> ## Documentation Index > Fetch the complete documentation index at: https://docs.topcalls.ai/llms.txt > Use this file to discover all available pages before exploring further. # List available models > Returns all available AI models grouped by mode. **Realtime mode**: Speech-to-speech models for ultra-low latency conversations. **Legacy mode**: Separate STT, LLM, and TTS models that can be mixed and matched. Use this endpoint to discover which models are available and their capabilities. ## OpenAPI ````yaml /api-reference/openapi.json get /v1/models openapi: 3.0.3 info: title: TopCalls Voice API description: > TopCalls Voice Gateway API for creating and managing AI-powered phone calls. ## Authentication All API requests require authentication. Include your API key in the `Authorization` header: ``` Authorization: Bearer tc_live_xxxxx ``` ## Rate Limits Direct call creation via `POST /v1/calls` is limited to your account's `max_calls_per_minute` setting (default: 20) per minute. Exceeding it returns `429 Too Many Requests` with a `Retry-After` header. All endpoints are additionally subject to a flat limit of 120 requests per minute per account (all methods). On a `429`, wait for the number of seconds in the `Retry-After` header, then retry the same request. For automated clients, back off progressively on repeated `429`s. Limits are per account and are shared by all API keys. ## Error Format All errors follow RFC 7807 Problem+JSON format: ```json { "type": "https://api.topcalls.ai/errors/insufficient_quota", "title": "Insufficient Quota", "status": 402, "detail": "You need 5 minutes but have 3.5 remaining" } ``` version: 1.0.0 contact: name: TopCalls Support url: https://topcalls.ai license: name: Proprietary servers: - url: https://api.topcalls.ai description: Production security: [] tags: - name: Calls description: Create and manage phone calls - name: Phone Numbers description: Manage phone numbers and carriers - name: Account description: Account information and usage - name: Webhooks description: Webhook configuration and events - name: Configuration description: Available AI models, voices, and platform capabilities paths: /v1/models: get: tags: - Configuration summary: List available models description: > Returns all available AI models grouped by mode. **Realtime mode**: Speech-to-speech models for ultra-low latency conversations. **Legacy mode**: Separate STT, LLM, and TTS models that can be mixed and matched. Use this endpoint to discover which models are available and their capabilities. operationId: listModels responses: '200': description: Available models grouped by mode content: application/json: schema: type: object properties: realtime: type: array description: Speech-to-speech models for Realtime mode items: type: object properties: id: type: string description: Model identifier to use in API calls displayName: type: string description: Human-readable model name provider: type: string description: Model provider identifier type: type: string description: Model type (sts = speech-to-speech) description: type: string latency: type: string description: Expected latency category supports_tools: type: boolean description: Whether the model supports function calling supports_interruptions: type: boolean description: Whether the model supports barge-in legacy: type: object description: Models for Legacy mode (STT → LLM → TTS pipeline) properties: llm: type: array description: Available LLM models items: type: object properties: id: type: string displayName: type: string provider: type: string description: type: string latency: type: string default: type: boolean description: >- Whether this is the default model for Legacy mode stt: type: array description: Available Speech-to-Text models items: type: object properties: id: type: string displayName: type: string provider: type: string description: type: string languages: type: integer description: Number of supported languages supports_multilingual: type: boolean supports_vocabulary: type: boolean description: Whether the STT model supports custom vocabulary supported_languages: type: array description: Supported languages (code + display name) items: type: object required: - code - displayName properties: code: type: string description: >- Language code (e.g., 'en', 'en-US', 'multi') displayName: type: string description: Human-readable language name stt_settings: type: object description: > Provider-keyed map of tunable STT knob metadata. Each knob carries full slider metadata so the frontend can render a generic slider without provider-specific code. Knob keys vary per provider (e.g. `endpoint_sensitivity`, `interrupt_sensitivity`, `max_delay`). additionalProperties: type: object required: - min - max - default - step - decimals properties: min: type: number description: Slider minimum max: type: number description: Slider maximum default: type: number description: Default value step: type: number description: Slider increment decimals: type: integer description: Display precision unit: type: string description: >- Optional unit suffix (e.g., 's' for seconds) label: type: string description: Short English fallback label description: type: string description: English fallback help text default: type: boolean tts: type: array description: Available Text-to-Speech models items: type: object properties: id: type: string displayName: type: string provider: type: string description: type: string latency: type: string supports_cloning: type: boolean supported_languages: type: array description: Supported languages (code + display name) items: type: object required: - code - displayName properties: code: type: string displayName: type: string default: type: boolean '401': $ref: '#/components/responses/Unauthorized' security: - bearerAuth: [] components: responses: Unauthorized: description: Unauthorized (missing or invalid API key) content: application/problem+json: schema: $ref: '#/components/schemas/Problem' example: status: 401 title: Unauthorized detail: Invalid or missing API key schemas: Problem: type: object required: - status - title properties: type: type: string format: uri description: Error type URI title: type: string description: Error title status: type: integer description: HTTP status code detail: type: string description: Human-readable error detail code: type: string description: > Machine-readable error code for programmatic handling. Present on errors that carry a stable identifier (e.g. `PROMPT_SAFETY_FRAUD`, `job_not_found`, `too_many_ids`, `no_matches`). Distinct from the per-field `errors[].code` used for validation failures. Scenario- specific — see each endpoint's response examples for the exact value. instance: type: string format: uuid description: Request instance ID errors: type: array description: Validation errors (for 400 responses) items: type: object properties: path: type: string description: Field path (e.g., "phone_number", "metadata.from_number") message: type: string description: Error message code: type: string description: Error code (e.g., "invalid_string", "custom") details: type: string description: Additional error details (for provider errors) securitySchemes: bearerAuth: type: http scheme: bearer description: | Use `Authorization: Bearer tc_live_xxxxx` ````