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

# Authentication

Before making any API calls, authenticate to obtain an access token.

<Steps>
  <Step title="Sign-in via phone number">
    All API endpoints are authenticated using Bearer HTTP authentication.
    Call [POST /request-otp](/api-reference/endpoint/auth/request-otp) to send an SMS message with an OTP code to your phone number
  </Step>

  <Step title="Verify One-Time Password code">
    After receiving the one-time password in SMS message, you need to [verify (POST /verify-otp)](/api-reference/endpoint/auth/verify-otp) code to get an access token.
  </Step>

  <Step title="Save access token">
    Pass the `token` from the response for subsequent API requests in the Authorization property.
  </Step>
</Steps>