curl --request GET \
  --url https://api.getoutbox.ai/settings/phone \
  --header 'Authorization: <api-key>'

{
  "results": [
    {
      "id": "<string>",
      "country": "<string>",
      "friendly_name": "<string>",
      "phone_number": "<string>",
      "agent": {
        "id": "<string>",
        "name": "<string>"
      },
      "rebill_on": true,
      "inbound_cost": 123,
      "outbound_cost": 123,
      "charge_per_second": true,
      "sip_uri": "<string>",
      "sip_username": "<string>",
      "sip_password": "<string>"
    }
  ],
  "integration": true
}