---
title: "Quickstart (API)"
description: "Answer your first phone call with an AI agent: get an API key, create an agent, provision a phone number, and place a live test call — all through the REST API."
---
This guide walks you through the four REST calls it takes to answer
your first phone call with an AI agent.
You'll need a [ThunderPhone account](https://app.thunderphone.com).
Sign up is free and takes under a minute. Prefer clicking to curling?
The [dashboard quickstart](/quickstart-dashboard) reaches the same
first call without writing any code.
## Step 1: Get an API key
Open [app.thunderphone.com](https://app.thunderphone.com).
Go to **Organization → Keys** in the dashboard.
Click **Create key**, give it a name, and copy the
`sk_live_...` value. The raw key is shown **only once** — store it
in your secret manager immediately.
Stuck? [Create a server API key](/guides/api-keys) walks
this flow in step-by-step detail, and the in-app copilot can
spotlight each control for you live.
Throughout this guide, swap `sk_live_YOUR_API_KEY` with the value you
just copied. The key identifies your organization automatically, so
you never need to put an org id in URLs.
## Step 2: Create an agent
An agent defines how the AI handles conversations — prompt, voice,
product tier, tools, and widget eligibility.
```bash cURL
curl -X POST https://api.thunderphone.com/v1/agents \
-H "Authorization: Bearer sk_live_YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"name": "Customer Support",
"prompt": "You are a friendly support agent for Acme Corp. Help with orders, returns, and product info. Be concise and helpful.",
"voice": "john",
"product": "spark"
}'
```
```python Python
import os, requests
agent = requests.post(
"https://api.thunderphone.com/v1/agents",
headers={"Authorization": f"Bearer {os.environ['THUNDERPHONE_API_KEY']}"},
json={
"name": "Customer Support",
"prompt": "You are a friendly support agent for Acme Corp. Help with orders, returns, and product info. Be concise and helpful.",
"voice": "john",
"product": "spark",
},
).json()
print("Agent id:", agent["id"])
```
```javascript Node.js
const agent = await fetch("https://api.thunderphone.com/v1/agents", {
method: "POST",
headers: {
Authorization: `Bearer ${process.env.THUNDERPHONE_API_KEY}`,
"Content-Type": "application/json",
},
body: JSON.stringify({
name: "Customer Support",
prompt: "You are a friendly support agent for Acme Corp. Help with orders, returns, and product info. Be concise and helpful.",
voice: "john",
product: "spark",
}),
}).then((r) => r.json());
console.log("Agent id:", agent.id);
```
Product tiers: `spark` is optimized for cost, `bolt` for speed, and
`storm-base` / `storm-extra` for intelligence on complex prompts. See
[Agents](/api-reference/agents#product-tiers-at-a-glance) for the full
comparison.
## Step 3: Provision a phone number
This call asks ThunderPhone for a number and assigns your
new agent as the inbound handler. (To bring your own number from a VoIP
provider, see [VoIP connections](/api-reference/voip-connections)
instead.)
```bash cURL
# First provision
curl -X POST https://api.thunderphone.com/v1/phone-numbers \
-H "Authorization: Bearer sk_live_YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{"area_code": "415"}'
# Then assign the agent you created in Step 2
curl -X PATCH https://api.thunderphone.com/v1/phone-numbers/ \
-H "Authorization: Bearer sk_live_YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{"inbound_agent_id": 12}'
```
```python Python
number = requests.post(
"https://api.thunderphone.com/v1/phone-numbers",
headers={"Authorization": f"Bearer {os.environ['THUNDERPHONE_API_KEY']}"},
json={"area_code": "415"},
).json()
requests.patch(
f"https://api.thunderphone.com/v1/phone-numbers/{number['id']}",
headers={"Authorization": f"Bearer {os.environ['THUNDERPHONE_API_KEY']}"},
json={"inbound_agent_id": agent["id"]},
)
print("Your ThunderPhone number:", number["number"])
```
Your new number starts in `status="provisioning"` and transitions to
`active` within a few seconds; by the time you hang up your browser the
number is ready to take calls.
## Step 4 (optional): Set up a webhook
For real-time events (dynamic call routing, post-call processing) add
a webhook endpoint. Subscribe only to the events you need.
```bash
curl -X POST https://api.thunderphone.com/v1/developer/webhook-endpoints \
-H "Authorization: Bearer sk_live_YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"label": "Prod webhook",
"url": "https://your-server.com/thunderphone-webhook",
"events": ["telephony.incoming", "telephony.complete"]
}'
```
The response contains a one-shot `secret` — copy it to your secret
manager. Use that secret to verify the `X-ThunderPhone-Signature-V2`
header on incoming requests (see
[Webhooks overview](/webhooks/overview#signature-verification)).
## Step 5: Test your agent
Call the number you just provisioned. The agent picks up, introduces
itself, and follows your prompt.
Inspect the call after it ends:
```bash
curl https://api.thunderphone.com/v1/calls \
-H "Authorization: Bearer sk_live_YOUR_API_KEY"
```
Drill into a specific call to fetch the transcript and recording URL:
```bash
curl https://api.thunderphone.com/v1/calls/{call_id}/transcript \
-H "Authorization: Bearer sk_live_YOUR_API_KEY"
curl https://api.thunderphone.com/v1/calls/{call_id}/audio \
-H "Authorization: Bearer sk_live_YOUR_API_KEY"
```
---
## Next steps
Let your agent call your APIs during a conversation.
Trigger calls from your own code.
React to call events in real time.
Every public endpoint, documented.