Retrieve detailed information about a specific phone number configuration

{
  "_id": "<string>",
  "provider": "sip",
  "phone_number": "<string>",
  "friendly_name": "<string>",
  "sip_termination_uri": "<string>",
  "sip_trunk_username": "<string>",
  "sip_trunk_password": "<string>",
  "inbound_agent_id": "<string>",
  "outbound_agent_id": "<string>",
  "sip_infra_region": "global"
}