Quick Question: How to access callId in active call? I need to pass the conversation's callId to my api. I can see it in the paylod (attributes.callId), but how do I reference it in my system prompt? Should I use: {{callId}} {{call.id}} {{attributes.callId}} Something else? Is there documentation on available system/conversation variables? Thanks!

Based on the documentation I have found, dynamic variables in Vapi are referenced in prompts using double curly braces, like

{{variableName}}

. However, I do not see

callId

,

call.id

, or

attributes.callId

listed as default variables available for use in system prompts. The documentation provides a list of default variables (such as

{{now}}

,

{{customer.number}}

, etc.) and explains how to use custom variables by passing them via the API, but does not mention a built-in call ID variable for prompts. Could you clarify if you are looking to reference the call ID that is generated by Vapi itself, or a custom call identifier you are passing in your API payload? This will help determine if you need to define a custom variable or if there is a built-in option. For more details on available variables, you can review the [Vapi dynamic variables documentation](https://docs.vapi.ai/assistants/dynamic-variables). Source: - [Vapi Dynamic Variables Documentation](https://docs.vapi.ai/assistants/dynamic-variables)

im looking to reference the call ID that is generated by Vapi itself how to pass with callid in to API

Hi there, For System Prompt Template Variables: The

callId

is not currently available as a default template variable in the system prompt using

{{callId}}

or

{{call.id}}

syntax. The available default variables are

{{now}}

,

{{date}}

,

{{time}}

,

{{customer.number}}

,

{{transport.conversationType}}

, etc. Recommended Approach - Use Tools/Server URL: The most reliable way to access the

callId

is through custom tools or server URL webhooks. When Vapi calls your API endpoint (via a tool or server message), the payload automatically includes the full call object with the `id`:

{
  "message": {
    "call": {
      "id": "call-uuid",
      "orgId": "org-uuid",
      "type": "webCall",
      ...
    }
  }
}

Options for your use case: 1. API Request Tool with LiquidJS - If using the

apiRequest

tool type, you can use LiquidJS syntax in URLs, headers, and body. You may be able to access call context variables this way. 2. Custom Tool/Server Endpoint - Set up your tool's server URL to receive the full payload, extract

message.call.id

, and use it in your business logic. 3. Server URL Webhooks - Configure a server URL on your assistant/phone number to receive call events containing the call ID. Documentation references: • Dynamic variables: [https://docs.vapi.ai/assistants/dynamic-variables](https://docs.vapi.ai/assistants/dynamic-variables) • Custom tools: [https://docs.vapi.ai/tools/custom-tools](https://docs.vapi.ai/tools/custom-tools) • API Request tool: [https://docs.vapi.ai/tools/default-tools](https://docs.vapi.ai/tools/default-tools) Let me know if you need help implementing any of these approaches! Regards Vapi Support