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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 and your assistant keeps working unchanged while gaining response caching. Prerequisites:
  • A Vapi account with an assistant you can edit.
  • An SLNG key from app.slng.ai/api-keys.
  • Your region-specific router base URL from your SLNG contact (looks like https://india.context-router.slng.ai/v1).

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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

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

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:

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Verify it is routing

Check Vapi’s call logs, or replay a turn directly with the cURL example. On a cached turn the router response carries cached: true. If you never see it, confirm caching is enabled for your org.

Context Router

Endpoint, auth, request body, and response caching.

Voice platform integrations

Other ways to route your stack through SLNG.