curl --request GET \
  --url https://api.open.cx/phone/sip/agents/{phone_agent_id}/config

{
  "inbound_numbers": [
    {
      "id": "<string>",
      "phone_number": "<string>",
      "status": "<string>"
    }
  ],
  "outbound_trunk_id": "<string>",
  "outbound_trunk_name": "<string>"
}