610  further includes an emergency call test indicator  613 . Emergency call test module  615  connects to an emergency call test indicator  613 . In one embodiment, emergency call test indicator  613  includes a visual indicator such as a light or display. 
   In one embodiment, emergency call test indicator  613  includes a LED as the visual indicator. If emergency call test module  615  determines that an emergency call can be made using the subscriber access line  635 , emergency call test module  615  turns the LED or other visual indicator to green. In one embodiment, if emergency call test module  615  cannot determine an emergency call can be made using the subscriber access line  635 , emergency call test module  615  turns the LED to red. 
   In another embodiment, emergency call test indicator  613  includes a text display panel. If emergency call test module  615  determines an emergency call can be made using the subscriber access line  635 , emergency call test module  615  displays “emergency call Test Succeeds” on the display panel. In one embodiment, emergency call test module  615  cannot determine that an emergency call can be made using the subscriber access line  635  emergency call test module  615  displays “emergency call Test fails” on the display panel. 
   In one embodiment, emergency call test module  615  determines repeatedly if an emergency call can be made using the subscriber access line  635 . In one embodiment, emergency call test module  615  performs the process every 30 minutes. In another embodiment, emergency call test module  615  performs the process every hour. In yet another embodiment, emergency call test module  615  performs the process when subscriber phone equipment  610  powers up. In a different embodiment, emergency call test module  615  performs the process when a telephone call is made. 
   A Method of Determining Whether or not Subscriber Phone Equipment has Changed Location 
     FIG. 7  illustrates a process to determine whether or not subscriber phone equipment has changed location. Subscriber phone equipment  710  includes a location test module  715 . 
   A Method of Determining Whether or not Subscriber Phone Equipment has Changed Location Based on Subscriber Access Line Identity 
   In one embodiment, location test module  715  determines whether or not subscriber phone equipment  710  has changed location by examining the subscriber access line identity of subscriber access line  735 . Subscriber phone equipment  710  connects to subscriber access line module  730  over subscriber access line  735 . Subscriber access line module  730  connects to a phone system  790 . 
   In one embodiment, location test module  715  connects to datastore  719 . Datastore  719  stores a stored subscriber access line identity  718 . The stored subscriber access line identity  718  is a subscriber access line identity identifying a subscriber access line with subscriber location being the correct location of the subscriber phone equipment  710 . In one embodiment, datastore  719  is a flash memory. In another embodiment, datastore is a hard disk. In yet another embodiment, datastore  719  is a memory. 
   Location test module  715  obtains the stored subscriber access line identity  718  and stores the stored subscriber access line identity  718  in datastore  719 . In one embodiment, the stored subscriber access line identity  718  is determined when the service provider establishes a service for the subscriber. In one embodiment, during service establishment, the service provider informs the location test module  715  of the stored subscriber access line identity  718 . In another embodiment, location test module  715  obtains from subscriber access line module  730  the stored subscriber access line identity  718 . In another embodiment, stored subscriber access line identity  718  is determined during a service change. In another scenario, the subscriber moves subscriber phone equipment  710  to a new location, and submits a new address to the service provider. The service provider determines a new stored subscriber access line identity  718 . In another embodiment, the service provider informs the location test module  715  of the new stored subscriber access line identity  718 . In yet another embodiment, location test module  715  obtains from subscriber access line module  730  the new stored subscriber access line identity  718 . 
   In one embodiment, location test module  715  connects to a phone system  790 . Location test module  715  obtains the stored subscriber line identity  718  from phone system  790 . 
   In one embodiment, location test module  715  connects to a phone  717 . Location test module  715  obtains stored subscriber access line identity  718  from phone  717 . 
   In one embodiment, location test module  715  is informed when a new stored subscriber line identity  718  is available. In another embodiment, location test module  715  checks for a new stored subscriber line identity  718 . In an embodiment, location test module  715  checks every 5 minutes. In a different embodiment, location test module  715  checks every hour. 
   Location test module  715  determines whether or not subscriber phone equipment  710  has changed location by matching the stored subscriber access line identity  718  against the subscriber access line identity of subscriber access line  735 . If the match succeeds, location test module  715  concludes that subscriber phone equipment  710  has not changed location. 
   In one embodiment, location test module  715  obtains the subscriber access line identity of subscriber access line  735  from subscriber access line module  730 . In another embodiment, location test module  715  obtains the subscriber access line identity of subscriber access line  735  from phone system  790 . In yet a different embodiment, location test module  715  obtains the subscriber access line identity of subscriber access line  735  from phone  717 . 
   A Method of Determining Whether or not Subscriber Phone Equipment has Changed Location in Voice Over IP (VoIP) Phone Services 
   In one embodiment, phone  717  connects to phone system  790  based on VoIP service. Phone  717  has an IP address. Phone  717  has an IP address as seen by phone system  790 . 
   In one embodiment, location test module  715  sends a message to phone  717 . In one embodiment, phone  717  responds with an indication about whether or not the IP address of phone  717  has changed. In another embodiment, phone  717  responds with an indication about whether or not the IP address of phone  717  as seen by phone system  790  has changed. Location test module  715  can determine based on the indication received from phone  717  whether or not subscriber phone equipment  710  has changed location. 
   In one embodiment, location test module  715  sends a message to phone system  790 . In one embodiment, phone system  790  responds with an indication about whether or not the IP address of phone  717  has changed. In another embodiment, phone system  790  responds with an indication about whether or not the IP address of phone  717  as seen by phone system  790  has changed. Location test module  715  can determine based on the indication received from phone  717  whether or not subscriber phone equipment  710  has changed location. 
   In one embodiment, location test module  715  sends a message to phone  717  and a message to phone system  790 . Location test module  715  concludes that subscriber phone equipment  710  has not changed location if phone  717  responds that the IP address of phone  717  has not changed and phone system  790  responds that the IP address of phone  717  as seen by phone system  790  has not changed. 
   In another embodiment, location test module  715  tests whether or not subscriber phone equipment  710  has changed location every 30 minutes. In another embodiment, location test module  715  tests whether or not subscriber phone equipment  710  has changed location every hour. In yet another embodiment, location test module  715  tests whether or not subscriber phone equipment  710  has changed location when subscriber phone equipment  710  powers up. In a different embodiment, location test module  715  tests whether or not subscriber phone equipment  710  has changed location when a user makes a telephone call. 
   In one embodiment, subscriber phone equipment  710  connects to phone  717 . Subscriber phone equipment  710  informs phone  717  whether or not subscriber phone equipment  710  has changed location. In one embodiment, subscriber phone equipment  710  further includes a location test indicator  713 . Location test module  715  connects to the location test indicator  713 . 
   In according to one embodiment, location test indicator  713  includes a visual indicator such as a light or a display. In one embodiment, the visual indicator is an LED. If location test module  715  determines that subscriber phone equipment  710  has not changed location, location test module  715  turns the LED to green. In one embodiment, if location test module  715  cannot determine that subscriber phone equipment  710  has not changed location, location test module  715  turns the LED to red. In another embodiment, the visual indicator is a display panel. If location test module  715  determines that subscriber phone equipment  710  has not changed location, location test module  717  displays “Location correct” on the display panel. If location test module  715  cannot determine that subscriber phone equipment  710  has not changed location, location Test module  717  displays “Location may be incorrect” on the display panel. 
   Combining Emergency Call Test and Location Test 
   In one embodiment, subscriber phone equipment includes an emergency call test module and a location test module. Subscriber phone equipment can perform both tests provided for by the emergency call test module and the location test module. In one embodiment, subscriber phone equipment further connects to a test indicator. The test indicator can include a visual indicator such as a light or a display. 
   In one embodiment, emergency call test module determines whether or not an emergency call can be made and location test module determines whether or not subscriber phone equipment has changed location. In one embodiment, emergency call test module determines that an emergency call can be made and determines that subscriber phone equipment has not changed locations; then subscriber phone equipment turns the visual indicator, such as an LED, to green. In another embodiment, emergency call test module determines that an emergency call can be made and location test module cannot determine whether or not subscriber phone equipment has changed location; then subscriber phone equipment turns the visual indicator, such as an LED, to yellow. In yet another embodiment, emergency call test module cannot determine that an emergency call can be made and location test module determines that subscriber phone equipment has not changed location; subscriber phone equipment turns the LED to amber. In one other embodiment, emergency call test module cannot determine that an emergency call can be made and location test module cannot determine that subscriber phone equipment has not changed location; subscriber phone equipment turns the LED to red. 
   In a different embodiment, the test indicator visual indicator is a display panel. Subscriber phone equipment displays corresponding messages on the display panel based on the combined test results of emergency call test module and location test module. 
   Subscriber Location Changes During an Emergency Call 
   While a user is making an emergency call, the user may move from a location to another location. The phone system handling the call can discover, from time to time, the subscriber access line identity of the subscriber access line to which the phone is connected. In one embodiment, after obtaining a subscriber access line identity, the phone system sends the subscriber access line identity to the emergency response phone system. In another embodiment, the phone system detects a change in subscriber access line identity, and sends the new subscriber access line identity to the emergency response phone system. The emergency response phone system further presents to the agent with an updated subscriber location. 
   A Method of Selecting a Phone System While Making Emergency Calls in a VoIP Service Scenario 
   In  FIG. 5 , when a phone  517  makes an emergency call, phone  517  routes the emergency call to a phone system  590 . In one embodiment, the telephone service is a VoIP service. The VoIP service provider is typically not the service provider for the subscriber access line  535 . In one embodiment, the subscriber access line service provider offers telephone services and has a plurality of phone system from the subscriber access line service provider. When a user makes an emergency call, the user can select a phone system from the subscriber access line service provider to handle the emergency call. 
   In one embodiment, the phone  517  recognizes the emergency call and routes the emergency call to a phone system from the subscriber access line service provider. In another embodiment, the phone  517  is connected to the subscriber phone equipment  510 . The subscriber phone equipment  510  recognizes the emergency call and routes the emergency call to a phone system from the subscriber access line service provider. 
   In another embodiment, the subscriber access line module  530  recognizes the emergency call and routes the emergency call to a phone system from the subscriber access line service provider. 
   Types of Phone Calls that Require Subscriber Location Information 
   The above description applies to emergency calls that require subscriber location information. However, there are many other scenarios in which would be helpful, advantageous or necessary to obtain the subscriber location of a telephone call. In one embodiment, phone system can use subscriber access line identities to determine the location information for calls such as location specific directory services, marketing information for premium pay per use phone services and toll-free service calls. 
   Described herein are techniques for methods and systems of obtaining the location of a caller during an emergency phone call. In the following description, for purposes of explanation, numerous examples and specific details are set forth in order to provide a thorough understanding of the present invention. It will be evident, however, to one skilled in the art that the present invention as defined by the claims may include some or all of the features in these examples alone or in combination with other features described below, and may further include obvious modifications and equivalents of the features and concepts described herein.