### Answer --- When passing data to a Retell voice agent via Zapier, you'll want to use

retell_llm_dynamic_variables

rather than just

metadata

. [(1) ]() Key distinction: -

metadata

is for storage purposes only and is not used for processing by the agent. -

retell_llm_dynamic_variables

injects key-value pairs directly into your Response Engine prompt and tool descriptions, making them available for the agent to speak. Example:

javascript
retell_llm_dynamic_variables: {
  "customer_name": "John Doe"
}

, [(2) ]() To fix your issue: 1. In your Zapier action that triggers the outbound call, ensure you're mapping your lead data to

retell_llm_dynamic_variables

(not

metadata

) . 2. In your agent's prompt, reference these variables using the format

{{customer_name}}

(or whatever keys you define) . [(1) ]() If you're still having trouble connecting Zapier to Retell, note that you'll need to call the Retell API's Create Phone Call method directly, as there may not be a native Zapier integration. [(3) ]() Check out the [Zapier integration guide]() for more details. [(4) ]()

​ To learn more, see the sources I considered: [[1] Get Call](https://docs.retellai.com/api-references/get-call) [[2] How can I create an outbound call](https://retell.discourse.group/t/how-can-i-create-an-outbound-call/132) [[3] Discord message from @fyodor2572 on 2025-02-16](https://discord.com/channels/1186424376300679209/1294891368505937952/1340548970849636445) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.

### Answer I'm a text-based AI assistant, so I can't view or process images directly. However, if you're troubleshooting your Zapier + Retell integration issue, sharing the following as text or screenshots in this channel could help others assist you: 1. Your Zapier action configuration – specifically the fields you're mapping (check if you're using

retell_llm_dynamic_variables

vs

metadata

) 2. Your agent's prompt – to verify you're referencing variables correctly with

{{variable_name}}

syntax 3. The API request/response – if you can capture the payload being sent to Retell's Create Phone Call endpoint You can paste code snippets or describe what you're seeing, and I'll do my best to help troubleshoot based on Retell AI documentation.

message has been deleted

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.

### Answer Not exactly. There's an important distinction: When you set

retell_llm_dynamic_variables

at call creation time (via the Create Phone Call API) , those variables are injected into your agent's prompt and tool descriptions for that call. [(1) ]() , [(2) ]() However, the Update Call API (

PATCH /v2/update-call/{call_id}

) only allows you to update

metadata

and

data_storage_setting

— not

retell_llm_dynamic_variables

. [(3) ]()

javascript
const callResponse = await client.call.update('call_a4441234567890777c4a4a123e6', {
  data_storage_setting: 'everything_except_pii',
  metadata: { customer_id: 'cust_123', notes: 'Follow-up required' },
}) ;

What this means for your use case: - You cannot push new dynamic variables mid-call to change what the agent says in real-time via the Update Call API - Dynamic variables must be passed when initiating the call through

retell_llm_dynamic_variables

in your Zapier action that triggers the outbound call [(1) ]() , [(4) ]() If you need the agent to have accurate, personalized information, ensure all relevant data is included in

retell_llm_dynamic_variables

at the moment you create the call — not after it starts.

​ To learn more, see the sources I considered: [[1] Dynamic Variables](https://docs.retellai.com/build/dynamic-variables) [[2] Create Web Call](https://docs.retellai.com/api-references/create-web-call) [[3] Update Call](https://docs.retellai.com/api-references/update-call) [[4] How can I create an outbound call](https://retell.discourse.group/t/how-can-i-create-an-outbound-call/132) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.

### Answer Correct. Based on the available documentation: *Webhooks are one-way (Retell → your system) *, not the other way around. The webhook events (

call_started

,

call_ended

,

call_analyzed

) push data from Retell to your endpoint — they don't accept incoming data to update the call. [(1) ]() As mentioned in my previous response, the Update Call API only allows updating

metadata

and

data_storage_setting

— not

retell_llm_dynamic_variables

. And

metadata

is for storage purposes only, not processed by the agent. Summary: - You cannot inject new dynamic variables into an active call mid-conversation - All personalized data the agent needs to speak must be passed via

retell_llm_dynamic_variables

at call creation time - Webhooks flow outbound from Retell to notify your systems of events — they don't accept real-time updates back If your use case requires the agent to access information that changes during the call, you'd need to explore using custom tools/function calling where the agent queries your backend for fresh data when needed.

​ To learn more, see the sources I considered: [[1] Webhook Overview](https://docs.retellai.com/features/webhook-overview) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.