Overview#
A caller dials 911 from the fourteenth floor of an office building. Their cell phone pings three towers. The address is correct, but "fourteenth floor" is the detail that tells the responding unit which stairwell to use. Traditional E911 gets you the building. The PSAP Location Services module gets you the floor.
The module delivers precision emergency location intelligence for 911 call handling, combining Phase I cell tower identification and Phase II GPS-based positioning with GIS mapping integration, address validation, and nearest-unit dispatch recommendations. Both legacy Enhanced 911 (E911) and Next Generation 911 / 112 (NG911 / NG112) location standards are supported, with hybrid positioning that combines GPS, WiFi, Bluetooth, and cellular signals to achieve indoor and outdoor accuracy that exceeds FCC compliance requirements.
Key Features#
- Phase I & Phase II Location: FCC-mandated E911 location services with Phase I cell tower identification for approximate positioning and Phase II GPS/network-based positioning for precise caller location, including hybrid methods combining GPS, WiFi, Bluetooth, and barometric pressure for indoor floor-level detection
- Location Confidence Scoring: Automated 0-100 confidence scoring based on GPS signal strength, horizontal accuracy, fix age, indoor/outdoor detection, caller velocity, and cross-validation between multiple positioning sources, displayed to dispatchers with clear interpretation guidance
- GIS Mapping Integration: High-resolution real-time mapping with multi-layer visualisation including caller location, unit positions, incident markers, jurisdictional boundaries, emergency resources, hazards, infrastructure, weather overlays, and traffic conditions with support for multiple mapping providers
- Address Validation & Geocoding: Cross-referencing caller-provided addresses against authoritative civic address databases with fuzzy matching for misspellings, intersection parsing, landmark recognition for 25,000+ named locations, and multi-source validation with confidence scoring
- Nearest Unit Dispatch: Automated identification of the closest available emergency resource based on real-time GPS tracking, driving distance with traffic conditions, estimated time of arrival, unit capability matching, and current unit status with automatic, recommended, and manual dispatch modes
- Real-Time Caller Tracking: Continuous position updates every 5 seconds for moving callers with velocity and heading indicators, movement history, and automatic map tracking for vehicle-based emergency calls
- Offline Resilience: Seven-day cached map tiles and local address databases ensure location services continue operating during network outages with automatic synchronisation when connectivity is restored
- FCC Compliance Monitoring: Automated tracking and reporting of Phase II accuracy, availability, vertical location, and response time metrics against FCC requirements with quarterly compliance report generation
Use Cases#
- Emergency Caller Location: Display precise caller location on the dispatch map before the call is answered, with confidence scoring and address validation to ensure accurate initial dispatch and eliminate wrong-address responses
- Indoor Emergency Response: Locate callers inside buildings using WiFi, Bluetooth, and barometric pressure positioning with floor-level detection for high-rise incidents, multi-story hospitals, shopping centres, and airport terminals
- Nearest Unit Selection: Automatically recommend the closest available unit based on real-time GPS tracking, driving distance with traffic, unit capabilities, and incident type to reduce response times compared to manual unit selection
- Rural Emergency Location: Provide usable location information in areas without house numbers or landmarks using GPS coordinates, nearest known landmark display, and cell tower-based approximate positioning for sparse coverage areas
- Multi-Unit Coordination: Route multiple responding units via different paths to prevent convoy bunching, recommend staging locations, and provide mutual aid unit recommendations when local resources are exhausted
Integration#
The module integrates with E911 selective routers and NG911 / NG112 ESInet-style infrastructure for call and location delivery, ALI databases for wireline location identification, wireless carrier positioning systems for Phase I and Phase II location, GIS providers for mapping and geocoding, CAD systems for unit tracking and dispatch, and traffic data services for routing optimisation. Supports operations for island and remote emergency services where GPS-only positioning may be the primary means of location.
Open Standards#
- NENA i3 / NENA-STA-010 (NG9-1-1 / NG1-1-2 Core Services): The capability conforms to the NENA i3 architecture for call routing, Emergency Call Routing Function (ECRF), Location Validation Function (LVF), and Emergency Services Routing Proxy (ESRP) interactions within an ESInet-style infrastructure.
- RFC 5222 (LoST, Location-to-Service Translation Protocol): An async LoST client builds findService and listServicesByLocation requests to resolve caller coordinates or civic addresses to the correct PSAP or emergency-service boundary.
- RFC 4119 + RFC 5491 (PIDF-LO, Presence Information Data Format Location Object): Caller location is encoded as PIDF-LO XML with GML Point geometry in WGS-84 (EPSG:4326) for transmission to LoST servers and NG1-1-2 selective routers.
- RFC 7852 (Additional Data Related to an Emergency Call): The Additional Data Repository surfaces the seven NENA-STA-012 standard block types, attaching caller, subscriber, and service-provider records to each emergency call per this IETF specification.
- NENA-STA-006.3 (NG9-1-1 GIS Data Model): All civic address, road centreline, site/structure address point, and Emergency Service Boundary layers are validated and stored to the NENA-STA-006.3 schema; coordinate reference system compliance (WGS-84) is enforced at ingest.
- EN 17128:2020 (Advanced Mobile Location, AML): Incoming AML SMS bodies from handsets are parsed to the EN 17128 key-value format, extracting WGS-84 latitude/longitude, positioning method, and accuracy radius for automatic pre-answer caller location.
- EN 15722:2015 / ISO 29283 + ETSI TS 103 479 (eCall Minimum Set of Data / NG-eCall): The eCall ingester decodes the 140-byte fixed PER MSD binary per EN 15722:2015 Annex C and the NG-eCall Additional Data Set per ETSI TS 103 479, feeding vehicle crash location into the dispatch map.
- NMEA 0183 / TAIP (AVL unit positioning protocols): Real-time unit tracking accepts both NMEA 0183 sentences and Trimble TAIP messages from vehicle-mounted GPS transponders, normalising all observations to WGS-84 for nearest-unit dispatch calculations.
Last Reviewed: 2026-01-09 Last Updated: 2026-01-09