---
title: "Create a new User Defined Message for the given Call SID."
method: POST
path: "/2010-04-01/Accounts/{AccountSid}/Calls/{CallSid}/UserDefinedMessages.json"
tags: ["Api20100401UserDefinedMessage"]
---

# Create a new User Defined Message for the given Call SID.

`POST /2010-04-01/Accounts/{AccountSid}/Calls/{CallSid}/UserDefinedMessages.json`

## Request

- Base URL: `https://api.twilio.com`
- URL: `https://api.twilio.com/2010-04-01/Accounts/{AccountSid}/Calls/{CallSid}/UserDefinedMessages.json`
- Auth: HTTP basic

Create a new User Defined Message for the given Call SID.

## Path parameters

- `AccountSid` string, required
- `CallSid` string, required

## Request body `application/x-www-form-urlencoded`

- object
  - `Content` string, required: The User Defined Message in the form of URL-encoded JSON string.
  - `IdempotencyKey` string: A unique string value to identify API call. This should be a unique string value per API call and can be a randomly generated.

## Response `201`

Created

- ApiV2010AccountCallUserDefinedMessage
  - `account_sid` string, nullable: The SID of the [Account](https://www.twilio.com/docs/iam/api/account) that created User Defined Message.
  - `call_sid` string, nullable: The SID of the [Call](https://www.twilio.com/docs/voice/api/call-resource) the User Defined Message is associated with.
  - `sid` string, nullable: The SID that uniquely identifies this User Defined Message.
  - `date_created` string, date-time-rfc-2822, nullable: The date that this User Defined Message was created, given in RFC 2822 format.

---

[API](https://skmtc.dev/twilio/apis/api-v2010.md) - [All operations](https://skmtc.dev/twilio/apis/api-v2010/llms.txt) - [OpenAPI document](https://skmtc.dev/twilio/apis/api-v2010/revisions/bfdf249a1298?raw)