Having this would be wonderful. Ideally, in advanced callflows, you should just be able to add/chain something on to the bottom of a pivot, like any other normal callflow element. Right now, this has to be done via the API or direct in the docs.
AFAIK, only way to do this is to use /v2/accounts/{account_id}/phone_numbers
If you set account_id to your root re-seller account, it will return all numbers for subaccounts also and you can loop through them/page through. You can also apply filters, such as "?filter_state=in_service or ?created_from=63627345744
in_service should mean that it's assigned to a callflow. avaialble should mean that it is not assigned to a callflow. You can look at the assigned_to field to see if it's assigned to a subaccount/an account other than your root re-seller account.
I take it https://github.com/2600hz/monster-ui-csv-onboarding is currently incomplete? Couldn't load the app via crossbar_maintenance or manually via the DBs.
Importing users and extensions via CSV will really save us on setup time