# AI stops answering in Voice Chat and when I use Text Chat it starts an error called Failed to get LLM response Error: Error encountered in LLM call

**URL:** <https://community.retellai.com/t/ai-stops-answering-in-voice-chat-and-when-i-use-text-chat-it-starts-an-error-called-failed-to-get-llm-response-error-error-encountered-in-llm-call/924>\
**Category:** Support Help\
**Tags:** bug\
**Created:** [February 23, 2026, 12:58pm UTC](https://community.retellai.com/t/ai-stops-answering-in-voice-chat-and-when-i-use-text-chat-it-starts-an-error-called-failed-to-get-llm-response-error-error-encountered-in-llm-call/924 "2026-02-23T12:58:36Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![paumalfi](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/paumalfi/32/874_2.png) [@paumalfi](https://community.retellai.com/u/paumalfi)\
**Post date:** [February 23, 2026, 12:58pm UTC](https://community.retellai.com/t/ai-stops-answering-in-voice-chat-and-when-i-use-text-chat-it-starts-an-error-called-failed-to-get-llm-response-error-error-encountered-in-llm-call/924/1 "2026-02-23T12:58:36Z")

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**Failed to get LLM response**

Error: Error encountered in LLM call

each time I try to use the Voice Chat it stays silent. I have found that the error is in the function of book\_appointment\_cal. Because when i delete that function, it works perfectly fine.

I need help cuz without this i cant really do much with the Ai assistant. Here you have 2 photos, 1 with the problem on Voice Chat (no response) and another one with the Text Chat

(I can only put 1 photo but in the voice chat it literally says nothing)

 ![Captura de pantalla 2026-02-23 120223](https://canada1.discourse-cdn.com/flex008/uploads/retell1/original/1X/09bbdd800b1af0b2fc7ed065b322ea486cd92b33.png)

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**Author:** ![support2](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/support2/32/15_2.png) [@support2](https://community.retellai.com/u/support2)\
**Post date:** [February 23, 2026, 12:59pm UTC](https://community.retellai.com/t/ai-stops-answering-in-voice-chat-and-when-i-use-text-chat-it-starts-an-error-called-failed-to-get-llm-response-error-error-encountered-in-llm-call/924/2 "2026-02-23T12:59:01Z")

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The “error validating [cal.com](http://cal.com) tools” message when using the `book_appointment_cal` function typically stems from credential issues[(1)](https://community.retellai.com/t/error-when-using-booking-functions/337).

**Required Configuration**

The `book_appointment_cal` tool requires these specific fields[(2)](https://docs.retellai.com/api-references/get-retell-llm)[(3)](https://docs.retellai.com/api-references/create-retell-llm)[(4)](https://docs.retellai.com/api-references/update-retell-llm)[(5)](https://docs.retellai.com/api-references/list-retell-llms):

```json
{
  "type": "book_appointment_cal",
  "name": "book_appointment",
  "description": "Book an annual check up.",
  "cal_api_key": "cal_live_xxxxxxxxxxxx",
  "event_type_id": 60444,
  "timezone": "America/Los_Angeles"
}

```

[(2)](https://docs.retellai.com/api-references/get-retell-llm), [(3)](https://docs.retellai.com/api-references/create-retell-llm), [(4)](https://docs.retellai.com/api-references/update-retell-llm), [(5)](https://docs.retellai.com/api-references/list-retell-llms)

**Common Issues to Check**

1. **Event Type ID Format** - Must be a number only (e.g., `60444`), not a URL or string with slashes[(1)](https://community.retellai.com/t/error-when-using-booking-functions/337)

2. **API Key Format** - Should start with `cal_live_` for production keys[(2)](https://docs.retellai.com/api-references/get-retell-llm)[(3)](https://docs.retellai.com/api-references/create-retell-llm)[(4)](https://docs.retellai.com/api-references/update-retell-llm)[(5)](https://docs.retellai.com/api-references/list-retell-llms)

3. **API Key Validity** - Try regenerating your API key in [Cal.com](http://Cal.com) settings[(1)](https://community.retellai.com/t/error-when-using-booking-functions/337)

4. **API Key Permissions** - Verify the key has proper permissions in [Cal.com](http://Cal.com)[(1)](https://community.retellai.com/t/error-when-using-booking-functions/337)

**How to Get Credentials**

- Navigate to Settings → Developer → API Keys in your [Cal.com](http://Cal.com) dashboard[(1)](https://community.retellai.com/t/error-when-using-booking-functions/337)
- The Event Type ID is the number in the URL when you open your event type (e.g., in `https://app.cal.com/your-username/event-type/1427703`, the ID is `1427703`)[(1)](https://community.retellai.com/t/error-when-using-booking-functions/337)

**Troubleshooting Steps**

- Create a new API key in [Cal.com](http://Cal.com)[(1)](https://community.retellai.com/t/error-when-using-booking-functions/337)
- Test the API key directly with [Cal.com](http://Cal.com)’s API outside of Retell to confirm it works[(1)](https://community.retellai.com/t/error-when-using-booking-functions/337)
- Double-check that the Event Type ID matches exactly what’s in your [Cal.com](http://Cal.com) URL[(1)](https://community.retellai.com/t/error-when-using-booking-functions/337)
- Ensure you’re copying the complete API key without extra spaces[(1)](https://community.retellai.com/t/error-when-using-booking-functions/337)

The timezone parameter is optional but recommended[(1)](https://community.retellai.com/t/error-when-using-booking-functions/337).

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<div class="post-metadata">

**Author:** ![paumalfi](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/paumalfi/32/874_2.png) [@paumalfi](https://community.retellai.com/u/paumalfi)\
**Post date:** [February 23, 2026, 1:43pm UTC](https://community.retellai.com/t/ai-stops-answering-in-voice-chat-and-when-i-use-text-chat-it-starts-an-error-called-failed-to-get-llm-response-error-error-encountered-in-llm-call/924/3 "2026-02-23T13:43:43Z")

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i have everything u said but its not working

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<div class="post-metadata">

**Author:** ![Omar\_Ashraf](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/omar_ashraf/32/102_2.png) [@Omar\_Ashraf](https://community.retellai.com/u/Omar_Ashraf)\
**Post date:** [February 23, 2026, 8:08pm UTC](https://community.retellai.com/t/ai-stops-answering-in-voice-chat-and-when-i-use-text-chat-it-starts-an-error-called-failed-to-get-llm-response-error-error-encountered-in-llm-call/924/4 "2026-02-23T20:08:55Z")

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Hello @paumalfi

Can you share the agent ID?

and step by step how to reproduce it