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

[
  {
    "id": "<string>",
    "integration": "twilio",
    "type": "phone_number",
    "country": "<string>",
    "friendly_name": "<string>",
    "phone_number": "<string>",
    "company": {
      "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>"
  }
]