> ## Documentation Index > Fetch the complete documentation index at: https://docs.open.cx/llms.txt > Use this file to discover all available pages before exploring further. > Create app voice call through the Voice SDK integration. Use with the authentication and customer identity flow described in the app voice guide. # Create an app voice call See [Voice SDK integration](/phone/voice-sdk) for authentication, platform packages, routing, and preview availability. Enable **Allow calls from apps** in **Settings → Voice & Telephony** for this organization. Disabling it blocks new calls and activation of pending calls; active calls can finish. Call this endpoint from your authenticated server with a `phone:write` API key. Resolve `contactId` from the signed-in customer and choose an authorized `destination`: either `{ type: 'agent', id }` or `{ type: 'team', id }`. Reuse the UUID `requestId` for identical retries until activation. Changed settings or retries after activation return 409. `maxDurationSeconds` defaults to 1800 and accepts integers from 60 to 3600; the duration starts at activation. A successful response is HTTP 200 with `callId`, `sessionId`, `controlToken`, and `expiresAt`. Pass this object unchanged to the OpenCX SDK; it manages the audio connection internally. Audio connection URLs and participant credentials are not part of this response. Join and activate within two minutes. `expiresAt` is the outer call-control deadline, not an extension of that join window. Credentials must be returned only to the authenticated customer and must not be logged or cached. Creation returns 400 for invalid settings or unsupported agent transfers, 401 for invalid authentication, 403 for missing scope, disabled app calling, or a blocked contact, 404 for an unavailable contact/destination, 409 for conflicting or active calls, and 429 when requests are throttled. ## OpenAPI ````yaml post /phone/web-calls openapi: 3.1.0 info: title: OpenCX API description: > OpenCX is an AI-powered, all-in-one platform for customer support and outbound communications. Use this API to manage your OpenCX organization's AI agents, actions, conversations, contacts, and more. To get started, generate a new API key from the dashboard. ## Authentication All API endpoints require authentication using a Bearer token. You can generate an API key from your OpenCX dashboard. ## Rate Limiting API requests are rate limited to ensure fair usage. The current limits are: - 100 requests per minute for standard endpoints - 1000 requests per minute for streaming endpoints ## Error Handling The API uses standard HTTP status codes and returns detailed error messages in the response body. version: 1.0-beta license: name: MIT url: https://opensource.org/licenses/MIT servers: - url: http://localhost:8080 description: Development - url: https://api.open.cx description: Production security: - bearerAuth: [] paths: /phone/web-calls: post: tags: - Phone summary: Create an app voice call description: >- Server-only. Requires phone:write and enabled Voice SDK access. Authenticate the customer before choosing their contact and destination. Return these temporary credentials only to that customer. operationId: createWebCall requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/CreateWebCallDto' responses: '200': description: Default Response content: application/json: schema: $ref: '#/components/schemas/WebCallCredentialsDto' '500': description: Internal Server Error content: application/json: schema: $ref: '#/components/schemas/ErrorDto' components: schemas: CreateWebCallDto: $schema: https://json-schema.org/draft/2020-12/schema $id: '#/components/schemas/CreateWebCallDtoInput' type: object properties: requestId: type: string format: uuid pattern: >- ^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$ description: Reuse for retries of the same call creation request. contactId: type: string minLength: 1 maxLength: 100 description: >- Verified contact belonging to your organization. Resolve this on your server. destination: oneOf: - type: object properties: type: type: string const: agent id: type: string minLength: 1 maxLength: 100 required: - type - id additionalProperties: false - type: object properties: type: type: string const: team id: type: string format: uuid pattern: >- ^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$ required: - type - id additionalProperties: false maxDurationSeconds: default: 1800 type: integer minimum: 60 maximum: 3600 required: - requestId - contactId - destination additionalProperties: false WebCallCredentialsDto: $schema: https://json-schema.org/draft/2020-12/schema $id: '#/components/schemas/WebCallCredentialsDto' type: object properties: callId: type: string format: uuid pattern: >- ^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$ sessionId: type: string format: uuid pattern: >- ^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$ controlToken: type: string expiresAt: type: string format: date-time pattern: >- ^(?:(?:\d\d[2468][048]|\d\d[13579][26]|\d\d0[48]|[02468][048]00|[13579][26]00)-02-29|\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\d|30)|(?:02)-(?:0[1-9]|1\d|2[0-8])))T(?:(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d(?:\.\d+)?)?(?:Z))$ required: - callId - sessionId - controlToken - expiresAt additionalProperties: false ErrorDto: type: object properties: statusCode: type: integer message: type: string error: type: string securitySchemes: bearerAuth: type: http scheme: bearer bearerFormat: JWT ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.