curl --request GET \
  --url https://api.threetone.in/v1/phone-numbers/inventory

{
  "countries": [
    {
      "country_code": "<string>",
      "country_name": "<string>",
      "provider": "<string>",
      "number_types": [
        {
          "number_type": "<string>",
          "setup_fee": 123,
          "monthly_fee": 123,
          "currency": "<string>",
          "available": true
        }
      ],
      "flag_emoji": "<string>"
    }
  ],
  "currency": "INR",
  "markup_percentage": 20
}