I like simple solutions to problems, and I came across an easy way to extend a private portal and other collaboration tools to colleagues who are outside of your network. Since it’s available as a service, there is no investment to make in additional infrastructure or IT resources. With no up front costs and almost no development time, the solution is right for project teams that involve numerous outside contributors such as vendors, partners or consultants.

source:

https://www.networkworld.com/article/2304957/infrastructure-management/hyperoffice-extends-collaboration-to-your-outside-colleagues.html