# Issue a push notification that can be used to step-up a token

Initiates the step-up token process by submitting a push notification to a device belonging to the logged-in user that was previously enrolled through the /authentication_factors/push/{channel} endpoint.

You should only start this process if the token step-up isn't already in flight.

Endpoint: POST /stepup/challenges/push/{channel}
Version: 3.63.5
Security: auth_token, api-key

## Header parameters:

  - `idempotency-ref` (string)
    A unique call reference generated by the caller that, taking into consideration the payload as well as the operation itself, helps avoid duplicate operations. Idempotency reference uniqueness is maintained for at least 24 hours.

## Path parameters:

  - `channel` (string, required)
    - "AUTHY": The push notification is sent on the user's device using Twilio Authy
- "BIOMETRIC": The push notification is sent to the user's device
    Enum: "AUTHY", "BIOMETRIC"

## Response 200 fields (application/json):

  - `id` (string)
    The challenge id.

## Response 400 fields (application/json):

  - `message` (string)
    When present helps to identify and fix the problem.

  - `syntaxErrors` (object)
    Is returned as part of an HTTP error response whenever a syntax error is detected. A list of the fields together with their syntax error will be provided.

  - `syntaxErrors.invalidFields` (array)

  - `syntaxErrors.invalidFields.params` (array)

  - `syntaxErrors.invalidFields.fieldName` (string)

  - `syntaxErrors.invalidFields.error` (string)
    Enum: "REQUIRED", "HAS_TEXT", "REQUIRES", "SIZE", "RANGE", "IN", "NOT_IN", "REGEX", "EXACTLY", "AT_LEAST", "AT_MOST", "ALL_OR_NONE"

## Response 405 fields (application/json):

  - `code` (string)

  - `message` (string)

## Response 409 fields (application/json):

  - `errorCode` (string)
    Enum: "STATE_INVALID", "CHANNEL_NOT_SUPPORTED", "CHANNEL_NOT_REGISTERED", "CHALLENGE_LIMIT_EXCEEDED"

## Response default fields (application/json):

  - `code` (string)

  - `message` (string)


## Response 401 fields

## Response 403 fields

## Response 429 fields

## Response 500 fields

## Response 503 fields