For many implementations the system is flexible enough to provide pseudo "Multi Tenant Working". However the following caveats apply:-
The system supports one dial plan, all extensions can call each other and there can be no duplicate extension numbers. Outside callers have the ability to dial all extensions from the Auto-Attendant. A workaround here is to disable extension dialing in each Auto-Attendant and set up single digit dialing to the extensions within the tenant. Obviously this will only work with a small per tenant extension count.
Administration is system wide in the Portal.
The company directory is system wide. Extensions can be removed from the company directory and a simple recorded list could be provided.
With the addition of the Personal Operator feature you are able to have a unique operator for each user. When a caller reaches your personal greeting and dials zero for assistance the call is transferred to any destination assigned specifically to that user. Ultimately you cannot build completely separate tenants and have all StarBox features without using individual StarBoxes for each tenant.