TitleCheckAvailabilityCal node returns 404 due to invalid Cal Retell AI #❓・ai-evy-support

TitleCheckAvailabilityCal node returns 404 due to ...

Salty

12/14/2025, 7:49 PM

@AI Evy Title CheckAvailabilityCal node returns 404 due to invalid Cal.com v2 endpoint Description The built-in CheckAvailabilityCal node is calling an invalid Cal.com v2 endpoint, which results in consistent 404 errors even when all required parameters are correctly provided. This is not caused by date extraction, timezone, or flow logic. The issue is reproducible with valid inputs and appears to be an outdated or incorrect Cal API integration in Retell. Steps to Reproduce Use the CheckAvailabilityCal node with a valid eventTypeId Provide a valid date in YYYY-MM-DD format Ensure timezone is set (e.g. Europe/Copenhagen) Run the flow Actual Result The node sends the following request: GET /v2/event-types/{eventTypeId}/availability?date=YYYY-MM-DD&timezone=Europe/Copenhagen This request returns: 404 Not Found Expected Result Availability should be fetched successfully from Cal.com using the correct v2 endpoint: GET /v2/slots with required query parameters: eventTypeId start end timeZone and required headers: Authorization: Bearer cal-api-version: 2024-09-04 Evidence Flow logs confirm: booking_date is correctly populated (e.g. 2024-06-14) The 404 persists despite valid input Error response explicitly states: Cannot GET /v2/event-types/{eventTypeId}/availability Impact The CheckAvailabilityCal node is currently unusable with Cal.com v2 and prevents any availability-based booking flows from functioning. Conclusion This is an integration bug on Retell’s side. The node appears to rely on a deprecated or non-existent Cal.com endpoint and should be updated to use the correct v2 /slots API.

AI Evy

12/14/2025, 7:49 PM

Thanks for tagging me @Salty. I'll look through relevant sources and get back to you shortly.

AI Evy

12/14/2025, 7:49 PM

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

AI Evy

12/14/2025, 7:49 PM

### Answer --- Thanks for the detailed bug report. Based on the available documentation, I can confirm that Retell AI provides a built-in

check_calendar_availability

function for Cal.com integration. [(1) ]() The documentation describes the setup process (API key, Event Type ID, timezone) , but does not specify the exact Cal.com API endpoint Retell uses internally. There is a Discord discussion noting that Cal.com's v2 API provides outputs in UTC only, and that the v1 endpoint (` was confirmed to work correctly with timezone support. [(2) ]() What you can do: 1. Report this directly to Retell support — Since this appears to be an internal integration issue with how Retell calls Cal.com's API, the Retell team would need to update their backend integration. 2. Workaround option — If you need immediate functionality, you could create a custom function that calls the correct Cal.com v2

/slots

endpoint yourself, rather than relying on the built-in node. [(3) ]() I don't have documentation confirming the specific endpoint Retell uses or any official acknowledgment of this bug. You may want to reach out directly: - Visit [Contact Sales]() - Check [Retell AI GitHub]() Would you like guidance on building a custom Cal.com availability function as a workaround?

AI Evy

12/14/2025, 7:49 PM

To learn more, see the sources I considered: [[1] Check Calendar Availability](https://docs.retellai.com/build/check-availability) [[2] Discord message from @sanava.ai on 2024-11-06](https://discord.com/channels/1186424376300679209/1294891368505937952/1303839533699170424) [[3] API Integration](https://www.retellai.com/glossary/api-integration)

Salty

12/14/2025, 7:51 PM

How do i get incontact with retell support? @User

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