curl --request POST \ --url https://api.vapi.ai/phone-number/buy \ --header 'Authorization: Bearer YOUR_ACCESS_TOKEN' \ --header 'Content-Type: application/json' \ --data '{ "areaCode": "YOUR_DESIRED_AREA_CODE", "name": "YOUR_PHONE_NAME", "assistantId": "YOUR_ASSISTANT_ID", "serverUrl": "YOUR_SERVER_URL" }'