# UserDefinedMessages subresource > \[!NOTE] > > See the [Voice SDK Call Message Events page](/docs/voice/sdks/call-message-events) for more information. UserDefinedMessages is a subresource of [Calls](/docs/voice/api/call-resource) and represents a user-defined message that is sent to a Voice SDK end user during an active call. A UserDefinedMessage subresource can only be created during an active call associated with the Voice SDK. Read more about the Voice SDK messaging feature on the [Voice SDK Call Message Events Page](/docs/voice/sdks/call-message-events). ## UserDefinedMessages properties ```json {"type":"object","refName":"api.v2010.account.call.user_defined_message","modelName":"api_v2010_account_call_user_defined_message","properties":{"account_sid":{"type":"string","minLength":34,"maxLength":34,"pattern":"^AC[0-9a-fA-F]{32}$","nullable":true,"description":"The SID of the [Account](/docs/iam/api/account) that created User Defined Message."},"call_sid":{"type":"string","minLength":34,"maxLength":34,"pattern":"^CA[0-9a-fA-F]{32}$","nullable":true,"description":"The SID of the [Call](/docs/voice/api/call-resource) the User Defined Message is associated with."},"sid":{"type":"string","minLength":34,"maxLength":34,"pattern":"^KX[0-9a-fA-F]{32}$","nullable":true,"description":"The SID that uniquely identifies this User Defined Message."},"date_created":{"type":"string","format":"date-time-rfc-2822","nullable":true,"description":"The date that this User Defined Message was created, given in RFC 2822 format."}}} ``` ## Create a UserDefinedMessage `POST https://api.twilio.com/2010-04-01/Accounts/{AccountSid}/Calls/{CallSid}/UserDefinedMessages.json` ### Path parameters ```json [{"name":"AccountSid","in":"path","description":"The SID of the [Account](/docs/iam/api/account) that created User Defined Message.","schema":{"type":"string","minLength":34,"maxLength":34,"pattern":"^AC[0-9a-fA-F]{32}$"},"required":true},{"name":"CallSid","in":"path","description":"The SID of the [Call](/docs/voice/api/call-resource) the User Defined Message is associated with.","schema":{"type":"string","minLength":34,"maxLength":34,"pattern":"^CA[0-9a-fA-F]{32}$"},"required":true}] ``` ### Request body parameters ```json {"schema":{"type":"object","title":"CreateUserDefinedMessageRequest","required":["Content"],"properties":{"Content":{"type":"string","description":"The User Defined Message in the form of URL-encoded JSON string."},"IdempotencyKey":{"type":"string","description":"A unique string value to identify API call. This should be a unique string value per API call and can be a randomly generated."}}},"examples":{"create":{"value":{"lang":"json","value":"{\n \"Content\": \"{\\\"key\\\":\\\"value\\\"}\",\n \"IdempotencyKey\": \"1\"\n}","meta":"","code":"{\n \"Content\": \"{\\\"key\\\":\\\"value\\\"}\",\n \"IdempotencyKey\": \"1\"\n}","tokens":[["{","#C9D1D9"],"\n ",["\"Content\"","#7EE787"],[":","#C9D1D9"]," ",["\"{","#A5D6FF"],["\\\"","#79C0FF"],["key","#A5D6FF"],["\\\"","#79C0FF"],[":","#A5D6FF"],["\\\"","#79C0FF"],["value","#A5D6FF"],["\\\"","#79C0FF"],["}\"","#A5D6FF"],[",","#C9D1D9"],"\n ",["\"IdempotencyKey\"","#7EE787"],[":","#C9D1D9"]," ",["\"1\"","#A5D6FF"],"\n",["}","#C9D1D9"]],"annotations":[],"themeName":"github-dark","style":{"color":"#c9d1d9","background":"#0d1117"}}}},"encodingType":"application/x-www-form-urlencoded","conditionalParameterMap":{}} ``` Send a message from the server side to the Voice SDK by making a `POST` request to an active Call's UserDefinedMessages endpoint. The content of your message is contained in the `Content` parameter of your request as a stringified JSON object. Use the appropriate Call SID in the path of your `POST` request. Use the parent Call SID if you wish to send a message to parent Call leg. Use the child Call SID if you wish to send a message to the child Call leg. See the [Voice SDK Overview page](/docs/voice/sdks#call-legs-with-voice-sdk-calls) for more information on Voice SDK Call legs. Send a UserDefinedMessage to an SDK end-user ```js // Download the helper library from https://www.twilio.com/docs/node/install const twilio = require("twilio"); // Or, for ESM: import twilio from "twilio"; // Find your Account SID and Auth Token at twilio.com/console // and set the environment variables. See http://twil.io/secure const accountSid = process.env.TWILIO_ACCOUNT_SID; const authToken = process.env.TWILIO_AUTH_TOKEN; const client = twilio(accountSid, authToken); async function createUserDefinedMessage() { const userDefinedMessage = await client .calls("CAaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa") .userDefinedMessages.create({ content: JSON.stringify({ example_key: "Hello from the server side!" }), }); console.log(userDefinedMessage.accountSid); } createUserDefinedMessage(); ``` ```python # Download the helper library from https://www.twilio.com/docs/python/install import os from twilio.rest import Client import json # Find your Account SID and Auth Token at twilio.com/console # and set the environment variables. See http://twil.io/secure account_sid = os.environ["TWILIO_ACCOUNT_SID"] auth_token = os.environ["TWILIO_AUTH_TOKEN"] client = Client(account_sid, auth_token) user_defined_message = client.calls( "CAaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" ).user_defined_messages.create( content=json.dumps({"example_key": "Hello from the server side!"}) ) print(user_defined_message.account_sid) ``` ```csharp // Install the C# / .NET helper library from twilio.com/docs/csharp/install using System; using Twilio; using Twilio.Rest.Api.V2010.Account.Call; using System.Threading.Tasks; using System.Collections.Generic; using Newtonsoft.Json; class Program { public static async Task Main(string[] args) { // Find your Account SID and Auth Token at twilio.com/console // and set the environment variables. See http://twil.io/secure string accountSid = Environment.GetEnvironmentVariable("TWILIO_ACCOUNT_SID"); string authToken = Environment.GetEnvironmentVariable("TWILIO_AUTH_TOKEN"); TwilioClient.Init(accountSid, authToken); var userDefinedMessage = await UserDefinedMessageResource.CreateAsync( content: JsonConvert.SerializeObject( new Dictionary() { { "example_key", "Hello from the server side!" } }, Formatting.Indented), pathCallSid: "CAaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"); Console.WriteLine(userDefinedMessage.AccountSid); } } ``` ```java // Install the Java helper library from twilio.com/docs/java/install import java.util.HashMap; import com.twilio.Twilio; import com.twilio.rest.api.v2010.account.call.UserDefinedMessage; import org.json.JSONObject; public class Example { // Find your Account SID and Auth Token at twilio.com/console // and set the environment variables. See http://twil.io/secure public static final String ACCOUNT_SID = System.getenv("TWILIO_ACCOUNT_SID"); public static final String AUTH_TOKEN = System.getenv("TWILIO_AUTH_TOKEN"); public static void main(String[] args) { Twilio.init(ACCOUNT_SID, AUTH_TOKEN); UserDefinedMessage userDefinedMessage = UserDefinedMessage .creator("CAaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", new JSONObject(new HashMap() { { put("example_key", "Hello from the server side!"); } }).toString()) .create(); System.out.println(userDefinedMessage.getAccountSid()); } } ``` ```go // Download the helper library from https://www.twilio.com/docs/go/install package main import ( "encoding/json" "fmt" "github.com/twilio/twilio-go" api "github.com/twilio/twilio-go/rest/api/v2010" "os" ) func main() { // Find your Account SID and Auth Token at twilio.com/console // and set the environment variables. See http://twil.io/secure // Make sure TWILIO_ACCOUNT_SID and TWILIO_AUTH_TOKEN exists in your environment client := twilio.NewRestClient() Content, ContentError := json.Marshal(map[string]interface{}{ "example_key": "Hello from the server side!", }) if ContentError != nil { fmt.Println(ContentError) os.Exit(1) } params := &api.CreateUserDefinedMessageParams{} params.SetContent(string(Content)) resp, err := client.Api.CreateUserDefinedMessage("CAaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", params) if err != nil { fmt.Println(err.Error()) os.Exit(1) } else { if resp.AccountSid != nil { fmt.Println(*resp.AccountSid) } else { fmt.Println(resp.AccountSid) } } } ``` ```php calls("CAaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa") ->userDefinedMessages->create( json_encode([ "example_key" => "Hello from the server side!", ]) // Content ); print $user_defined_message->accountSid; ``` ```ruby # Download the helper library from https://www.twilio.com/docs/ruby/install require 'twilio-ruby' # Find your Account SID and Auth Token at twilio.com/console # and set the environment variables. See http://twil.io/secure account_sid = ENV['TWILIO_ACCOUNT_SID'] auth_token = ENV['TWILIO_AUTH_TOKEN'] @client = Twilio::REST::Client.new(account_sid, auth_token) user_defined_message = @client .api .v2010 .calls('CAaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa') .user_defined_messages .create( content: { 'example_key' => 'Hello from the server side!' }.to_json ) puts user_defined_message.account_sid ``` ```bash EXCLAMATION_MARK='!' # Install the twilio-cli from https://twil.io/cli twilio api:core:calls:user-defined-messages:create \ --call-sid CAaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa \ --content "{\"example_key\":\"Hello from the server side$EXCLAMATION_MARK\"}" ``` ```bash EXCLAMATION_MARK='!' CONTENT_OBJ=$(cat << EOF { "example_key": "Hello from the server side$EXCLAMATION_MARK" } EOF ) curl -X POST "https://api.twilio.com/2010-04-01/Accounts/$TWILIO_ACCOUNT_SID/Calls/CAaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa/UserDefinedMessages.json" \ --data-urlencode "Content=$CONTENT_OBJ" \ -u $TWILIO_ACCOUNT_SID:$TWILIO_AUTH_TOKEN ``` ```json { "account_sid": "ACaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", "call_sid": "CAaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", "sid": "KXaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", "date_created": "Wed, 18 Dec 2019 20:02:01 +0000" } ``` ## Related resources Go to the [Voice SDK Call Message Events page](/docs/voice/sdks/call-message-events) to learn more.