curl --request GET \
  --url https://api.open.cx/contacts \
  --header 'Authorization: Bearer <token>'

{
  "items": [
    {
      "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
      "email": "jsmith@example.com",
      "phone_number": "<string>",
      "name": "<string>",
      "custom_data": {}
    }
  ],
  "next": "<string>"
}