> ## Documentation Index
> Fetch the complete documentation index at: https://developer.eka.care/llms.txt
> Use this file to discover all available pages before exploring further.

# Overview

## User Session

Upon registration or creation of an ABHA, a user session is maintained with the ABHA Gateway.
This session expires after a certain period. When the session expires, APIs requiring ABHA Gateway authentication will return a `491` HTTP response code.

A ABHA Gateway Session creation requires a Mobile OTP (One-Time Password) Authentication.

**1. Generate Mobile OTP**

Use the [Initiate Session: Generate Mobile OTP](https://developer.eka.care/api-sdk/hie-cm/session/init.md) endpoint to start a new session by generating a mobile OTP.
This session is linked to the provided ABHA address, and a `txn_id` (Transaction ID) will be returned for tracking and verification.

**2. Verify Mobile OTP**

Use the [Verify Mobile OTP: Get User Session Token](https://developer.eka.care/api-sdk/hie-cm/session/verify.md) endpoint to verify the OTP generated in the previous step.
Provide the OTP and `txn_id` associated with the session to receive an access token for further authentication.

***

## Check User Session Status

Before initiating OTP authentication, clients **should first check whether a valid ABHA Gateway session already exists**.

Use the **Session Status API** to get the current authentication status of the user.

* If a valid session exists, continue using the existing session token
* If no valid session exists or the session has expired, users should call:
  * **Generate Mobile OTP**
  * **Verify Mobile OTP**


This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.