curl --request POST \
  --url https://api.getoutbox.ai/agency/phone \
  --header 'Content-Type: application/json' \
  --data '
{
  "friendly_name": "<string>",
  "phone_number": "<string>",
  "phone_number_id": "<string>",
  "inbound_cost": 0,
  "outbound_cost": 0,
  "charge_per_second": false,
  "rebill_on": false,
  "sip_uri": "<string>",
  "sip_username": "<string>",
  "sip_password": "<string>"
}
'