SMS send with dynamic_viarables

Support Help
1

On my Agent Level Webhook URL, I see event: call_analyzed but collected_dynamic_variables, dynamic_variables, and retell_llm_dynamic_variables are all undefined in the payload, even though the call analysis screen shows sms_number under collected variables.
Is there a setting I’m missing to include collected_dynamic_variables in the call_analyzed webhook payload for flow agents, or is this not supported yet?

2

Based on the webhook documentation, the call_analyzed event should include collected_dynamic_variables, retell_llm_dynamic_variables, and metadata fields in the call object payload when they are present(1).

The webhook specification states that if metadata and retell_llm_dynamic_variables are not provided, they will be omitted from the webhook event payload(1). However, collected_dynamic_variables should be included when available, as shown in the call object structure(2)(3)(4).

The call object in webhook payloads includes these fields(2)(3):

  • metadata: An arbitrary object for storage purposes
  • retell_llm_dynamic_variables: Dynamic variables injected into your Response Engine
  • collected_dynamic_variables: Variables collected during the call

Since you’re seeing sms_number in the call analysis screen under collected variables but not receiving it in the webhook payload, this appears to be an unexpected behavior. The documentation shows that collected_dynamic_variables should be part of the call object returned in webhook events(2)(3)(4).

I recommend checking:

  1. Whether your webhook is registered at the agent level correctly(1)
  2. That your endpoint is receiving the complete payload (check raw request body)
  3. Verify the webhook is responding with a 2xx status within 10 seconds(1)

If the issue persists after verification, you may want to contact support:

3

Thanks for the pointers. I’ve verified the agent‑level webhook is set correctly and my endpoint is returning 200 quickly. I can see event: call_analyzed hitting my URL, but in the body, collected_dynamic_variables, dynamic_variables, and retell_llm_dynamic_variables are all undefined for every event.

At the same time, the call analysis page in the dashboard shows sms_number under collected variables. Based on the docs, I’d expect call.collected_dynamic_variables.sms_number to be present in the call_analyzed webhook payload, but it’s not there at all—those properties are missing rather than empty objects.
Is this a known issue with flow agents using Extract Dynamic Variables, or is there a different field/path where you’re currently returning sms_number in the webhook payload?

4

Hello @chris.garlitz

Can you share the call id for this call and a screenshot of the webhook you got.

5

I can help you understand how to retrieve call information and webhook data in Retell AI.

To find your call ID, you can retrieve it from several places:

From Webhook Payloads

When you receive a webhook event, the call ID is included in the payload under the call object(1). The webhook payload structure looks like this:

{
 "event": "call_ended",
 "call": {
 "call_id": "Jabr9TXYYJHfvl6Syypi88rdAHYHmcq6",
 "agent_id": "oBeDLoLOeuAbiuaMFXRtDOLriTJ5tSxD",
 "call_status": "registered"
 }
}

(1)

From API Responses

When you create an outbound phone call, the call ID is returned in the response(2):

{
 "call_id": "Jabr9TXYYJHfvl6Syypi88rdAHYHmcq6",
 "agent_id": "oBeDLoLOeuAbiuaMFXRtDOLriTJ5tSxD"
}

(2)

Similarly, when creating a web call, the call ID is included in the response(3):

{
 "call_id": "Jabr9TXYYJHfvl6Syypi88rdAHYHmcq6",
 "access_token": "eyJhbGciOiJIUzI1NiJ9.eyJ2aWRlbyI6eyJyb29tSm9p"
}

(3)

Webhook Event Types

Retell AI supports three webhook events that will contain the call ID(1):

  • call_started: Triggered when a new call begins(1)
  • call_ended: Triggered when a call completes, transfers, or encounters an error(1)
  • call_analyzed: Triggered when call analysis is complete(1)

If you need to capture webhook data for debugging, you can set up an endpoint following the setup guide(4) and log the incoming requests to review the payload structure and call IDs.