Hi VAPI Team, I have an issue where {{variable}} placeholders in my system prompt are not being replaced during phone calls. Configuration: - Assistant ID: 72577c85-81d4-47b4-99b5-0ca8b6ed7a63 - Model: gpt-4o-mini (OpenAI) - System prompt contains: {{user_name}}, {{conversation_count}}, {{last_topics}}, {{conversation_summary}} - Webhook URL: https://ocixoxjozzldqldadrip.supabase.co/functions/v1/vapi-webhook - firstMessageMode: assistant-speaks-first-with-model-generated-message Webhook Works Correctly: I tested my webhook directly - it correctly returns: { "assistantId": "72577c85-81d4-47b4-99b5-0ca8b6ed7a63", "assistantOverrides": { "variableValues": { "user_name": "Robert", "conversation_count": "5", "last_topics": "Palenie, Stres, Praca", "conversation_summary": "User discussed quitting smoking..." } } } Problem: When I check recent call logs (e.g. call ID 019a26b4-974e-7bbb-81c0-4f248d1f9a34), the system message shows: - {{user_name}} - NOT replaced (literal text sent to GPT) - {{conversation_count}} - NOT replaced - No webhook logs in call artifact - AI responds as if variables are still placeholders Questions: 1. Does assistant-request webhook get called for inbound phone calls? 2. Are {{variables}} supposed to work with OpenAI models or only Claude? 3. Is there a configuration I'm missing to enable variable replacement? 4. How can I debug this - are there webhook logs I can check? Expected: AI says "Cześć Robert! To nasza 5. rozmowa..." (Hello Robert! This is our 5th conversation) Actual: AI says generic greeting, doesn't use memory Please help! Thank you!

To enable variable replacement in your system prompt, update your phone number configuration to use your webhook instead of a static assistant. Use this PATCH request (replace

{id}

with your phone number's ID):

json
PATCH /phone-number/{id}
{
  "assistantId": null,
  "squadId": null,
  "server": {
    "url": "https://ocixoxjozzldqldadrip.supabase.co/functions/v1/vapi-webhook"
  }
}

After this change, Vapi will call your webhook for inbound calls and replace

{{variables}}

as expected. [See full details in the documentation.](https://docs.vapi.ai/assistants/personalization#configure-your-phone-number-to-use-your-server) Source: - [Personalization with user information](https://docs.vapi.ai/assistants/personalization)