> ## Documentation Index > Fetch the complete documentation index at: https://developers.telnyx.com/llms.txt > Use this file to discover all available pages before exploring further. # Assistant WhatsApp Chat > Start a WhatsApp conversation with a customer from the business side. This endpoint: 1. Validates that `from` is a WhatsApp number on your account whose messaging profile has this assistant configured 2. Creates a new `whatsapp_chat` conversation with the provided metadata 3. Asks the assistant to pick one of its approved WhatsApp templates and fill its variables from `content` 4. Sends the template from `from` to `to` 5. Returns the conversation ID and the message ID When the customer replies, the reply is routed to the same conversation and the assistant answers within the 24-hour customer service window. The assistant needs a `whatsapp_template` tool with at least one approved template, data retention enabled and PII redaction disabled. ## OpenAPI ````yaml /openapi/source/external/inference/inference-embedding.json post /ai/assistants/{assistant_id}/chat/whatsapp openapi: 3.1.0 info: version: 2.0.0 title: Telnyx API x-latency-category: responsive x-endpoint-cost: light description: SIP trunking, SMS, MMS, Call Control and Telephony Data Services. contact: email: support@telnyx.com servers: - url: https://api.telnyx.com/v2 description: Version 2.0.0 of the Telnyx API security: - bearerAuth: [] tags: - name: Chat description: Generate text with LLMs - name: Assistants description: Configure AI assistant specifications - name: Conversations description: Manage historical AI assistant conversations - name: File-based Text-to-Speech description: Turn audio into text or text into audio. - name: Embeddings description: Embed documents and perform text searches - name: Clusters description: Identify common themes and patterns in your embedded documents - name: Fine Tuning description: Customize LLMs for your unique needs - name: OpenAI Embeddings description: >- OpenAI-compatible embeddings endpoints for generating vector representations of text paths: /ai/assistants/{assistant_id}/chat/whatsapp: post: tags: - Assistants summary: Assistant WhatsApp Chat description: >- Start a WhatsApp conversation with a customer from the business side. This endpoint: 1. Validates that `from` is a WhatsApp number on your account whose messaging profile has this assistant configured 2. Creates a new `whatsapp_chat` conversation with the provided metadata 3. Asks the assistant to pick one of its approved WhatsApp templates and fill its variables from `content` 4. Sends the template from `from` to `to` 5. Returns the conversation ID and the message ID When the customer replies, the reply is routed to the same conversation and the assistant answers within the 24-hour customer service window. The assistant needs a `whatsapp_template` tool with at least one approved template, data retention enabled and PII redaction disabled. operationId: assistant_whatsapp_chat_assistants__assistant_id__chat_whatsapp_post parameters: - name: assistant_id in: path description: >- Unique identifier of the assistant. Must be the assistant configured on the messaging profile of the `from` number. required: true schema: type: string title: Assistant Id - $ref: '#/components/parameters/IdempotencyKey' requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/AssistantWhatsappChatReq' example: from: '+13125550001' to: '+13125550002' content: Send the login verification code 482913 to the customer. conversation_metadata: order_id: A1 responses: '200': description: Successful Response content: application/json: schema: $ref: '#/components/schemas/AssistantWhatsappChatResponse' example: conversation_id: 59f1f39e-180c-4f5d-81e9-393b46ca4077 message_id: 4031a0e8-f724-4e22-a086-0f18720ac829 headers: Idempotent-Replayed: $ref: '#/components/headers/IdempotentReplayed' '400': description: >- Bad Request. Missing required fields or a reserved `conversation_metadata` key, or the assistant is not the one configured on the messaging profile of `from` (10015). Invalid JSON (10023). A field of the wrong type, for example a non-string `from`, `to` or `content`, or a `conversation_metadata` value that is not a string, integer or boolean (10026). `from` is not a valid WhatsApp number on a messaging profile (40305). `to` is not a valid E.164 number or BSUID (40310). Invalid, duplicate, empty, malformed, or overlong Idempotency-Key headers are rejected by Edge with HTTP 400 and error code 10015. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '401': description: Authentication Failed (10009). The API key is missing or invalid. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '403': description: >- Forbidden. The `from` number is not associated with your account (10010), messaging is disabled on the account (40314), or the account is inactive (20012), blocked (20013) or unverified (20014). content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '404': description: Not Found (10005). The assistant does not exist. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '409': description: >- Conflict. The messaging profile of `from` is disabled (40312), or a request with the same Idempotency-Key is still being processed (10036), in which case retry later with the same key and request. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: errors: - code: '10036' title: Resource is being processed detail: >- A request with this Idempotency-Key is already being processed. source: pointer: /header/Idempotency-Key '413': description: >- Payload Too Large. A request sent with an Idempotency-Key whose body exceeds the endpoint's Edge replay-protection limit (256 KB) is rejected before it reaches the service. Requests sent without the header are not subject to this limit. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '422': description: >- Unprocessable Entity (10027). The assistant did not return a WhatsApp template, or its privacy settings do not allow storing conversations. Reusing an Idempotency-Key with a different request body also returns 422 with error code 10027. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '503': description: >- Service Unavailable (10037). The assistant could not be looked up, the conversation could not be started, or the template could not be sent. Retry the request. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' components: parameters: IdempotencyKey: name: Idempotency-Key in: header required: false description: >- Optional opaque, unquoted key for safely retrying the same logical request. Keys must contain 1 to 255 letters, numbers, hyphens, or underscores. Generate a unique UUID v4 for each operation and reuse it only when retrying that operation with the same request. Invalid headers—including duplicate, empty, malformed, or overlong values—return 400 with error code 10015. A request already in progress with the same key returns 409; reusing the key with a different request returns 422. Only successful responses are replayed, for up to 24 hours. Do not include sensitive data in the key. schema: type: string minLength: 1 maxLength: 255 pattern: ^[A-Za-z0-9_-]{1,255}$ example: 8e03978e-40d5-43e8-bc93-6894a57f9326 schemas: AssistantWhatsappChatReq: properties: from: type: string title: From description: >- WhatsApp number on your account to send from, in E.164 format. Its messaging profile must have this assistant configured. to: type: string title: To description: >- Customer to message, as an E.164 phone number or a WhatsApp business-scoped user ID (BSUID). content: type: string title: Content description: >- Instruction for the assistant, including the values for the template variables, e.g. `Send the login verification code 482913 to the customer.` conversation_metadata: title: Conversation Metadata description: >- Metadata stored on the conversation. Keys starting with `telnyx_` and the `assistant_id` key are reserved. additionalProperties: anyOf: - type: string - type: integer - type: boolean type: object type: object required: - from - to - content title: AssistantWhatsappChatReq AssistantWhatsappChatResponse: properties: conversation_id: title: Conversation Id type: string description: ID of the conversation created for this WhatsApp chat. message_id: title: Message Id type: string description: ID of the WhatsApp template message that was sent. type: object required: - conversation_id - message_id title: AssistantWhatsappChatResponse ErrorResponse: type: object properties: errors: type: array items: $ref: '#/components/schemas/ErrorObject' required: - errors ErrorObject: type: object properties: code: type: string description: >- Telnyx error code. Edge idempotency errors use 10015, 10027, or 10036; idempotency protection outages use 10016; replay-cap 413s surface 10007. Fallback 404/500 responses from the framework may use string status codes ('404', '500') instead. enum: - '10007' - '10015' - '10016' - '10027' - '10036' - '404' - '500' title: type: string detail: type: string source: type: object properties: pointer: type: string required: - code - title headers: IdempotentReplayed: description: >- Present with value `true` when Edge replayed a stored successful response for the supplied Idempotency-Key. Omitted for first-time requests and error responses. schema: type: boolean enum: - true example: true securitySchemes: bearerAuth: type: http scheme: bearer ````