> ## Documentation Index > Fetch the complete documentation index at: https://docs.answeringagent.com/llms.txt > Use this file to discover all available pages before exploring further. # Reply to a conversation > Send a text or email reply to the customer on an existing conversation, the same as clicking Send in the dashboard. The customer receives it. Reply only on a channel in the conversation's channels. Website chats and calls with neither text nor email in channels cannot get a reply. The key's creator must be allowed to message the customer in the dashboard. A customer who opted out by replying STOP gets no texts, but email still sends. The reply goes only to the conversation's customer. The reply shows in the thread and Activity under the key's creator. A failed send still returns 201 with delivery_status failed. Requests from this playground go to production and message a real customer. Customer API. ## OpenAPI ````yaml /openapi.yaml post /conversations/{conversation_id}/messages openapi: 3.0.0 info: title: Answering Agent API description: > The Customer API reads a team's conversations, transcripts, recordings, tasks, contacts, and reports. It also updates tasks, adds notes to them, and replies to customers on existing conversations. The Partner API lets reseller accounts manage organizations, users, locations, partner links, and embed tokens. Both use an X-API-KEY header. Requests from this playground go to production. version: 1.0.0 servers: - url: https://answeringagent.com/api/v1 description: Production security: [] tags: - name: Account description: Customer API. Your team, phone lines, and members. - name: Conversations description: >- Customer API. Calls, texts, website chats, and emails, with transcripts and recordings. Reply to customers by text or email. - name: Tasks description: >- Customer API. Follow-up tasks. Read them, update their status or assignee, and add notes. - name: Contacts description: Customer API. Your customers. - name: Reports description: Customer API. Report metrics, totals, and breakdowns. - name: Organizations description: Partner API, reseller accounts only. - name: Users description: Partner API, reseller accounts only. - name: Locations description: Partner API, reseller accounts only. - name: Account Linking description: Partner API, reseller accounts only. - name: Embed Tokens description: Partner API, reseller accounts only. paths: /conversations/{conversation_id}/messages: post: tags: - Conversations summary: Reply to a conversation description: > Send a text or email reply to the customer on an existing conversation, the same as clicking Send in the dashboard. The customer receives it. Reply only on a channel in the conversation's channels. Website chats and calls with neither text nor email in channels cannot get a reply. The key's creator must be allowed to message the customer in the dashboard. A customer who opted out by replying STOP gets no texts, but email still sends. The reply goes only to the conversation's customer. The reply shows in the thread and Activity under the key's creator. A failed send still returns 201 with delivery_status failed. Requests from this playground go to production and message a real customer. Customer API. operationId: replyToConversation parameters: - $ref: '#/components/parameters/ConversationId' - in: header name: Idempotency-Key required: false schema: type: string pattern: ^[A-Za-z0-9._:-]{1,120}$ example: cancel-confirm-184532 description: > The same as idempotency_key in the body. Send one or the other. Sending both returns 400. requestBody: required: true content: application/json: schema: type: object additionalProperties: false required: - body properties: channel: type: string enum: - text - email description: > One of the conversation's channels. Leave it out only when channels has exactly one of text and email. body: type: string minLength: 1 maxLength: 5000 description: > The message, 1 to 5,000 characters after leading and trailing spaces are removed. An email reply uses the thread's subject. A text longer than 10 SMS segments returns 422. idempotency_key: type: string pattern: ^[A-Za-z0-9._:-]{1,120}$ description: > Scoped to the API key's creator and one conversation. A retry with the same idempotency key on the same conversation, from any API key that person created, returns the first message and sends nothing. Reusing the key with a different body or channel returns 409. example: channel: text body: >- Hi Dana, your membership is cancelled and there is no charge on the 12th. idempotency_key: cancel-confirm-184532 responses: '201': description: > The reply was accepted. Check delivery_status to see whether it went out. A retry with the same idempotency key returns the first message. content: application/json: schema: $ref: '#/components/schemas/ConversationMessage' '400': $ref: '#/components/responses/CustomerBadRequest' '401': $ref: '#/components/responses/CustomerUnauthorized' '403': description: The key's creator cannot message this customer in the dashboard. content: application/json: schema: $ref: '#/components/schemas/CustomerError' '404': $ref: '#/components/responses/CustomerNotFound' '405': $ref: '#/components/responses/CustomerMethodNotAllowed' '409': description: > The idempotency key was already used on this conversation for a different body or channel, and nothing was sent. Rarely, a 409 means the send started but its result could not be saved, so the text or email may have gone out. Check the conversation thread in the dashboard before you send it again. content: application/json: schema: $ref: '#/components/schemas/CustomerError' '422': description: > The dashboard would refuse the same reply. Nothing was sent. The error gives the reason, such as no text or email thread on this conversation, a customer who opted out of texts, a text that is too long, or texting that is not set up. content: application/json: schema: $ref: '#/components/schemas/CustomerError' '429': description: > More than 120 API requests in a minute for this user returns "Too many requests. Try again in N seconds." More than 20 replies in a minute from this user, or more than 5 replies in a minute on this conversation, returns "Too many replies. Try again in N seconds." headers: Retry-After: description: Seconds to wait before retrying. schema: type: integer content: application/json: schema: $ref: '#/components/schemas/CustomerError' security: - ApiKeyAuth: [] components: parameters: ConversationId: in: path name: conversation_id required: true schema: type: integer minimum: 1 description: The conversation ID. schemas: ConversationMessage: type: object required: - id - conversation_id - from - channel - text - sent_at - delivery_status - error properties: id: type: integer example: 7730514 conversation_id: type: integer example: 184532 from: type: string enum: - business channel: type: string enum: - text - email example: text text: type: string example: >- Hi Dana, your membership is cancelled and there is no charge on the 12th. sent_at: type: string format: date-time example: '2026-10-06T15:04:52.000Z' delivery_status: type: string enum: - queued - sent - delivered - failed - unknown example: queued description: > queued means the carrier accepted the reply and has not sent it yet. failed means the send failed and error says why. unknown means the provider did not answer, so check the conversation later. error: type: string nullable: true example: null description: A plain reason when the send failed. Otherwise null. CustomerError: type: object required: - error - code properties: error: type: string description: A message for people. The text can change. example: That conversation is not available. code: type: string description: A stable code to branch on. enum: - invalid_request - unauthorized - forbidden - not_found - method_not_allowed - conflict - unprocessable - rate_limited - internal example: not_found issues: type: array description: >- Present when code is invalid_request. One entry for each input that failed validation. items: type: object properties: path: type: array items: {} message: type: string responses: CustomerBadRequest: description: An input is missing or invalid. content: application/json: schema: $ref: '#/components/schemas/CustomerError' CustomerUnauthorized: description: >- The X-API-KEY header is missing, the key is wrong or revoked, or its owner was deactivated. content: application/json: schema: $ref: '#/components/schemas/CustomerError' CustomerNotFound: description: The record does not exist, or the key's owner cannot see it. content: application/json: schema: $ref: '#/components/schemas/CustomerError' CustomerMethodNotAllowed: description: The endpoint does not support that HTTP method. Nothing changed. headers: Allow: description: The methods the endpoint supports, such as GET, HEAD, OPTIONS. schema: type: string content: application/json: schema: $ref: '#/components/schemas/CustomerError' example: error: This endpoint accepts GET. code: method_not_allowed securitySchemes: ApiKeyAuth: type: apiKey in: header name: X-API-KEY ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.