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

# Connect Vapi to the Context Router

> Point a Vapi assistant at SLNG's OpenAI-compatible Context Router as a custom model to add response caching with a base-URL swap.

Vapi lets you bring your own OpenAI-compatible model by setting a custom provider URL on the assistant's model config. Point that URL at the SLNG [Context Router](https://slng.mintlify.site/context-router.md) and your assistant keeps working unchanged while gaining response caching.

**Prerequisites:**

* A [Vapi](https://vapi.ai) account with an assistant you can edit.
* An SLNG key from [app.slng.ai/api-keys](https://app.slng.ai/api-keys).
* Your region-specific router base URL from your SLNG contact (looks like `https://india.context-router.slng.ai/v1`).

## Placeholders

The snippets below use these placeholders. Replace them before saving.

| Placeholder | Replace with |
| - | - |
| `SLNG_API_KEY` | An SLNG key from [app.slng.ai/api-keys](https://app.slng.ai/api-keys) |
| `https://india.context-router.slng.ai/v1` | The exact region-specific base URL SLNG gave you |

## Dashboard setup

**1. Open your assistant's Model settings**

In the Vapi dashboard, open the assistant you want to route, then go to the **Model** tab.

![Screenshot 2026 07 29 At 10 32 21](https://mintcdn.com/slng/SmJQakEUJwFNsCYg/images/Screenshot-2026-07-29-at-10.32.21.png?fit=max\&auto=format\&n=SmJQakEUJwFNsCYg\&q=85\&s=7ce7fb85de85d5f17b01c356fbb9b866)

Vapi assistant Model tab

**2. Select a custom OpenAI-compatible model**

Choose the **Custom LLM** option (OpenAI-compatible). Set:

* **URL / Base URL:** `https://india.context-router.slng.ai/v1`
* **Model:** `slng/auto`
* **API key:** `SLNG_API_KEY`

![Screenshot 2026 07 29 At 10 31 54](https://mintcdn.com/slng/SmJQakEUJwFNsCYg/images/Screenshot-2026-07-29-at-10.31.54.png?fit=max\&auto=format\&n=SmJQakEUJwFNsCYg\&q=85\&s=565e9d30a2828863d011e70ea2774ed0)

Custom model configuration

**3. Save and place a test call**

Save the assistant and start a call. SLNG now answers every turn.

The equivalent assistant JSON, if you configure Vapi through its API:

```json theme={null}
{
  "model": {
    "provider": "openai",
    "model": "slng/auto",
    "url": "https://india.context-router.slng.ai/v1",
    "apiKey": "SLNG_API_KEY"
  }
}
```

## Verify it is routing

Check Vapi's call logs, or replay a turn directly with the [cURL example](https://slng.mintlify.site/llm-router#making-a-request). On a cached turn the router response carries `cached: true`. If you never see it, confirm caching is enabled for your org.

## Related

> **[Context Router](https://slng.mintlify.site/llm-router)**
>
> Endpoint, auth, request body, and response caching.

> **[Voice platform integrations](https://slng.mintlify.site/integrations/overview.md)**
>
> Other ways to route your stack through SLNG.


This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.