curl -L -X GET 'https://flux.postacksolutions.com/api/contacts' \
  -H 'Authorization: Bearer YOUR_ACCESS_TOKEN'

{
  "contacts": [
    {
      "userId": "6EAJHS27:user_456",
      "username": "jane_doe",
      "externalUserId": "user_456",
      "phoneNumber": "+1234567891",
      "createdAt": "2024-01-15T10:30:00Z"
    }
  ]
}