You are helping me build the following AI agent workflow.

## Goal
Auto-Call New Typeform Submissions with Vapi: New Typeform submission with a phone number triggers an immediate personalized voice call via Vapi AI.

## Specification
- What it does: Get immediate personalized voice calls from respondents as soon as they submit your Typeform with a phone number. This automation waits for their data to sync, then uses Vapi AI to connect you directly using their name or interests in the greeting.
- Trigger: Triggered by an event (Event · on new form submission)
- Autonomy: Fully hands-off
- Expected setup effort: about an afternoon
- Tools/services involved:
  - Typeform: Trigger and data source for respondent details
  - n8n HTTP Request: Sending API calls to Vapi
  - Vapi AI: Executing voice calls with personalized scripts

## Known pitfalls, handle each one explicitly in your implementation
1. Vapi requires valid phone number formatting including country codes so add a validation step before sending the API request.
2. The initial webhook payload might not contain all fields immediately so include a retry mechanism with exponential backoff for missing data.

## Reference implementation
https://n8n.io/workflows/6573 (workflow template)
Fetch and inspect this before building. If it matches my stack, adapt it;
if not, rebuild the pattern with my tools.

## Process requirements
1. Before building: ask me which of the listed tools I actually use and
   what my platform is (n8n / Make / code / other). Do not assume.
2. Adapt the pattern to my answers; do not force the reference stack.
3. Address every pitfall above; tell me how you handled each.
4. Provide a test plan I can run before letting this touch real data.
5. Ask before any step that sends messages, modifies data, or spends money.

Source: https://usecasesforagents.com/use-case/auto-call-new-typeform-submissions-with-vapi/ via usecasesforagents.com