Re: Definition of UC depends on your role
The big challenge for allowing a mobile end user to exploit the flexibility of UC for all interactions (business apps, communication apps) from a single multimodal device, is to have all those apps being able to interoperate and integrate with shared user data quickly and easily. That's not so doable when those apps are in premise-based silos and using the PSTN for connectivity. By putting them into hosted/managed service "clouds" they are more easily accessible through IP connectivity and can also benefit from having unlimited amounts of storage.
So, basically UCaaS realy needs to be cloud-based service to provide all that flexibility to individual end users and their mutlimodal (but "dumb") endpoints, rather than be limited by job-related, premise-based hardware and software. When it comes to security, that is really a function for individual applications to control, in terms of authenticated identity access, user's rights, and using encryption-protected network connections.
The application "smarts" and access controls to information should be centralized in the service provider servers, not the access endpoints or networks. That's my perspective for the future of personalized services for individual end users who will be interacting with all kinds of business processes and people, either as a contact initiator or a recipient, through IP connected "cloud" services.
IBM's recent partnership announcement with Apple in developing "mobile apps" for enterprise oganizations is clear confirmation that this is the future for mobile consumers and employees.