How Entry and Exit Detection Works

Position Health provides medical facility entry and exit tracking to our customers through the use of our mobile software development kit (SDK).  Customers embed our SDK within their user-facing mobile apps, after which our SDK provides geolocation-based event detection and notification.  Position Health Inside is how we describe this integration and customer app augmentation approach.

In the sections that follow, we:

  • Provide background on our technology.

  • Describe our approach to maintaining the privacy of our customers’ users.

  • Walk through the most common customer workflow leveraging our SDK to track medical facility entries and exits.

Background on Technology

Position Health uses geofencing technology to detect when users enter or exit medical facilities.  A geofence is a virtual geographic boundary that triggers actions when a user with a smartphone enters and exits it.  Position Health uses geofencing technology to:

  • Manage, fluidly update, and customize geofences relevant to each user and customer (emergency departments, skilled nursing facilities, imaging centers, dialysis centers, etc.).

  • Minimize battery drain and data use.

  • Send alerts when users enter or exit a Position Health geofence.

Position Health’s functionality is implemented for customers via our mobile software development kit (SDK) or a white label app.

User Privacy

The privacy of your users is very important to us.  The only information that the app collects is:

  • When a user enters or exits a medical facility in the United States.

  • Which medical facility they entered or exited.

  • The medical facilities' contact information.

Position Health detects user medical facility entries and exists using geofencing.  One benefit of using geofencing is that it increases privacy for users.  Due to our use of geofencing, Position Health does not track the location of our users.  In fact, we only know where our users are when they enter one of our geofences.


The following page describes creating and monitoring geofences:


The following page describes creating and monitoring geofences:

User Enrollment Summary

User enrollment is the process whereby your users are registered within the Position Health system.  With a small investment of your development resources we can work with you to build an API based integration with Position Health.  This will enable an enrollment process that:

  • Is completely transparent to your users.

  • Is in-line with the current paradigms within your existing application.

  • Maintains 100% user anonymity within the Position Health system. 

User Enrollment in Depth

Loading Nearby Fences

Initial Load

After the user enrollment process completes, the Position Health SDK loads 20 geofences nearest the users’ current location. 


The SDK maintains these geofences and, when user travels, automatically updates its geofences.

Our Network

Our network of geofences includes 5,000 hospitals in the United States with our enrichment process being completed for every emergency department in New England.  Other facilities can be added to the network within days.

Scalable and Customizable

The geofencing technology leveraged by Position Health allows us to scale beyond the United States.  Our fences consist of a lat/lng center point and radius – which means that the capabilities our product provides can work for your users wherever they are.


Detecting When A Fence Event Occurs

Position Health detects any time users enter and exit medical facilities.  Fence entry and exit events are detected by the Position Health SDK and the event data is stored in our database. 

Entry and Exit Linking

Fence exit events are linked to the related fence entry event. 

Fence Event Detection Sensitivity

Fence entry and exit event detection is highly sensitive, which helps minimize false negatives – cases where users do enter a geofence and it is not detected.

Position Health Portal View of Fence Events

Initiating A Dwell Check

Whenever a fence event is sent to Position Health, our servers decide if a dwell check determination is required.  A dwell check determination is the process of deciding if a user is actually dwelling within the geofence or just passing by.  After completion of the dwell check determination process a dwell check event is stored in our database.

Dwell Check to Fence Event Linking

Dwell check events are linked to the related fence entry event.

Reduction of False Positives

The dwell check determination process is essential because it converts the highly sensitive fence event data into an accurate record of user medical facility entry activity.  Position Health has invested heavily in the development and tuning of our dwell check determination algorithm so as to reduce false positives – cases where users pass nearby or through a medical facility but, in fact, are not there seeking care.

Position Health Portal View of Dwell Checks

Requesting Confirmation from User on Mobile Device

When the Position Health dwell determination decides that a user is dwelling within a medical facility, the Position Health SDK raises a local notification on the users’ mobile phone.  We call this local notification an Alert Prompt.  It gives the user the ability to confirm their medical facility visitation.  Confirmed visitations and ignored notifications are stored in our database.

Alert Prompts



Confirming a Visitation (Ping)

Reduction of False Positives

Position Health uses Alert Prompts to further reduce the possibility of false positives by requiring that users confirm medical facility entry detections made by the Position Health SDK. 

Automatic Confirmation

Position Health has automatic confirmation functionality that can confirm user medical facility visitations in cases where users are not able to do so.

Customizing Alert Prompts

Position Health supports various customizations to the Alert Prompt notifications raised by our SDK.

Position Health Portal View of Confirmed Medical Facility Visitations (Pings)

Position Health Portal View of Ignored Notifications

Event Polling Summary

Position Health data exports can be configured for dwell check events and confirmed medical facility visitation events.  The exports are performed by the customer via polling REST services and the data is exported in JSON format. 

Considering that users are tracked anonymously within Position Health, it is necessary for our customers to resolve the Position Health user to the actual user within their system.  Customers have done this by maintaining the Position Health user id on the user records within their data store.

Dwell check events

The JSON data exported for these events includes the following:

  • Position Health user id

  • Hospital name

  • Hospital phone number

  • Kind (fence-entry/ed-visit/admission/discharge)

  • Is dwell (yes/no)

  • Dwell check date

Confirmed medical facility visitation events

The JSON data exported for these events includes the following:

  • Position Health user id

  • Hospital name

  • Hospital phone number

  • Originator (user/auto)

  • Kind (ed-visit/admission/discharge)

  • Confirmed visitation date

Event Polling in Depth


This document describes a common customer workflow made possible by the integration of the Position Health SDK into user-facing mobile applications. 

Our SDK delivery approach as well as our focus on location enables Position Health to help our customers leverage user generated location data to better and more cost-effectively manage care.