“"Hi Brian, that should work provided you have the Skype for Business client installed on the mobile phone, and you have a data connection. You can download the app from the respective app store. If you've done that and calls still do not arrive, probably best to contact O365 business support. Information on that is at
We recently announced the ability for co-editors to chat with one another directly in a OneDrive document when working in Office Online. Today, we’re pleased to extend this capability to Office 365 Business and Education customers for documents stored in OneDrive for Business or SharePoint Online. Built on the same technology as Skype for Business, the new chat feature is available in all Office Online applications—Word, PowerPoint, Excel and OneNote.