Telnyx Speech To Text Capabilities API

openapi: 3.2.0
info:
  version: 2.0.0
  x-latency-category: responsive
  x-endpoint-cost: light
  title: Telnyx Speech To Text Capabilities API
  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: Speech To Text Capabilities
  description: Discover available speech-to-text providers, models, and supported languages.
paths:
  /speech-to-text/providers:
    get:
      summary: List supported STT providers
      description: 'Retrieve the canonical list of supported speech-to-text providers, models, accepted language codes, and the service types each model supports.


        Service types:

        * `streaming` — standalone WebSocket transcription via `/speech-to-text/transcription`.

        * `file_based` — file-based transcription via `/ai/audio/transcriptions`.

        * `in_call` — live call transcription via Call Control `transcription_start`.

        * `ai_assistant` — STT configured on a Call Control AI Assistant via voice-assistant `TranscriptionConfig` (covers both live-streaming and non-streaming/batch models).


        Use this endpoint to discover which (provider, model) combinations are available for the surface you need, and which language codes each accepts. `auto` in a `languages` array indicates the provider performs language detection.'
      operationId: listSttProviders
      servers:
      - url: https://api.telnyx.com/v2
        description: Telnyx API v2
      tags:
      - Speech To Text Capabilities
      parameters:
      - name: service_type
        in: query
        required: false
        description: Filter to entries that support the given service type. For backward compatibility with the values that briefly shipped before the product-aligned rename, the legacy aliases `file_transcription`, `in_call_transcription`, and `ai_assistant_transcription` are silently accepted and normalized to `file_based`, `in_call`, and `ai_assistant` respectively. The response always emits the canonical (post-rename) values.
        schema:
          $ref: '#/components/schemas/STTServiceType'
      - name: provider
        in: query
        required: false
        description: Filter to entries for a specific STT provider. The enum mirrors the providers advertised across the speech-to-text spec (including `google` and `telnyx`, which are accepted as WebSocket transcription engines). A provider that has no models currently registered for any service type will return an empty `data` array rather than an error.
        schema:
          type: string
          enum:
          - deepgram
          - speechmatics
          - assemblyai
          - xai
          - soniox
          - parakeet
          - humain
          - reson8
          - cohere
          - azure
          - openai
          - google
          - telnyx
      responses:
        '200':
          description: List of supported STT providers and models.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/STTProvidersResponse'
        '400':
          description: Bad request — invalid filter value.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/speech-to-text_Errors'
              example:
                errors:
                - code: '10015'
                  title: Bad Request
                  detail: The request failed because it was not well-formed.
        '401':
          description: Authentication failed — missing or invalid API key.
        '422':
          $ref: '#/components/responses/speech-to-text_UnprocessableEntityResponse'
      x-latency-category: responsive
components:
  schemas:
    STTProvidersMeta:
      type: object
      properties:
        total:
          type: integer
          description: Total number of entries returned.
          example: 12
      required:
      - total
    speech-to-text_Errors:
      properties:
        errors:
          type: array
          items:
            $ref: '#/components/schemas/speech-to-text_Error'
    speech-to-text_Error:
      required:
      - code
      - title
      properties:
        code:
          type: string
          format: integer
        title:
          type: string
        detail:
          type: string
        source:
          type: object
          properties:
            pointer:
              description: JSON pointer (RFC6901) to the offending entity.
              type: string
              format: json-pointer
            parameter:
              description: Indicates which query parameter caused the error.
              type: string
        meta:
          type: object
    STTServiceType:
      type: string
      description: Service surface a model is available on. `ai_assistant` is the STT surface configured via Call Control voice-assistant transcription; it covers both live-streaming and non-streaming/batch models (matching the `TranscriptionConfig.model` enum on `call-control` voice assistants).
      enum:
      - streaming
      - file_based
      - in_call
      - ai_assistant
    STTProvider:
      type: object
      description: A (provider, model) tuple along with the service surfaces it supports. Each entry in `service_types` describes one surface and the languages accepted on it.
      properties:
        provider:
          type: string
          description: STT provider name.
          example: deepgram
        model:
          type: string
          description: Provider-scoped model name.
          example: deepgram/nova-3
        hosted:
          type: boolean
          description: Whether this model runs on Telnyx-hosted infrastructure (`true`) or is provided by a third-party vendor (`false`).
        service_types:
          type: array
          description: Service surfaces this (provider, model) supports. When the request filters by `service_type`, only the matching nested entry is returned for each matching model.
          items:
            $ref: '#/components/schemas/STTProviderServiceType'
      required:
      - provider
      - model
      - hosted
      - service_types
    STTProviderServiceType:
      type: object
      description: A supported service surface for a given (provider, model), along with the language codes accepted on that surface. Language support can differ per surface — for example, a model may accept a narrower language set for streaming than for file transcription.
      properties:
        type:
          $ref: '#/components/schemas/STTServiceType'
        languages:
          type: array
          description: Languages accepted on this service surface, in the provider's native code format. `auto` indicates the provider performs language detection.
          items:
            type: string
          example:
          - en
          - es
          - fr
      required:
      - type
      - languages
    STTProvidersResponse:
      type: object
      description: List of supported STT providers and models.
      properties:
        data:
          type: array
          items:
            $ref: '#/components/schemas/STTProvider'
        meta:
          $ref: '#/components/schemas/STTProvidersMeta'
      required:
      - data
      - meta
  responses:
    speech-to-text_UnprocessableEntityResponse:
      description: Unprocessable entity. The request was well-formed but could not be processed due to semantic errors. This includes validation errors, invalid parameter values and business logic violations.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/speech-to-text_Errors'
          examples:
            missing_required_parameter:
              summary: Missing required parameter
              value:
                errors:
                - code: '10004'
                  title: Missing required parameter
                  detail: The 'transcription_engine' parameter is required and cannot be blank.
                  source:
                    pointer: /transcription_engine
  securitySchemes:
    BearerAuth:
      type: http
      scheme: bearer
      bearerFormat: API key
      description: 'Telnyx API key supplied as `Authorization: Bearer <token>`. In production, auth may be validated by the API gateway and forwarded via Telnyx auth headers.'
    Payment:
      type: apiKey
      in: header
      name: Authorization
      description: 'Machine Payment Protocol credential used on paid retries, sent as `Authorization: Payment ...`. Obtained by paying a challenge returned in the `WWW-Authenticate` header of a 402 response. This is not a Telnyx API key; initial challenge requests use standard bearer authentication instead.'
    agent-memory_bearerAuth:
      type: http
      scheme: bearer
      description: Telnyx API key
    bearerAuth:
      type: http
      scheme: bearer
    branded-calling_bearerAuth:
      type: http
      scheme: bearer
      description: Telnyx API key. Generate one at https://portal.telnyx.com/#/app/api-keys.
    collections_bearerAuth:
      type: http
      scheme: bearer
      description: Telnyx API key. Collections and results are automatically scoped to the authenticated user's organization.
    number-reputation_bearerAuth:
      type: http
      scheme: bearer
      description: Telnyx API key. Generate one at https://portal.telnyx.com/#/app/api-keys.
    oauthClientAuth:
      type: oauth2
      flows:
        clientCredentials:
          tokenUrl: https://api.telnyx.com/v2/oauth/token
          scopes:
            admin: Administrative access to Telnyx resources
        authorizationCode:
          authorizationUrl: https://api.telnyx.com/v2/oauth/authorize
          tokenUrl: https://api.telnyx.com/v2/oauth/token
          refreshUrl: https://api.telnyx.com/v2/oauth/token
          scopes:
            admin: Administrative access to Telnyx resources
      description: OAuth 2.0 authentication for Telnyx API and MCP integrations
    outbound-voice-profiles_bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: JWT
    pronunciation-dicts_bearerAuth:
      type: http
      scheme: bearer
      description: Telnyx API v2 key. Obtain from https://portal.telnyx.com
    rcs-registration_bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: API key
    stored-payment-transactions_bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: JWT
    transcriptions-search_bearerAuth:
      type: http
      scheme: bearer
      description: Telnyx API key. Results are automatically scoped to the authenticated user's organization.
    web-search_bearerAuth:
      type: http
      scheme: bearer
      description: Telnyx API key
x-service-info:
  categories:
  - communication
  - developer-tools
  docs:
    apiReference: https://developers.telnyx.com
    homepage: https://telnyx.com
    llms: https://telnyx.com/llms.txt