Hello Alex,
Hubgets users own resources (extensions and data produced by extensions), have a role and belong to an Organization.
A Hubgets user can have multiple extensions. A phone extension is automatically assigned to every Hubgets user. That phone extension is displayed in the user's profile and can be called by other members of the organization. The same extension can be registered on more than one device (desktop browser, softphone app, IP Phone) and it will be reachable on all those devices.