> ## Documentation Index > Fetch the complete documentation index at: https://docs.ycloud.com/llms.txt > Use this file to discover all available pages before exploring further. # Pre-accept a call > Pre-accepts an inbound WhatsApp call. Pre-accepting calls allows the calling media connection to be established before attempting to send call media through the connection. This facilitates faster connection times and avoids audio clipping issues. ## OpenAPI ````yaml /openapi/endpoints/ycloud-api-v2.yaml post /whatsapp/calls/preAccept openapi: 3.0.0 info: description: >- The [YCloud](https://ycloud.com) API is organized around [REST](https://en.wikipedia.org/wiki/Representational_state_transfer). Our API is designed to have predictable, resource-oriented URLs, return [JSON](https://www.json.org) responses, and use standard HTTP response codes and verbs. version: v2 title: YCloud API termsOfService: https://ycloud.com/terms-service contact: email: service@ycloud.com servers: - url: https://api.ycloud.com/v2 description: Base URL security: - api_key: [] tags: - name: Balance - name: Contacts - name: Custom Events - name: Emails - name: SMS - name: Unsubscribers - name: Verify - name: Voices - name: Webhook Endpoints - name: WhatsApp Business Accounts - name: WhatsApp Inbound Messages - name: WhatsApp Media - name: WhatsApp Messages - name: WhatsApp Blocked Users - name: WhatsApp Groups - name: WhatsApp Calling - name: WhatsApp Phone Numbers - name: WhatsApp Templates - name: WhatsApp Flows - name: Meta Business Agent - name: WhatsApp Group Messages externalDocs: description: Homepage url: https://ycloud.com paths: /whatsapp/calls/preAccept: post: tags: - WhatsApp Calling summary: Pre-accept a call description: >- Pre-accepts an inbound WhatsApp call. Pre-accepting calls allows the calling media connection to be established before attempting to send call media through the connection. This facilitates faster connection times and avoids audio clipping issues. operationId: whatsapp_call-pre-accept requestBody: content: application/json: schema: $ref: '#/components/schemas/WhatsappCallingPreAcceptRequest' required: true responses: '200': description: The call pre-accept request is successfully processed. content: application/json: schema: $ref: '#/components/schemas/WhatsappCallingResponse' '400': description: Bad request. Invalid request parameters. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '404': description: The requested resource does not exist. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' components: schemas: WhatsappCallingPreAcceptRequest: type: object required: - phoneId - wacid - sdpType - sdp properties: phoneId: type: string description: The WhatsApp Business phone number ID. example: '461269257068832' wacid: type: string description: >- The WhatsApp call ID. Required for inbound call operations. This ID is received from the Call Connect webhook when a WhatsApp user initiates the call. example: >- wacid.HBgNNjI4MTM2MTkwNTEzMxUCABIYIDhEMjc4NEY2QUU4NTA2MTgxNTBGNzQ3N0M4QTBDMTU5HBgNNjI4MzEzODIwNTE1MBUCABUeAA== sdpType: type: string description: The SDP type for pre-accept operations. Must be "answer". enum: - answer example: answer sdp: type: string description: >- The Session Description Protocol (SDP) information compliant with [RFC 8866](https://datatracker.ietf.org/doc/html/rfc8866). Contains media session parameters for the WebRTC connection. example: "v=0\r\no=- 2239925877841361960 2 IN IP4 127.0.0.1\r\ns=-\r\nt=0 0\r\na=group:BUNDLE audio\r\na=msid-semantic: WMS 0ed5100f-da68-4193-8865-146c1ac7a087\r\nm=audio 9 UDP/TLS/RTP/SAVPF 111 126\r\nc=IN IP4 0.0.0.0\r\na=rtcp:9 IN IP4 0.0.0.0\r\na=ice-ufrag:NCH6\r\na=ice-pwd:ogUYxqJDPNn0C5RFif6UlLz6\r\na=ice-options:trickle\r\na=fingerprint:sha-256 5B:95:C4:E4:8B:2B:06:B6:DB:FB:2C:08:2F:FD:3B:C7:9C:8D:84:4C:97:8D:84:AC:B2:93:32:B8:20:5C:3C:85\r\na=setup:active\r\na=mid:audio\r\na=sendrecv\r\na=msid:0ed5100f-da68-4193-8865-146c1ac7a087 bc955459-4bae-4504-99c8-348944c12b6f\r\na=rtcp-mux\r\na=rtpmap:111 opus/48000/2\r\na=rtcp-fb:111 transport-cc\r\na=fmtp:111 minptime=10;useinbandfec=1\r\na=rtpmap:126 telephone-event/8000\r\na=ssrc:436995058 cname:BIzAP4IgR06SrZ1S\r\n" WhatsappCallingResponse: type: object required: - success properties: wacid: type: string description: The WhatsApp call ID associated with this calling operation. example: >- wacid.HBgNNjI4MTM2MTkwNTEzMxUCABEYIDNENjg2OEMzNTFFRDkwRkUxRUE1RTgxNjY1NjJCQUJBHBgNNjI4MzEzODIwNTE1MBUCABUeAA== success: type: boolean description: Indicates whether the calling operation was successful. example: true ErrorResponse: type: object required: - error properties: error: $ref: '#/components/schemas/Error' description: >- Contains the error code and human-readable message for the API error. Error: type: object required: - status - code properties: status: type: integer format: int32 pattern: '[45]\d{2}' description: >- HTTP status code, [RFC 7231, Section 6](https://datatracker.ietf.org/doc/html/rfc7231#section-6). It conveys the HTTP status code used for the convenience of the consumer. example: 404 code: type: string description: >- One of a server-defined error codes. Some `4xx` errors that could be handled programmatically include an error code that briefly explains the error reported. example: NOT_FOUND message: type: string description: >- A human-readable representation of the error. It is intended as an aid to developers and is not suitable for exposure to end users. example: The requested resource does not exist. target: type: string description: The target of the error. example: '' docUrl: type: string description: A URL to more information about the error. example: '' requestId: type: string description: >- Each API request has an associated request ID. It conveys the response header `YCloud-Request-ID` used for the convenience of the consumer. example: req_1KjtKI80IKoaJNa6n6p whatsappApiError: $ref: '#/components/schemas/WhatsappApiError' description: >- The original error object returned by WhatsApp. See [Handling Errors](https://developers.facebook.com/docs/graph-api/guides/error-handling), [Cloud API Error Codes](https://developers.facebook.com/docs/whatsapp/cloud-api/support/error-codes). Note: This field is returned if we tried to request the WhatsApp Business API and got an error response. metaBusinessAgentApiError: $ref: '#/components/schemas/MetaBusinessAgentApiError' description: >- Sanitized upstream details returned when a Meta Business Agent request fails. WhatsappApiError: type: object description: >- The original error object returned by WhatsApp. See [Handling Errors](https://developers.facebook.com/docs/graph-api/guides/error-handling), [Cloud API Error Codes](https://developers.facebook.com/docs/whatsapp/cloud-api/support/error-codes). required: - message - code properties: message: type: string description: A human-readable description of the error. example: HSM Template creation failed code: type: string description: An error code. example: 200002 type: type: string description: Error type. example: OAuthException is_transient: type: boolean description: Whether the error is transient. example: false error_subcode: type: string description: Additional code about the error. example: 2388109 error_user_msg: type: string description: >- The message to display to the user. The language of the message is based on the locale of the API request. example: This message template cannot be created. error_user_title: type: string description: >- The title of the dialog, if shown. The language of the message is based on the locale of the API request. example: Message Cannot Be Submitted fbtrace_id: type: string description: >- Internal support identifier. When reporting a bug related to a Graph API call, include the fbtrace_id to help us find log data for debugging. example: AVGjJ7ia2zJkrHG error_data: description: >- Additional data about the error. A string or map. - For template APIs, this field is a string describing the reason for the error. - For message APIs, this field is a map with property `details` describing the reason for the error. oneOf: - type: string - type: object additionalProperties: true MetaBusinessAgentApiError: type: object description: Sanitized details from a failed Meta Business Agent upstream request. properties: title: type: string detail: type: string type: type: string status: type: integer format: int32 requestId: type: string securitySchemes: api_key: type: apiKey name: X-API-Key in: header ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.