> ## Documentation Index
> Fetch the complete documentation index at: https://dialnexa.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# List Speech-to-Speech Voices

> List voices for speech-to-speech agents.

<span data-api-safety-label="read-only"><Badge color="gray" size="sm" shape="pill">Read only</Badge></span>

<Info>
  **Recommended.** This endpoint is part of the public `/v1` API reference and is the supported path for new integrations. See the [migration guide](/docs/api-reference/v1/migrating-to-v1) for versioning guidance.
</Info>

Returns Speech to Speech voices with the languages and realtime LLM paths each voice supports. Use this endpoint when building a Speech to Speech voice selector or validating an agent configuration before saving it.

## When to use this

* **Building S2S agents**: agents with `pipeline_type: "Speech_To_Speech"` can only use voices from this list, not the general [List Voices](/docs/api-reference/v1/voices/list) catalog.
* **Voice selectors**: populate the voice dropdown in your own tooling when the operator has chosen the Speech to Speech pipeline.
* **Pre-save validation**: confirm the voice, language, and realtime LLM combination is supported before creating or publishing the agent.

The response wraps the records in a `voices` array and returns the full list without pagination metadata.

## Related endpoints

* [Speech To Speech Agents](/docs/agents/speech-to-speech-agents): configure realtime agents.
* [List Voices](/docs/api-reference/v1/voices/list): list cascaded TTS voices.
* [List Voice Languages](/docs/api-reference/v1/voices/languages): inspect language choices for one voice.


## OpenAPI

````yaml GET /v1/voices/s2s
openapi: 3.0.0
info:
  title: DialNexa API
  description: >-
    Public REST API for the DialNexa voice AI platform. Versioned endpoints are
    under /v1; unversioned endpoints are legacy and deprecated.
  version: 1.0.0
servers:
  - url: https://api.dialnexa.com
    description: DialNexa production API
security:
  - bearer: []
tags:
  - name: API Keys
  - name: Agent Functions
  - name: Agents V1
  - name: Agents2
  - name: Batch Calls
  - name: Batch Calls V1
  - name: Call Logs
  - name: Calls
  - name: Calls V1
  - name: Campaign Leads
  - name: Campaigns
  - name: External Webhooks
  - name: Knowledge Base
  - name: Knowledge Base V1
  - name: LLMs
  - name: LLMs V1
  - name: Languages
  - name: Languages V1
  - name: Organization Phone Numbers
  - name: Organization Phone Numbers V1
  - name: Phone Number Pricing
  - name: Phone Number Pricing V1
  - name: Transcribers
  - name: Transcribers V1
  - name: User Webhooks
  - name: User Webhooks V1
  - name: V1
  - name: Voices
  - name: Voices V1
  - name: Webcall
  - name: Workflow Leads
  - name: Workflow Leads V1
  - name: Workflows
  - name: Workflows V1
paths:
  /v1/voices/s2s:
    get:
      tags:
        - Voices
        - Voices V1
        - V1
      summary: List Speech To Speech Voices
      description: >-
        Returns voices that support speech-to-speech mode, along with their
        compatible languages and LLMs.
      operationId: VoicesV1Controller_findAllS2SVoices
      parameters: []
      responses:
        '200':
          description: Speech to speech voices returned successfully.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/S2SVoicesResponseDto'
              examples:
                success:
                  summary: Successful response
                  value:
                    voices:
                      - id: voice_s2s_abc123
                        name: Realtime Voice
                        provider: openai
                        type: speech_to_speech
                        provider_voice_id: ash
                        gender: neutral
                        accent: null
                        icon: null
                        recording: null
                        languages: []
                        llms: []
        '401':
          description: Unauthorized.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              examples:
                error:
                  summary: 401 Unauthorized
                  value:
                    statusCode: 401
                    message: API key is missing or invalid
                    error: Unauthorized
        '403':
          description: Forbidden - API key does not have access to this organization.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              examples:
                error:
                  summary: 403 Forbidden
                  value:
                    statusCode: 403
                    message: You do not have permission to access this resource
                    error: Forbidden
        '500':
          description: Internal server error.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              examples:
                error:
                  summary: 500 Internal Server Error
                  value:
                    statusCode: 500
                    message: Internal server error
                    error: Internal Server Error
      security:
        - bearer: []
components:
  schemas:
    S2SVoicesResponseDto:
      type: object
      properties:
        voices:
          type: array
          items:
            $ref: '#/components/schemas/S2SVoiceDto'
      required:
        - voices
    ErrorResponse:
      type: object
      properties:
        statusCode:
          type: integer
          example: 400
        message:
          oneOf:
            - type: string
            - type: array
              items:
                type: string
          example: phone_number must be a valid E.164 phone number
        error:
          type: string
          example: Bad Request
      required:
        - statusCode
        - message
        - error
    S2SVoiceDto:
      type: object
      properties:
        id:
          type: string
          example: voice_abc123456789
        name:
          type: string
          example: Ash
        provider:
          type: string
          example: openai
          nullable: true
        provider_voice_id:
          type: string
          example: ash
          nullable: true
        gender:
          type: string
          example: male
        accent:
          type: string
          example: american
          nullable: true
        icon:
          type: string
          nullable: true
        recording:
          type: string
          nullable: true
        languages:
          type: array
          items:
            $ref: '#/components/schemas/S2SLanguageSummaryDto'
        llms:
          type: array
          items:
            $ref: '#/components/schemas/S2SLlmSummaryDto'
      required:
        - id
        - name
        - provider
        - provider_voice_id
        - gender
        - accent
        - icon
        - recording
        - languages
        - llms
    S2SLanguageSummaryDto:
      type: object
      properties:
        id:
          type: string
          example: mj17k2hwviopty
        name:
          type: string
          example: Hindi
        code:
          type: string
          example: hi
      required:
        - id
        - name
        - code
    S2SLlmSummaryDto:
      type: object
      properties:
        id:
          type: string
          example: llm_abc123456789
        name:
          type: string
          example: GPT Realtime 2
        provider:
          type: string
          example: openai
        provider_id:
          type: string
          example: gpt-realtime-2
      required:
        - id
        - name
        - provider
        - provider_id
  securitySchemes:
    bearer:
      scheme: bearer
      bearerFormat: JWT
      type: http

````