Provide a method of determining available UC extension numbersThe UC system can do an immediate check for a duplicate email address. while determining an available extension number is akin to searching for a needle in a haystack.Business Case:When creating a new user, we have no instantaneous\easy way to determine available extension numbers. This is further complicated in a multi-tenant/federated environment, where extension numbers cannot be duplicated.Proposed Solution:The creation of a dial-plan that limits each tenant to a unique range of extensions would solve the multi-tenant/federated issue. The business rules would limit these tenant-specific extensions range to not allow duplicates between the tenants.With the above dial-plan established, the new user creation screen would then show the next available extension number for that specific tenant.For bulk user creation: There needs to first be a report that runs against the above dial-plan to show available extension numbers (not exporting the existing users, to then determine which numbers are available) The import spreadsheet could then be populated with the available extension numbers.Alternately, the Bulk User process could prompt for how many extensions are going to be created, and grab that quantity of available extensions to include in the spreadsheet download.