We have an assistant that does a lookup of the caller (in Hubspot) based on the {{customer.number}}, and personalizes the greeting if one record is found. It is rather straightfoward but has stopped working reliably. These are calls from a US mobile, to a number attached to a Vapi Assistant, which is configured to consume {{customer.number}}, store and normalize it as US 10-digit (no dashes), and apply in a tool for lookup. But it is now most often 1) hallucinating the customer.number or 2) finding it as blank / null. Please advice. See calls: - 019a001c-c5e7-7558-8f8f-01e29830088a - hallucinated a number from the prompt, not from the caller's customer.number - 019a0024-7585-7dd6-bc70-5d1ea9da03ea - had no caller number - 019a0018-d1a7-7668-a85b-5800f94db4b9 - hallucinated the caller number as 5551234567

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To reliably personalize by caller number, switch to server-side personalization by extracting the phone number from the webhook payload and passing it as a variable. Here’s a Node.js/Express example:

js
app.post("/api/assistant-selector", async (req, res) => {
  if (req.body.message?.type === "assistant-request") {
    const phoneNumber = req.body.call.from.phoneNumber;
    const customer = await hubspotAPI.getCustomerByPhone(phoneNumber);
    res.json({
      assistantId: "your-assistant-id",
      assistantOverrides: {
        variableValues: {
          customerName: customer?.name || "valued customer",
          customerPhone: phoneNumber
        }
      }
    });
  }
});

This avoids LLM hallucination and ensures the actual caller number is used for lookups and personalization. Source: - [Personalization with user information](https://docs.vapi.ai/assistants/personalization)

Note: this call a few minutes ago did work as expected. Customer.number populated (from ANI / the number calling in), applied to lookup, found, personalized the greeting. Unfortunately, it's 1 out of 10 or so. - 019a0036-f828-7000-aacb-ff90bf99e6c6

Message marked as helpful by @GIDEON! 🎉

Question -- I'm reading some places that {{customer.phone}} is the right variable, not {{customer.number}}. Is that true?

{{customer.number}} is the correct name for the default variable. If it is not passed in from the customers side then it will be blank and unavailable in the logs