Action was taken by the FCC on January 29, 2015, with respect to E911 location technology by the Fourth Report and Order (FCC 15-9).The following revisions to the wireless E911 rules (see [12] and [13] for the specific rules) are reproduced from the Fourth Report and Order (revisions on compliance, enforcement, testing, test bed, reporting, submission of plans and reports is not included):

• Location Delivery Latency (Time to First Fix) is set at a maximum of 30 seconds from the time the user initiates an emergency service call to the time it is available at the location information center.
• Defines the following:
  1. Dispatchable location: A location delivered to the PSAP by the network with an emergency service call that consists of the street address of the calling party, plus additional information such as suite, apartment or similar information necessary to adequately identify the location of the calling party. The street address of the calling party must be validated and, to the extent possible, corroborated against other location information prior to delivery of dispatchable location information by the PLMN operator to the PSAP.
  2. National Emergency Address Database (NEAD): A database that utilizes MAC address information to identify a dispatchable location for nearby wireless devices within the PLMN operator's coverage area.
  3. Nationwide PLMN operator: a PLMN operator whose service extends to a majority of the population and land area of the United States.
  4. Non-nationwide PLMN operator: Any PLMN operator other than a nationwide PLMN operator.
• Sets the following indoor location accuracy standards for 911 calls:
  1. For horizontal location
     1. Nationwide PLMN operators shall provide either a dispatchable location or x/y location within 50 meters for the following percentages of wireless emergency service calls within the following timeframes from the effective date of the adoption of these rules
        1. Within 2 years: 40% of all wireless emergency service calls
        2. Within 3 years: 50% of all wireless emergency service calls
        3. Within 5 years: 70% of all wireless emergency service calls
        4. Within 6 years: 80% of all wireless emergency service calls
     2. Non-nationwide PLMN operators shall provide either a dispatchable location or x/y location within 50 meters for the following percentages of wireless emergency service calls within the following timeframes from the effective date of the adoption of these rules
        1. Within 2 years: 40% of all wireless emergency service calls
        2. Within 3 years: 50% of all wireless emergency service calls
        3. Within 5 years or within 6 months of deploying VoLTE whichever is later: 70% of all wireless service calls
        4. Within 6 years or within one year of deploying VoLTE, whichever is later: 80% of all wireless emergency service calls
  2. For vertical location, PLMN operators shall provide vertical location information with wireless emergency service calls within the following timeframes from the effective date of the adoption of these rules
     1. Within 3 years: All PLMN operators shall make uncompensated barometric data available to PSAPs with respect to any 911 call placed from any UE with the capability to deliver barometric sensor information
     2. Within 3 years: Nationwide PLMN operators shall develop one or more z-axis metrics validated by an independently administered and transparent test bed process and shall submit the proposed metrics and testing results to the FCC for approval.
     3. Within 6 years: In each of the top 25 Cellular Market Areas (CMA), nationwide PLMN operators shall deploy either dispatchable location or z-axis technology in compliance with any z-axis accuracy metric that has been approved by the FCC.
        1. In each CMA where dispatchable location is used: nationwide PLMN operators must ensure that the NEAD is populated with a sufficient number of total dispatchable location reference points to equal 25% of the CMA population.
        2. In each CMA where z-axis is used: nationwide PLMN operators must deploy z-axis technology to cover 80% of the CMA population.
     4. Within 8 years: In each of the top 50 CMAs, nationwide PLMN operators shall deploy either dispatchable location or such z-axis technology in compliance with any z-axis accuracy metric that has been approved by the FCC.
     5. Non-nationwide PLMN operators that serve any of the top 25 or 50 CMAs will have an additional year to meet the vertical location benchmarks in C & D.
• Specifies the delivery of location confidence and uncertainty data
  1. PLMN operators shall provide for all wireless emergency service calls, whether from outdoor or indoor locations, x- and y-axis confidence and uncertainty information on a per-call basis upon the request of a PSAP. The data shall specify the caller's location with a uniform confidence level of 90 percent and the radius in meters from the reported position at the same confidence level. All entities responsible for transporting confidence and uncertainty between CMRS providers and PSAPs including PLMN operators, owners of E911 networks and emergency service providers, must enable the transmission of confidence and uncertainty data provided by PLMN operators to the requesting PSAP.
  2. Upon meeting the 3 year timeframe for the horizontal location standards, PLMN operators shall provide with emergency service calls that have a dispatchable location the confidence and uncertainty data for the x- and y- axis required in these regulations.
  3. Upon meeting the 6 year timeframe for the horizontal location standards, PLMN operators shall provide with wireless emergency service calls that have a dispatchable location the confidence and uncertainty data for the x- and y- axis required in these regulations.
• Specifies the live emergency service call data recording requirements
  1. PLMN operators must record information on all live emergency calls including, but not limited to, the positioning source method used to provide a location fix associated with the call. PLMN operators must also record the confidence and uncertainty data they provide. This information must be made available to PSAPs upon request, and shall be retained for a period of two years.
• Defines when the requirements of the location accuracy regulations apply
  1. The requirements shall be applicable only to the extent that the administrator of the applicable designated PSAP has requested the services required under these regulations and the PSAP is capable of receiving and utilizing the requested data elements and has a mechanism for recovering the PSAP's costs associated with them.