---
title: "Add a new participant to the conversation in a specific service"
method: POST
path: "/v1/Services/{ChatServiceSid}/Conversations/{ConversationSid}/Participants"
tags: ["ConversationsV1Participant"]
---

# Add a new participant to the conversation in a specific service

`POST /v1/Services/{ChatServiceSid}/Conversations/{ConversationSid}/Participants`

## Request

- Base URL: `https://conversations.twilio.com`
- URL: `https://conversations.twilio.com/v1/Services/{ChatServiceSid}/Conversations/{ConversationSid}/Participants`
- Auth: HTTP basic

Add a new participant to the conversation in a specific service

## Path parameters

- `ChatServiceSid` string, required
- `ConversationSid` string, required

## Headers

- `X-Twilio-Webhook-Enabled` 'true' | 'false'

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

- object
  - `Identity` string: A unique string identifier for the conversation participant as [Conversation User](https://www.twilio.com/docs/conversations/api/user-resource). This parameter is non-null if (and only if) the participant is using the [Conversation SDK](https://www.twilio.com/docs/conversations/sdk-overview) to communicate. Limited to 256 characters.
  - `MessagingBinding.Address` string: The address of the participant's device, e.g. a phone or WhatsApp number. Together with the Proxy address, this determines a participant uniquely. This field (with `proxy_address`) is only null when the participant is interacting from an SDK endpoint (see the `identity` field).
  - `MessagingBinding.ProxyAddress` string: The address of the Twilio phone number (or WhatsApp number) that the participant is in contact with. This field, together with participant address, is only null when the participant is interacting from an SDK endpoint (see the `identity` field).
  - `DateCreated` string, date-time: The date on which this resource was created.
  - `DateUpdated` string, date-time: The date on which this resource was last updated.
  - `Attributes` string: An optional string metadata field you can use to store any data you wish. The string value must contain structurally valid JSON if specified. **Note** that if the attributes are not set `{}` will be returned.
  - `MessagingBinding.ProjectedAddress` string: The address of the Twilio phone number that is used in Group MMS.
  - `RoleSid` string: The SID of a conversation-level [Role](https://www.twilio.com/docs/conversations/api/role-resource) to assign to the participant.

## Response `201`

Created

- ConversationsV1ServiceServiceConversationServiceConversationParticipant
  - `account_sid` string, nullable: The unique ID of the [Account](https://www.twilio.com/docs/iam/api/account) responsible for this participant.
  - `chat_service_sid` string, nullable: The SID of the [Conversation Service](https://www.twilio.com/docs/conversations/api/service-resource) the Participant resource is associated with.
  - `conversation_sid` string, nullable: The unique ID of the [Conversation](https://www.twilio.com/docs/conversations/api/conversation-resource) for this participant.
  - `sid` string, nullable: A 34 character string that uniquely identifies this resource.
  - `identity` string, nullable: A unique string identifier for the conversation participant as [Conversation User](https://www.twilio.com/docs/conversations/api/user-resource). This parameter is non-null if (and only if) the participant is using the [Conversation SDK](https://www.twilio.com/docs/conversations/sdk-overview) to communicate. Limited to 256 characters.
  - `attributes` string, nullable: An optional string metadata field you can use to store any data you wish. The string value must contain structurally valid JSON if specified. **Note** that if the attributes are not set `{}` will be returned.
  - `messaging_binding` unknown
  - `role_sid` string, nullable: The SID of a conversation-level [Role](https://www.twilio.com/docs/conversations/api/role-resource) to assign to the participant.
  - `date_created` string, date-time, nullable: The date on which this resource was created.
  - `date_updated` string, date-time, nullable: The date on which this resource was last updated.
  - `url` string, uri, nullable: An absolute API resource URL for this participant.
  - `last_read_message_index` integer, nullable: Index of last “read” message in the [Conversation](https://www.twilio.com/docs/conversations/api/conversation-resource) for the Participant.
  - `last_read_timestamp` string, nullable: Timestamp of last “read” message in the [Conversation](https://www.twilio.com/docs/conversations/api/conversation-resource) for the Participant.

## Changes

- **2025-07-03** (v1) `92d1169c37c2`: 1 breaking
  - the `messaging_binding` response's property type changed from `object` to no type for status `201`
- **2025-03-11** (v1) `b4d0e634cd69`: 1 breaking
  - the `messaging_binding` response's property type changed from no type to `object` for status `201`
- **2023-08-10** (v1) `4e3f150aaa78`: 1 info
  - api tag `ConversationsV1Participant` added

[Operation history](https://skmtc.dev/twilio/apis/conversations-v1/changes/v1/Services/:ChatServiceSid/Conversations/:ConversationSid/Participants/post.md)

---

[API](https://skmtc.dev/twilio/apis/conversations-v1.md) - [All operations](https://skmtc.dev/twilio/apis/conversations-v1/llms.txt) - [OpenAPI document](https://skmtc.dev/twilio/apis/conversations-v1/revisions/6a37056c7727?raw)