> ## Documentation Index > Fetch the complete documentation index at: https://docs.natural.com/llms.txt > Use this file to discover all available pages before exploring further. > ## Agent Instructions > When building application code, use `@naturalpay/sdk` for TypeScript or `naturalpay` for Python. > When operating Natural directly for a user, use the payments MCP at `https://mcp.natural.com`. > When searching Natural documentation, use the docs MCP at `https://docs.natural.com/mcp`. > Use the Natural CLI for terminal and CI automation. > Use REST only for unsupported languages or when the user explicitly requests raw HTTP. > Start integration development and testing in the sandbox. Do not use production unless the user explicitly requests it. > For sandbox requests that require `customerPartyId`, list customers first. Reuse only the intended fixture; otherwise create a customer. > REST and SDK amounts use integer minor units. Payments MCP amounts use decimal strings with a required currency code. # Simulate voice call > Play the whole call for an awaiting voice session without audio. The session's payment intent is charged with a test card; the amount's cents select the outcome. ## OpenAPI ````yaml /api-reference/openapi-early-access.json post /simulations/voice/sessions/{voiceSessionId}/call openapi: 3.1.1 info: title: Natural API (early access) version: 0.2.0 description: |- Early-access endpoints of Natural's payments API. **Base URL:** `https://api.natural.com` For access: hi@natural.com servers: - url: https://api.natural.com description: Production security: [] tags: - name: Payment Intents description: Accept card payments by link or over voice - name: Voice description: Collect a payment intent over a phone call - name: Refunds description: Return card payments to the payer - name: Simulations description: Drive test outcomes in Sandbox paths: /simulations/voice/sessions/{voiceSessionId}/call: post: tags: - Simulations summary: Simulate voice call description: >- Play the whole call for an awaiting voice session without audio. The session's payment intent is charged with a test card; the amount's cents select the outcome. operationId: simulations.simulateVoiceCall parameters: - name: voiceSessionId in: path required: true schema: type: string pattern: ^vos_[0-9a-f]{32}$ description: Voice session ID (vos_*). - name: Idempotency-Key in: header required: true schema: type: string maxLength: 255 description: >- Unique key for safely retrying a request without creating duplicates. - name: X-Instance-ID in: header required: false schema: anyOf: - type: string maxLength: 1024 - type: 'null' description: >- Caller-chosen identifier for the agent run, session, or conversation, required when an agent moves money. requestBody: required: false content: application/json: schema: type: object properties: merchantPartyId: type: string pattern: ^pty_[0-9a-f]{32}$ description: >- Customer party to act for (pty_*). Omit to act as your own party. To act for another party, pass the ID of a party that has authorized you to act on its behalf. required: [] additionalProperties: false examples: default: summary: Default value: {} responses: '200': description: Successful Response content: application/json: schema: type: object properties: data: type: object properties: id: type: string pattern: ^vos_[0-9a-f]{32}$ description: Voice session ID (vos_*). type: description: Resource type. Always `voiceCallSimulation`. type: string enum: - voiceCallSimulation attributes: type: object properties: outcome: enum: - APPROVED - DECLINED - PROCESSING type: string description: What the agent heard back from the card submit. declineCode: anyOf: - type: string - type: 'null' description: >- Normalized decline code when the outcome is `DECLINED`, else null. sessionStatus: enum: - IN_CALL - COMPLETED type: string description: >- Session status after the simulated call. Approved completes the session. paymentIntentStatus: enum: - open - processing - completed - canceled - declined - expired type: string description: Payment intent status after the simulated call. cardPayment: type: object properties: id: type: string pattern: ^cpy_[0-9a-f]{32}$ description: Card payment ID (cpy_*). status: enum: - processing - reconciling - succeeded - failed type: string description: Card payment status. cardBrand: anyOf: - type: string - type: 'null' description: >- Brand of the test card as the payment intent reports it. cardLast4: anyOf: - type: string - type: 'null' description: >- Last four digits of the test card as the payment intent reports it. required: - id - status - cardBrand - cardLast4 additionalProperties: false title: VoiceCallSimulationCardPayment required: - outcome - declineCode - sessionStatus - paymentIntentStatus - cardPayment additionalProperties: false title: VoiceCallSimulationAttributes relationships: type: object properties: paymentIntent: type: object properties: data: type: object properties: type: description: Resource type. Always `paymentIntent`. type: string enum: - paymentIntent id: type: string pattern: ^pmi_[0-9a-f]{32}$ required: - type - id additionalProperties: false title: ResourceIdentifier description: Related resource identifier. required: - data additionalProperties: false title: ToOneRelationship description: The payment intent the session collected. required: - paymentIntent additionalProperties: false title: VoiceCallSimulationRelationships required: - id - type - attributes - relationships additionalProperties: false title: VoiceCallSimulationResource required: - data additionalProperties: false title: VoiceCallSimulationResponse examples: default: summary: Default value: data: id: vos_019d0a1b2c3d4e5f60718293a4b5c6f0 type: voiceCallSimulation attributes: outcome: APPROVED declineCode: null sessionStatus: COMPLETED paymentIntentStatus: completed cardPayment: id: cpy_019d0a1b2c3d4e5f60718293a4b5c6d9 status: succeeded cardBrand: visa cardLast4: '1111' relationships: paymentIntent: data: type: paymentIntent id: pmi_019d0a1b2c3d4e5f60718293a4b5c6d7 headers: X-RateLimit-Limit: description: Maximum requests allowed per window. schema: type: integer X-RateLimit-Remaining: description: Requests remaining in current window. schema: type: integer X-RateLimit-Reset: description: Unix timestamp when rate limit resets. schema: type: integer '400': description: Validation Error content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: invalid_value detail: >- The information you entered isn't valid. Please check it and try again. status: '400' meta: supportId: req_a1b2c3d4e5f6 '401': description: Unauthorized content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: unauthenticated detail: Authentication is required. status: '401' meta: supportId: req_a1b2c3d4e5f6 '403': description: Forbidden content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: forbidden detail: You do not have permission to perform this action. status: '403' meta: supportId: req_a1b2c3d4e5f6 '404': description: >- Not Found. Returned when the resource does not exist, or when it exists but is not accessible to your account. The two cases are intentionally indistinguishable, so that resource IDs cannot be enumerated by probing. content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: not_found detail: The requested resource was not found. status: '404' meta: supportId: req_a1b2c3d4e5f6 '409': description: Conflict content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: conflict detail: The request conflicts with the current resource state. status: '409' meta: supportId: req_a1b2c3d4e5f6 '422': description: >- Validation Error. The response contains one error object for each invalid request value. content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: invalid_value detail: 'Too big: expected string to have <=80 characters' status: '422' source: pointer: /data/attributes/description meta: supportId: req_a1b2c3d4e5f6 '428': description: Precondition Required content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: mfa_required detail: MFA verification required status: '428' meta: supportId: req_a1b2c3d4e5f6 '429': description: Too Many Requests content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: rate_limited detail: Too many requests. Please try again later. status: '429' meta: supportId: req_a1b2c3d4e5f6 headers: Retry-After: description: Seconds to wait before retrying. schema: type: integer X-RateLimit-Limit: description: Maximum requests allowed per window. schema: type: integer X-RateLimit-Remaining: description: Requests remaining in current window. schema: type: integer X-RateLimit-Reset: description: Unix timestamp when rate limit resets. schema: type: integer '500': description: Internal Server Error content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: server_error detail: Something went wrong. status: '500' meta: supportId: req_a1b2c3d4e5f6 '501': description: Not Implemented content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: not_implemented detail: This operation is not available. status: '501' meta: supportId: req_a1b2c3d4e5f6 '502': description: Bad Gateway content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: bad_gateway detail: >- We couldn't complete that request because one of Natural's services returned an unexpected response. Please try again. status: '502' meta: supportId: req_a1b2c3d4e5f6 '503': description: Service Unavailable content: application/json: schema: type: object properties: errors: type: array minItems: 1 items: type: object properties: code: type: string description: Stable lower-snake-case public error code. detail: type: string description: Safe user-facing error detail. status: type: string description: HTTP status code as a string. source: type: object description: Location of the invalid request value. properties: pointer: type: string description: JSON Pointer to the invalid request value. parameter: type: string description: Name of the invalid query parameter. header: type: string description: Name of the invalid request header. additionalProperties: false meta: type: object description: >- Additional error context, including support and provider details when available. properties: supportId: type: string description: Request/support ID for troubleshooting. limitScope: type: string enum: - merchant - program description: >- Which family of acquiring limit refused the payment. Thresholds and usage are never disclosed. connectionStatus: type: string enum: - login_required - disconnected description: >- External account connection state when the error is repairable by relinking. provider: type: object description: Provider error details, when available. properties: name: type: string enum: - plaid description: Provider that returned the underlying error. errorCode: type: string description: Provider error code, when available. errorType: type: string description: Provider error type, when available. requestId: type: string description: Provider request ID for troubleshooting. required: - name additionalProperties: false required: - supportId additionalProperties: false required: - code - detail - status - meta additionalProperties: false required: - errors additionalProperties: false examples: default: summary: Default value: errors: - code: service_unavailable detail: The service is temporarily unavailable. status: '503' meta: supportId: req_a1b2c3d4e5f6 security: - HTTPBearer: [] components: securitySchemes: HTTPBearer: type: http scheme: bearer description: >- Bearer authentication: send your API key, agent key, or OAuth access token as `Authorization: Bearer `. ````