### Answer Based on the available sources, I don't have specific documentation about fetching live prices from a booking engine during a call. However, the general approach in Retell AI for retrieving external data (like live prices) during a call is to use custom functions. The appointment booking documentation mentions that you can "write a custom function to connect" to external services beyond the native Cal.com integration. [(1) ]() This means you could: 1. Create a custom function that calls your booking engine's API to retrieve live pricing 2. Add that function to your agent's tools 3. Include logic in your prompts to trigger the function and relay the pricing information to the caller Check out these potentially useful sources: - [AI Appointment Scheduling with Voice AI Booking Assistant]() - [Create Retell LLM]() Would you like me to provide a general answer about implementing custom functions for external API calls?

​ To learn more, see the sources I considered: [[1] AI Appointment Scheduling with Voice AI Booking Assistant](https://www.retellai.com/features/book-appointments) ​

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

​ To learn more, see the sources I considered: [[1] Knowledge Base](https://docs.retellai.com/build/knowledge-base) [[2] Using knowledge base not how I wanted](https://discord.com/channels/1186424376300679209/1357009953247727808) ​

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

### Answer ### Answer While the knowledge base does support importing content via URLs, the URL source is designed to import website content from web pages. [(1) ]() A Google Sheet share URL would not work the same way as a standard webpage URL—the knowledge base URL feature is built to crawl and parse web page content, not access data from a Google Sheets document directly. Your best options for pricing data: 1. Export to CSV/XLSX – Download your Google Sheet as a

.csv

or

.xlsx

file and upload it directly to the knowledge base. - Note: CSV/XLSX files have a limit of 1000 rows and 50 columns. 2. Custom function – For live/dynamic pricing that changes frequently, a custom function that calls your Google Sheets API would give you real-time data during calls rather than relying on a static knowledge base upload.

​ To learn more, see the sources I considered: [[1] Knowledge Base](https://docs.retellai.com/build/knowledge-base) ​

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

@AI Evy how can i do the custom function call with google sheets api?

### Answer ### Answer To connect Retell AI with Google Sheets via a custom function, you'll need to set up a webhook endpoint that Retell calls, which then interacts with the Google Sheets API. [(1) ]() High-level steps: 1. Create a custom function in Retell – In your agent's "Functions" section, click "+ Add" and select "Custom Function". 2. Set up your endpoint URL – This is a server you control (or a no-code tool like Make.com or N8N) that receives Retell's request and calls the Google Sheets API. [(1) ]() [(2) ]() 3. Configure the HTTP method – Choose GET, POST, PATCH, PUT, or DELETE depending on whether you're reading or writing data. [(1) ]() 4. Define parameters – Specify what data Retell should send to your endpoint (e.g., customer name, pricing lookup key) . 5. Set up Google Sheets API credentials – In Google Cloud Console, enable the Google Sheets API and create OAuth credentials. Add your email as a test user. [(2) ]() 6. Connect your middleware to Google Sheets – Your endpoint receives Retell's request, queries Google Sheets, and returns the result. Request format Retell sends to your endpoint: [(1) ]() - Header:

X-Retell-Signature

for verification - Body (for POST/PUT/PATCH) : includes

name

,

call

object, and

args

Response requirements: - Status code 200-299 for success - Can return string, JSON object, buffer, or blob (capped at 15,000 characters) Verification example (TypeScript) :

typescript
import { Retell } from "retell-sdk";
this.app.post("/check-weather", async (req: Request, res: Response) => {
  if (
    !Retell.verify(
      JSON.stringify(req.body) ,
      process.env.RETELL_API_KEY,
      req.headers["x-retell-signature"] as string,
    )
  ) {
    console.error("Invalid signature") ;
    return;
  }
  const content = req.body;
  // Your Google Sheets logic here
}) ;

For a step-by-step walkthrough using N8N with Google Sheets, there's a community workshop video: [Personalization with Google Sheets]() [(2) ]()

​ To learn more, see the sources I considered: [[1] Integrate any system with custom function](https://docs.retellai.com/build/single-multi-prompt/custom-function) [[2] Personalization with Google Sheets]() ​

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