> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.vapi.ai/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.vapi.ai/_mcp/server.

# Model fallback configuration

> Configure fallbackModels in Vapi so a backup language model takes over automatically when your primary LLM fails. Covers which providers currently support model fallback and how it differs from voice and transcriber fallback.

## Overview

Model fallback lets a backup language model take over automatically if your primary model fails, so the call keeps going instead of ending in an error.

> **Note**
>
> Model fallback is currently supported for the [OpenAI](/providers/model/openai) and [Anthropic Bedrock](/providers/model/anthropic-bedrock) providers only. It is not yet a cross-provider fallback like [voice fallback](/voice-fallback-plan) or [transcriber fallback](/customization/transcriber-fallback-plan), which can fall back to a different provider entirely. Without `fallbackModels` configured, your call ends with an error if your chosen model provider fails.

## How it works

When a model failure occurs, Vapi will:

1. Detect the failure of the primary model.
2. If `fallbackModels` is configured, switch to the first fallback model in the list.
3. For OpenAI, continue through the rest of your specified list if subsequent failures occur. For Anthropic Bedrock, only one fallback model can be configured, so Vapi tries that single model.
4. Terminate the call only if every configured fallback has also failed.

Fallback models stay on the same provider as your primary model. To protect against a provider-wide outage, pair model fallback with [voice fallback](/voice-fallback-plan) and [transcriber fallback](/customization/transcriber-fallback-plan) on the other two pipeline components, which do support cross-provider fallback.

## Configure via API

Add `fallbackModels` directly to your assistant's `model` object. There is no separate `fallbackPlan` wrapper for models — unlike `voice.fallbackPlan.voices` and `transcriber.fallbackPlan.transcribers`, `fallbackModels` is a sibling property of `model.model` itself.

### OpenAI

Set `model.fallbackModels` to an ordered list of OpenAI model IDs. Vapi tries them in order if the primary model fails.

```json
{
  "model": {
    "provider": "openai",
    "model": "gpt-5.5",
    "fallbackModels": ["gpt-5.4", "gpt-4.1"]
  }
}
```

> **Note**
>
> You shouldn't need to set this unless you have a specific reason to — Vapi automatically finds the fastest fallback models that make sense for your primary model.

### Anthropic Bedrock

Set `model.fallbackModels` to at most one same-provider Claude model ID available through Bedrock.

```json
{
  "model": {
    "provider": "anthropic-bedrock",
    "model": "claude-sonnet-4-6",
    "fallbackModels": "claude-haiku-4-5-20251001"
  }
}
```

> **Note**
>
> The fallback model is resolved using the call's Bedrock credential region (or `ANTHROPIC_BEDROCK_AWS_REGION`). A fallback name with no inference profile in that region is skipped and a warning is logged — Vapi never silently remaps it to a US or global profile. On Vapi EU, a fallback name without an EU inference profile is rejected at write time. `fallbackModels` cannot be combined with `thinking` in this release.

## Other providers

Vapi's other language model providers — including [Anthropic](/providers/model/anthropic) (non-Bedrock), [Google](/providers/model/gemini), [Groq](/providers/model/groq), [xAI](/providers/model/xai), [Mistral](/providers/model/mistral), [MiniMax](/providers/model/minimax), and [Custom LLM](/customization/custom-llm/fine-tuned-openai-models) — do not currently expose a `fallbackModels` field. If your primary model is on one of these providers and it fails, the call ends with an error unless you handle retries at the application layer.

## FAQ

#### Can I fall back from one provider to a different provider, like voice and transcriber fallback do?

Not yet. `fallbackModels` only lets you specify backup models from the same provider as your primary model. Cross-provider model fallback isn't currently supported — use [voice fallback](/voice-fallback-plan) and [transcriber fallback](/customization/transcriber-fallback-plan) to protect those two pipeline components against a provider-wide outage.

#### Does fallback affect pricing?

You're billed normally for whichever model actually generates the response, whether that's your primary model or a fallback.

#### Why am I not seeing a fallbackModels option for my provider?

`fallbackModels` is currently only available on `OpenAIModel` and `AnthropicBedrockModel`. It isn't exposed for other providers yet.

## Related

#### [Voice fallback configuration](/voice-fallback-plan)

Configure fallback voices that activate automatically when your primary voice provider fails.

#### [Transcriber fallback configuration](/customization/transcriber-fallback-plan)

Configure fallback transcribers so calls keep working if your primary speech-to-text provider fails.

#### [Model providers](/providers/model/overview)

Compare every language model provider Vapi supports.