> ## Documentation Index > Fetch the complete documentation index at: https://docs-classic.cognigy.com/llms.txt > Use this file to discover all available pages before exploring further. # V2V (voice-to-voice) bridge callback > Receives toolCall/transcript/segmentEnded events from the V2V realtime bridge for an in-progress call and forwards them to the owning service-endpoint instance. Not part of the public API - authenticated via the `X-V2V-Token` header (HMAC of `sessionId`) rather than a user session. ## OpenAPI ````yaml https://api-trial.cognigy.ai/openapi/openapi-viewer.json post /v2.0/v2v/callback openapi: 3.0.0 info: title: Cognigy.AI REST-ful-API Reference version: 2026.23.0 description: > ### Introduction This is the [OpenAPI 3.0](https://swagger.io/specification/) documentation of the [REST](https://en.wikipedia.org/wiki/Representational_state_transfer)-ful Cognigy.AI API. ### Cross-Origin Resource Sharing This API features Cross-Origin Resource Sharing (CORS) implemented in compliance with [W3C spec](https://www.w3.org/TR/cors/), which allows cross-domain communication from the browser. All responses include a wildcard same-origin header, making the API fully accessible. ### Authentication Cognigy.AI offers three forms of authentication: - API Key - CXone Token - BasicAuth An API Key is a security token. You can use API Keys in your path or HTTP header. Never expose your API Key and keep it safe and secure. Revoke the API Key if it got exposed or stolen. Basic Auth is only used for API calls regarding the Management-UI. ### Error Handling This API uses HTTP status codes equal or above 400 to indicate errors. Error details are generated in compliance with [RFC 7807 - "Problem Details for HTTP APIs"](https://tools.ietf.org/html/rfc7807). Every error response contains a traceId, which should be provided to the Cognigy.AI Technical Support when reporting an error. contact: name: Cognigy Technical Support url: https://www.cognigy.com email: support@cognigy.com servers: - url: https://api-trial.cognigy.ai/new/ description: Cognigy.AI API security: - APIKeyHeader: [] - APIKeyQueryParam: [] - CXoneTokenHeader: [] - BasicAuth: [] tags: - name: Cognigy.AI REST-ful API description: The Cognigy.AI REST-ful API externalDocs: description: Cognigy.AI Documentation url: https://docs.cognigy.com/docs/ paths: /v2.0/v2v/callback: post: tags: - V2V summary: V2V (voice-to-voice) bridge callback description: > Receives toolCall/transcript/segmentEnded events from the V2V realtime bridge for an in-progress call and forwards them to the owning service-endpoint instance. Not part of the public API - authenticated via the `X-V2V-Token` header (HMAC of `sessionId`) rather than a user session. operationId: v2vCallback_2_0 parameters: - in: header name: X-V2V-Token required: true schema: type: string responses: '202': description: >- Event accepted and forwarded, or silently dropped (no service-endpoint replica currently owns this bridge sessionId). '400': description: Malformed body. '401': description: Missing or invalid X-V2V-Token header. '402': description: Upgrade your Plan to increase your Quota. content: application/json: schema: type: object properties: type: type: string example: Payment Required title: type: string example: Payment Required Error status: type: number example: 402 detail: type: string example: Validation failed. Missing payload. instance: type: string example: /v2.0/flows/5ce7c2d833ea1e04d7e6c432 code: type: string example: 402 traceId: type: string example: api--f84324f4-98eb-4f02-abdd-375a2e6c3c1f details: type: object example: {} '403': description: The server understood the request but refuses to authorize it. content: application/json: schema: type: object properties: type: type: string example: Forbidden title: type: string example: Forbidden Error status: type: number example: 403 detail: type: string instance: type: string example: /v2.0/flows/5ce7c2d833ea1e04d7e6c432 code: type: string example: 1000 traceId: type: string example: api--f84324f4-98eb-4f02-abdd-375a2e6c3c1f details: type: object example: {} '404': description: >- The origin server did not find a current representation for the target resource or is not willing to disclose that one exists. content: application/json: schema: type: object properties: type: type: string example: Not Found title: type: string example: Not Found Error status: type: number example: 404 detail: type: string instance: type: string example: /v2.0/flows/5ce7c2d833ea1e04d7e6c432 code: type: string example: 1000 traceId: type: string example: api--f84324f4-98eb-4f02-abdd-375a2e6c3c1f details: type: object example: {} logLevel: type: string example: error '405': description: >- The method received in the request-line is known by the origin server but not supported by the target resource. content: application/json: schema: type: object properties: type: type: string example: Method Not Allowed title: type: string example: Method Not Allowed Error status: type: number example: 405 detail: type: string instance: type: string example: /v2.0/flows/5ce7c2d833ea1e04d7e6c432 code: type: string example: 1000 traceId: type: string example: api--f84324f4-98eb-4f02-abdd-375a2e6c3c1f details: type: object example: {} '409': description: The request conflicts with current state of the server. content: application/json: schema: type: object properties: type: type: string example: Conflict title: type: string example: Conflict Error status: type: number example: 409 detail: type: string instance: type: string example: /v2.0/flows/5ce7c2d833ea1e04d7e6c432 code: type: string example: 1004 traceId: type: string example: api--f84324f4-98eb-4f02-abdd-375a2e6c3c1f details: type: object example: {} '413': description: The request entity is larger than limits defined by server. content: application/json: schema: type: object properties: type: type: string example: Payload Too Large title: type: string example: Payload Too Large Error status: type: number example: 413 detail: type: string instance: type: string example: /v2.0/flows/5ce7c2d833ea1e04d7e6c432 code: type: string example: 1000 traceId: type: string example: api--f84324f4-98eb-4f02-abdd-375a2e6c3c1f details: type: object example: {} '500': description: >- The server encountered an unexpected condition that prevented it from fulfilling the request. content: application/json: schema: type: object properties: type: type: string example: Internal Server Error title: type: string example: Internal Server Error status: type: number example: 500 detail: type: string instance: type: string example: /v2.0/flows/5ce7c2d833ea1e04d7e6c432 code: type: string example: 1000 traceId: type: string example: api--f84324f4-98eb-4f02-abdd-375a2e6c3c1f details: type: object example: {} '501': description: >- The server does not support the functionality required to fulfill the request. content: application/json: schema: type: object properties: type: type: string example: Not Implemented title: type: string example: Not Implemented Error status: type: number example: 501 detail: type: string instance: type: string example: /v2.0/flows/5ce7c2d833ea1e04d7e6c432 code: type: string example: 1009 traceId: type: string example: api--f84324f4-98eb-4f02-abdd-375a2e6c3c1f details: type: object example: {} '502': description: >- The server, while acting as a gateway or proxy, received an invalid response from an inbound server it accessed while attempting to fulfill the request. content: application/json: schema: type: object properties: type: type: string example: Bad Gateway title: type: string example: Bad Gateway Error status: type: number example: 502 detail: type: string instance: type: string example: /v2.0/flows/5ce7c2d833ea1e04d7e6c432 code: type: string example: 1000 traceId: type: string example: api--f84324f4-98eb-4f02-abdd-375a2e6c3c1f details: type: object example: {} '503': description: >- V2V_CALLBACK_SECRET is not configured on this instance, or the event could not be forwarded (Redis or broker unavailable); retryable. '504': description: >- The server, while acting as a gateway or proxy, did not receive a timely response from an upstream server it needed to access in order to complete the request. content: application/json: schema: type: object properties: type: type: string example: Gateway Timeout title: type: string example: Gateway Timeout Error status: type: number example: 504 detail: type: string instance: type: string example: /v2.0/flows/5ce7c2d833ea1e04d7e6c432 code: type: string example: 1000 traceId: type: string example: api--f84324f4-98eb-4f02-abdd-375a2e6c3c1f details: type: object example: {} security: - APIKeyHeader: [] - APIKeyQueryParam: [] - CXoneTokenHeader: [] components: securitySchemes: APIKeyHeader: type: apiKey in: header name: X-API-Key description: Supply the API Key in the HTTP-Header APIKeyQueryParam: type: apiKey in: query name: api_key description: Supply the API Key in the Url-Query CXoneTokenHeader: type: apiKey in: header name: x-cxone-authorization description: >- Supply the CXone Token in the HTTP-Header containing the word "Bearer" followed by a space and a Token String. Applicable only in CXone integrated environments. BasicAuth: type: http scheme: basic description: Basic Authentication used by routes designed for the Management-UI. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.