Does Zoom Room Outlook Calender Integration need external EWS?

[ChristianLauer]

Hi,

due to security concerns we discussing deactivating our Outlook EWS for external. We use Zoom Rooms with Outlook Calendar integration. So the question is, does Zoom Room need external EWS? And is it possible to name a source IP so that we can build network rules to protect the EWS? 

Thanks and regards

Chris