---
title: "Sign in with SMS OTP"
method: POST
path: "/signin/passwordless/sms"
tags: ["authentication"]
---

# Sign in with SMS OTP

`POST /signin/passwordless/sms`

Initiate passwordless authentication by sending a one-time password to the user's phone number. If the user doesn't exist, a new account will be created with the provided options.

## Request body

- SignInPasswordlessSmsRequest
  - `phoneNumber` string, required — Phone number of the user
  - `options` SignUpOptions
    - `allowedRoles` string[]
    - `defaultRole` string
    - `displayName` string
    - `locale` string — A two-characters locale
    - `metadata` object
    - `redirectTo` string, uri

## Response `200`

OTP sent to user's phone number successfully

- 'OK'

## Other responses

- `default` — An error occurred while processing the request

## Changes

- **2025-10-09** `2bb5c4e40463` — 1 breaking, 1 warning, 3 info
  - the `options/locale` request property's maxLength was decreased to `2`
  - added the new `email-already-in-use` enum value to the `error` response property for the response status `default`
  - removed the `otp-too-many-attempts` enum value from the `error` response property for the response status `default`
  - removed the `provider-account-already-linked` enum value from the `error` response property for the response status `default`
  - …1 more

[Change history](https://skmtc.dev/nhost/apis/nhost-authentication-api/changes/signin/passwordless/sms/post.md)

---

[API](https://skmtc.dev/nhost/apis/nhost-authentication-api.md) · [All operations](https://skmtc.dev/nhost/apis/nhost-authentication-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/nhost/nhost-authentication-api/revisions/2bb5c4e40463/schema)