Personalization with user information

Customer Calls Your Number

When a call comes in, Vapi sends a request to your server instead of using a fixed assistant configuration.

Your Server Looks Up the Caller

Your server receives the request, identifies the caller (for example, by phone number), and fetches relevant customer data from your database or CRM.

Your Server Responds with Assistant Details

Your server responds to Vapi with either:

• An existing assistant ID and a set of dynamic variables to personalize the conversation, or
• A complete assistant configuration, with customer data embedded directly in the prompts or instructions.

Vapi Handles the Call

Vapi uses the personalized assistant configuration or variables to guide the conversation, referencing the customer’s information as needed.

Add Dynamic Variables to Your Assistant

Use variable placeholders in your assistant’s instructions or messages with the {{variable_name}} syntax.

Example:
"Hello {{customerName}}! I see you've been a {{accountType}} customer since {{joinDate}}."

Configure Your Phone Number to Use Your Server

Update your phone number so that Vapi sends incoming call events to your server, rather than using a static assistant.

1
PATCH /phone-number/{id}
2
{
3
  "assistantId": null,
4
  "squadId": null,
5
  "server": {
6
    "url": "https://your-server.com/api/assistant-selector"
7
  }
8
}

Implement Your Server Endpoint

Your server should handle POST requests from Vapi and return either:

Option 1: Use an Existing Assistant with Dynamic Variables

1
app.post("/api/assistant-selector", async (req, res) => {
2
  if (req.body.message?.type === "assistant-request") {
3
    const phoneNumber = req.body.call.from.phoneNumber;
4
    const customer = await crmAPI.getCustomerByPhone(phoneNumber);
5
6
    res.json({
7
      assistantId: "asst_customersupport",
8
      assistantOverrides: {
9
        variableValues: {
10
          customerName: customer.name,
11
          accountType: customer.tier,
12
          joinDate: customer.createdAt
13
        }
14
      }
15
    });
16
  }
17
});

Option 2: Return a Complete Assistant Configuration

1
app.post("/api/assistant-selector", async (req, res) => {
2
  if (req.body.message?.type === "assistant-request") {
3
    const phoneNumber = req.body.call.from.phoneNumber;
4
    const customer = await crmAPI.getCustomerByPhone(phoneNumber);
5
6
    res.json({
7
      assistant: {
8
        name: "Dynamic Customer Support Assistant",
9
        model: {
10
          provider: "openai",
11
          model: "gpt-4o",
12
          messages: [{
13
            role: "system",
14
            content: `You are helping ${customer.name}, a ${customer.tier} member since ${customer.createdAt}.`
15
          }]
16
        },
17
        voice: {
18
          provider: "11labs",
19
          voiceId: "shimmer"
20
        }
21
      }
22
    });
23
  }
24
});